Classic Rotary Phones Forum

Telephone Identification, Repair & Restoration => Telephone Restoration Projects and Techniques => Dial Repair & Lubrication => Topic started by: RDub on October 28, 2016, 04:47:58 PM

Title: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: RDub on October 28, 2016, 04:47:58 PM
Is there a scientific way to calibrate the pulse timing on a dialer or is it an experienced eye type of thing? And does timing, only, become an issue if you disassemble the gearing while cleaning / lubing during the life of the dialer? RDub
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Ktownphoneco on October 28, 2016, 05:18:15 PM
Good question.    I repair and restore telephone dials.   There are a number of scenarios floating around the antique telephone world that would lead one to believe that any number of methods can be used to determine if a dial is functioning correctly or not.     The only way to accurately test a dial to see if it's performing within the require parameters, is with some sort of dial test equipment.
I use a Sage Instruments 930-A telecommunications test instrument.      It gives me precise and accurate measurements of how a dial is performing, whether it's a pulse dial or a touch tone dial.
As I previously mentioned, a pulse dial has 2 parameters it needs to satisfy, speed and the break / make ratio.     The only way to do that in any sort of precise manner, is with an instrument designed for that purpose.   But the bottom line is, that if your telephone is dialing numbers accurately, and that is to say, if every time you dial a number, you reach the person or party you were trying to contact, then there's nothing wrong with the dial.     If that's in fact the case, leave it alone.   It's working correctly.

Jeff
 
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on October 28, 2016, 05:45:33 PM
There have been some two dozen topic on the forum which discuss the use of Audacity, a free download audio software package, to check dial speed and the break/make ratio.

This is one of my posts showing a really dirty dial's performance and the improvement after ultrasonic cleaning and oiling.

http://www.classicrotaryphones.com/forum/index.php?topic=11721.msg156265#msg156265

It's so easy to use and all you need are one shorter male/male phone plug cable, two alligator clip wire connectors and the dial (in or out of the phone).

Just put one 1/8" plug into the microphone input jack (have to use the more sensitive microphone audio input, the line in will not work) of a computer, connect the tip and one of the rings to the pulse contact terminals on the dial, if removed. If still in the phone with the phone closed, just attach the alligator clips to L1 and L2 (red and green line cord wires). Start the software, select microphone, start recording, turn the dial to zero, with a second or so and release the dial. Stop recording

(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=11721.0;attach=130176;image)

and record the time of the first break and the 9th make. That would be for 9 pulses. Divide 9 by the total time recorded to get PPS. 9 pulses divided by .9 seconds is 10 PPS.

You can then measure the time for each break and make section of the 9 pulses and divide those my the total seconds of one pulse cycle to get the break/make ratio, which should be around 60%/40%.

Based on what you find out for the dial, you can then take appropriate action, if any is needed.

There are also other testers out these to get the same information. Not having one, my computer with Audacity works just fine.

Search the forum for Audacity and read those related to dial speed testing.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Ktownphoneco on October 28, 2016, 07:30:57 PM
John   ...   If that works for you, and your happy with that arrangement, by all means, keep using it.     I just have some issues with that method.    First of all, and correct me if I'm wrong, what you've described is actually placing a direct short across the microphone input circuit of either a sound card, or an on board sound circuit built into the motherboard (MB).    I'm no computer expert, but I rather doubt that sound cards, add-on or built into the motherboard, were designed to accept a direct short.    Microphones are made in such a fashion as to provide a specific impedance, which in most cases, is acceptable to the input audio circuit of the card or MB.   The pulse springs of a pulse dial make a direct electrical contact with each other.      Albeit not a lot, but there's still voltage and current involved.    I'd prefer to play it safe and not cause damage to my sound card or MB by making it do something that it was never designed to do.    I went to the Audacity web site, and it doesn't explain how the software can be used to test telephone dials.    Most instruments designed to test and calibrate telephone dials, were obviously made for the purpose.    The machines or instruments that do that, are also calibrated at the factory to do that job.    Who calibrates the sound card and Audacity software in a computer to take accurate measurements of the pulses being produced by a telephone dial ?
I sometimes get 8 to 12 dials at a time, from flea market sellers who want dials cleaned, lubricated and checked for correct operation before they sell the telephones.   Some worn dials can take 5 or 6 speed adjustments to get a consistent dial speed.    My dials are fastened into a jig, that allows me to turn the dial towards me to dial numbers, then turned 180 degrees to make the adjustments on the back, all the while still connected to my test circuit, which is made up of 302 components, minus the ringer, mounted on a test board.
It all works very well for me, and I know once a dial is calibrated, it's operating perfectly.

But if anyone prefers to use their computer, Audacity software, and wire a pair of pulse springs to the microphone input jack, that's fine with me.    I just have no desire to place what amounts to a telegraph key across the mic input jack on my computer and start tapping out a message.

I trust no one will mind if I keep using my Sage 930-A to calibrate dials.

Jeff

 
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 29, 2016, 04:56:10 AM
I do it the same way as john, and it is important to not add any other voltages to the microphone than what the pc delivers on the microphone jack. (exception may be a tone generator, it should not deliver a signal strength large enough to ruin the sound card.)

To be completely sure, a $5 usb soundcard will be an insurance for not ruin the pc sound card.  I use the pc microphone input, and has done this for years. 

This way to do it helped me also to identify my one dial with one longer pulse, witch I did not know ever had been made.

Do you actually need to calibrate?  Well, its wort trying if your dial does not dial out on your line.
Speed is essential, make break ratio will normaly not change during the years, and the "exchange" tolerates pretty much. eg foreign dials with other ratios.

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: twocvbloke on October 29, 2016, 08:49:00 AM
Quote from: Ktownphoneco on October 28, 2016, 07:30:57 PMFirst of all, and correct me if I'm wrong, what you've described is actually placing a direct short across the microphone input circuit of either a sound card, or an on board sound circuit built into the motherboard (MB).    I'm no computer expert, but I rather doubt that sound cards, add-on or built into the motherboard, were designed to accept a direct short.

Having been a computer repair tech for a number of years, I've yet to come across a blown microphone input that is the result of a shorted out connection, soundcards for the past 20-odd years have come with protection on inputs to prevent damage to their circuits, and of course, the pulsing is for at the most 1 second, and for the occasional dial test every other month or so, it's not doing any damage to our computers. When I first had the idea to do it, I was worried about causing damage too, but, it didn't, and repeated tests didn't cause damage either, so the conclusion is, it works and isn't going to kill a computer...

In fact, the only sound card damages & faults I ever had to deal with was from people physically damaging the sockets on their sound cards or motherboards (usually tripping over wires and snapping sockets off the board, or ramming a computer so far back into a desk's cubby hole that the plugs were crushed and snapped off in the socket)...

It's great that you have a professional tool to do the job, but as hobbyists, we can't justify spending money on such equipment, so, we devise other contemporary means to analyse dial speeds, and this one works nicely. If you study the screenshots above, you'll note sections where the waveform seems to fall off in a tapered manner, that's the protection doing its job, when a short is detected it shunts the power to a capacitor and then to ground, and in the process audacity records the make/break "clicks" and hey presto, we get a nice reading to look at and determine if a dial is within spec or not, all for the cost of a couple of wires and a free piece of software. Again this is a contemporary solution to repairing dials, it's not up to spec with the official repair houses that are long gone, granted, but, it is a hobbyist-level fix... :)

Though I do see that recommending a professional level tool to do a couple of tests here and there is like an electronics engineer saying you need a $2k oscilloscope to do a continuity check on a simple DIY circuit that has a broken connection, yeah, it works, but, it's an expensive solution to something that has far simpler hobbyist-level means to achieve the same result, such as a couple of wires, an LED and a battery to make a continuity tester, saving a cost of $1999.50 (if that!), it goes back to the old World War II slogan, "Make do and Mend"... :)

Oh, and Audacity is used for a lot of things that they don't mention on their website, they just provide the tool for the job, to record audio signals, the end user provides the functions, operations and inputs... :)
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 29, 2016, 09:17:05 AM
Jeff:
If I had a Sage 930-A to calibrate dials, I would have used it, but it will cost me pretty much to get one.  But just shipping and customs will be approx $200 to Norway, I feel I could spend that better.
I would end up with one in used condition to 2-300!

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Ktownphoneco on October 29, 2016, 10:12:44 AM
As I understand it, the microphone circuit associated with a sound card, or the onboard sound circuitry, is designed to produce somewhere around 10mV to power the microphone inserted into the jack.    I suppose that isn't a lot of voltage to short out, but I would imagine it's important to remove the male jack as soon as the dial test is completed, rather than leaving it plugged into the mic jack while the graph is analyzed.    However without comparing the results of the same dial connected to an actual dial testing instrument, how do you establish that the results obtained through a PC, using the Audacity software are accurate ?     I can carve out a handle on a 2"x 4" piece of lumber, and use it as a baseball bat, but my accuracy when hitting the ball will be way out of whack.   As I see it, using a software program designed to analyze audio through a properly working microphone, isn't the same as asking it to measure the speed and duration of a series of short circuits.      If the results can't be gauged or compared against the results achieved through a proper piece of equipment designed and calibrated for the specific purpose of measuring the speed and break / make ratio of a pair of pulse springs, the accuracy of those readings can't be confirmed.
But if you feel it works, and your happy with the situation, then use it by all means.     But I'm still not convinced.

However, out of curiosity, I'll do this when I have a few minutes to spare.

I have an old computer in my shop that has either a sound card, or sound circuit built into the motherboard, ( I just can't remember which ), and I really don't care one way or the other, whether or not the test damages the sound circuit.

(1)  I'll download the Audacity software and install it on the old computer.
(2)  Make up a microphone jack with cord and alligator clips on the 2 conductors.
(3)  Select an "un-serviced" Western Electric dial in good shape, and which appears to be operating well.
(4)  Test it on the Sage 930-A, and record the results.
(5)  Then connect the same dial to my old computer, and record the results obtained using the PC and the Audacity software.
(6)  Then post the results of the comparison tests conducted using both methods.

Who knows, maybe I'll only manage to shoot myself in the foot.

By the way, Sage telecommunications test sets get obsolete fairly fast, and they can be purchased off eBay fairly cheap.    I bought mine for $95.00 plus shipping.    The thing one needs to know is if the 930-A set has the add-on card for the tests that the purchaser wants to perform.     Pulse speeds and break / make testing and DTMF frequency tests with the 930-A requires "Option Card - 01".    There are approximately 31 Option Cards for this unit.     The instrument itself, operates on either 48Volts DC, or 115 or 240 Volts AC, but not both.

Results to follow when I have time to do the comparison tests.

Jeff





Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 29, 2016, 10:38:13 AM
The microphone input on PC sound cards is highly current limited, so I don't see any reason for concern in shorting it with a dial.  The small voltage that is present on the input is only there to power the field effect transistor that is present in most electret microphones to reduce the very high impedance of the microphone to the few kiloohms of the sound card input.

Audacity has nice application features for measuring timing, which are really native to its intended use as a sampling application.  In addition, sound card sampling rates are very high with modern PCs to generate better than CD quality recordings. I think Audacity has been used for many such measuring tasks, and there is no reason to expect that application to be explicitly outlined in the manual.

I would venture to say that the sampling of a PC sound card is far superior to what a Sage 930 does. Of course, such high accuracy is not even needed.

The manual way of recording the sound with the application and analyzing the trace is quite time consuming, I would say, not something I would want to do for routine work when adjusting dials, which may take a half dozen or more tweaks and measurements.  This may be ok if you do your ONE dial, and may be fun to do once a while as a hobby, but if you want to help others and tune their dials, something more expedient is needed. There is more to life as a collector than tuning dials.  Sage 930 units are dirt cheap these days, I got mine for $20 and again ca. $20 for shipping. It is easy to quickly run through all digits on the dial and display rate and break/make ratios.

I have also used an Ameritec AM7 Central Office Simulator, which writes a timing analysis to the serial port after dialing for both pulse and touch tone, and a complete frequency analysis for TT.
Mine has 20 FXS ports for use a programmable intercom, much like a little PBX, such as the Panasonic types.

I have also built my own dial measuring device, based on an Arduino chip and board for less then $5, but the rest of the cost is in writing the program to do the job.


PS: I see that Jeff posted in the meantime. Only thing I have to say is that the accuracy of a Sage for measuring dial speed is in no way superior in terms of accuracy to recording the sound trace. I don't understand the doubt of accuracy of the sound method, it is by nature of much higher accuracy even on slow, old PCs.

PS: CORRECTION:  I got my 930A for $9.99 plus $14 for shipping.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 29, 2016, 11:26:36 AM
Quote from: Ktownphoneco on October 29, 2016, 10:12:44 AM
As I understand it, the microphone circuit associated with a sound card, or the onboard sound circuitry, is designed to produce somewhere around 10mV to power the microphone inserted into the jack.    I suppose that isn't a lot of voltage to short out, but I would imagine it's important to remove the male jack as soon as the dial test is completed, rather than leaving it plugged into the mic jack while the graph is analyzed.    However without comparing the results of the same dial connected to an actual dial testing instrument, how do you establish that the results obtained through a PC, using the Audacity software are accurate ?     I can carve out a handle on a 2"x 4" piece of lumber, and use it as a baseball bat, but my accuracy when hitting the ball will be way out of whack.   As I see it, using a software program designed to analyze audio through a properly working microphone, isn't the same as asking it to measure the speed and duration of a series of short circuits.      If the results can't be gauged or compared against the results achieved through a proper piece of equipment designed and calibrated for the specific purpose of measuring the speed and break / make ratio of a pair of pulse springs, the accuracy of those readings can't be confirmed.
But if you feel it works, and your happy with the situation, then use it by all means.     But I'm still not convinced.

However, out of curiosity, I'll do this when I have a few minutes to spare.

I have an old computer in my shop that has either a sound card, or sound circuit built into the motherboard, ( I just can't remember which ), and I really don't care one way or the other, whether or not the test damages the sound circuit.

(1)  I'll download the Audacity software and install it on the old computer.
(2)  Make up a microphone jack with cord and alligator clips on the 2 conductors.
(3)  Select an "un-serviced" Western Electric dial in good shape, and which appears to be operating well.
(4)  Test it on the Sage 930-A, and record the results.
(5)  Then connect the same dial to my old computer, and record the results obtained using the PC and the Audacity software.
(6)  Then post the results of the comparison tests conducted using both methods.

Who knows, maybe I'll only manage to shoot myself in the foot.

By the way, Sage telecommunications test sets get obsolete fairly fast, and they can be purchased off eBay fairly cheap.    I bought mine for $95.00 plus shipping.    The thing one needs to know is if the 930-A set has the add-on card for the tests that the purchaser wants to perform.     Pulse speeds and break / make testing and DTMF frequency tests with the 930-A requires "Option Card - 01".    There are approximately 31 Option Cards for this unit.     The instrument itself, operates on either 48Volts DC, or 115 or 240 Volts AC, but not both.

Results to follow when I have time to do the comparison tests.

Jeff
I guess you have one point here who can make this inaccurate, and that is the human reading of the data. 
I have often done the measurements just connecting the telephone directly to the mic jack without using time to disconnect the dial, and even that makes a good reading for me. 

When you use an analyzer you will probably get the same reading at least 8 of 10 times testing in series. 
If you please just make recording, e.g. as an MP3 or WMA file and put out a link here or email it or store it on sound-cloud etc we could try to analyze it on different computers and see how much our readings vary.  One recording of a zero with at least 1/2 second of silence in each end will do.  This could interesting! since you have the tester we could compare at the end.

(My interface is a 3.6 mm mono plug connected to an old-fashioned telephone jack)

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 29, 2016, 11:55:47 AM
You may try on these two, I have not analyzed them yet.

https://soundcloud.com/d_s_k-2/ericofon

https://soundcloud.com/d_s_k-2/starlite

dsk

Edit: forgot the links.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Dan/Panther on October 29, 2016, 01:48:04 PM
I dial the wheel all the way to '0', then release, and count 1001. It should make the entire travel in that time frame. One second or so. I find that is almost universally the case, with a clean dial. I think they are somewhat forgiving.
D/P
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 29, 2016, 03:05:30 PM
That well be good enough for the most. Only some equipment will need a more accurate tuning.
dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on October 29, 2016, 03:13:08 PM
Here are two wave sound files (attached) in case anyone wants to analyze them. All I will say is that one tested slow and the other fast.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 29, 2016, 03:28:13 PM
Both ways of transferring the files works, Ill send you my results as a PM, and you may make it offical when you feel you have the right feedback.

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: DoubleTone on October 29, 2016, 07:29:28 PM
Another alternative: a TPM32 Digit Grabber, available on eBay (as in, right now) for about $60+.  I bought one several years ago, and for dial calibration, it's excellent.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: ..... on October 29, 2016, 08:59:50 PM
Quote from: DoubleTone on October 29, 2016, 07:29:28 PM
Another alternative: a TPM32 Digit Grabber, available on eBay (as in, right now) for about $60+.  I bought one several years ago, and for dial calibration, it's excellent.

Here's one starting at $10.00

http://www.ebay.com/itm/Metro-Tel-TPM32-Touch-Tone-Digit-Grabber-/302118208864?hash=item4657a60560:g:A90AAOSwnbZYD5w9
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 30, 2016, 01:26:55 AM
Quote from: DoubleTone on October 29, 2016, 07:29:28 PM
Another alternative: a TPM32 Digit Grabber, available on eBay (as in, right now) for about $60+.  I bought one several years ago, and for dial calibration, it's excellent.

This thread has lots of arguments for and against this or that, and we will probably not even agree about the need of accuracy, but does this unit tell how fast or slow the rotary dial are, or the make/brake ratio?

The need of accuracy are not pretty high on my equipment, so I will not tune the 2 dials I posted sound files of, but if I have to tune it I will try to tune it as good as possible brake at 60-66% and speed 10-12 pps will be OK

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: DoubleTone on October 30, 2016, 03:24:21 AM
Quote[...] does this unit tell how fast or slow the rotary dial are, or the make/brake ratio?

Yes, and yes.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Stan S on October 30, 2016, 08:11:18 AM
"Yes, and yes."

The answer is no and no.
They made different models all having the same number. That one is Touch Tone only.

It's my auction.
You have to be careful with those.
Stan S.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on October 30, 2016, 08:44:36 AM
Quote from: dsk on October 30, 2016, 01:26:55 AM
[ ... ], but does this unit tell how fast or slow the rotary dial are, or the make/brake ratio?

. . . and other than a digital oscilloscope that can capture and display a trace, does or do these "averaging" analyzers tell a dial's full story like this, first the as found state or condition of a dial

(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=11721.0;attach=129957;image)

and the state or condition of the dial after cleaning and oiling?

(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=11721.0;attach=130176;image)

Yes, it take a lot longer to hook up the dial after the computer is turned on, the capture the audio file, to determine each event point in time (start-stop and each break/make point) and to put that data into an excel template to analyze the dial, then to do a screen capture of the audio file, past it into Photoshop and annotate the dial analysis for personal use or posting. That would be about 30 minutes work once comfortable doing all that (having done it enough in the past to make it easy).

Certainly not something a high volume refurb person or shop would want to do but in my opinion, very useful to a hobbyist who not only wants to fix/restore a dial but also understand what is wrong with it and see the effects of their work. There's at least 4 unique issues seen in the first image above.

Just saying, a lot of time to get these scans but IMHO, invaluable for the hobbyist trying to understand a dial and fix/restore it by taking a scan after each procedure performed (the difference is the dial between being cleaned and then being oiled and then several days later to see if the oiling has kept the dial the same (I just discovered the oil I used does not hold up over time (months) and as such am in the process of switching to a different, more expensive oil).

Just saying, but I do appreciate all of the information I can capture at different points in time and retain it digitally on any dial in my possession.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 09:29:52 AM
Quote from: TelePlay on October 30, 2016, 08:44:36 AM
. . . and other than a digital oscilloscope that can capture and display a trace, does or do these "averaging" analyzers tell a dial's full story like this, first the as found state or condition of a dial



and the state or condition of the dial after cleaning and oiling?



Yes, it take a lot longer to hook up the dial after the computer is turned on, the capture the audio file, to determine each event point in time (start-stop and each break/make point) and to put that data into an excel template to analyze the dial, then to do a screen capture of the audio file, past it into Photoshop and annotate the dial analysis for personal use or posting. That would be about 30 minutes work once comfortable doing all that (having done it enough in the past to make it easy).

Certainly not something a high volume refurb person or shop would want to do but in my opinion, very useful to a hobbyist who not only wants to fix/restore a dial but also understand what is wrong with it and see the effects of their work. There's at least 4 unique issues seen in the first image above.

Just saying, a lot of time to get these scans but IMHO, invaluable for the hobbyist trying to understand a dial and fix/restore it by taking a scan after each procedure performed (the difference is the dial between being cleaned and then being oiled and then several days later to see if the oiling has kept the dial the same (I just discovered the oil I used does not hold up over time (months) and as such am in the process of switching to a different, more expensive oil).

Just saying, but I do appreciate all of the information I can capture at different points in time and retain it digitally on any dial in my possession.


You should be able to shorten the analysis time considerably, by using the built-in tools in Audacity to give an almost immediate read-out of the dial speed.
Audacity can analyze data in time and frequency domains.  By using an autocorrelation function on the trace it should tell you immediate the duration or frequency of the beats in the sample. With some research a plug-in could be written for Audacity that would optimize the settings for dial speed data and provide an immediate read-out of at least dial speed.  But it should also be possible to automatically analyze the break/make ratio.  This would be really no different than what I am doing in my home-built analyzer with an Arduino, only it is analyzing the data in real-time, rather than taking the sample from a file.
My analyzer samples the on-off status of the switch with sufficient resolution and computes the average make and break duration for a full digit. This is exactly the same principle that you are doing manually. The real-time analyzer is just complicated a little by the fact that it has to automatically detect the beginning of a digit, and distinguish that from a on-hook and off-hook condition, and from hook switch flash signals.

If you still have the sound file of this plot, try the following:

a) Plot the frequency spectrum
b) try some of the auto-correlation options in the Algorithm tab:  Try Standard and Enhanced.
It should give you peaks for the frequencies of the sample.

I don't know whether this provides sufficient accuracy, or entails more guess work, as you will have to select the true fundamental frequency from a spectrum, but it should be in the 8 to 12 Hz range.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 10:10:03 AM
ok, I just tried the autocorrelation myself on the two files that you provided earlier.

I come up with the impression that the first of files has a lot of jitter in it, and I think it will test mostly fast at around 12 to 12.5 pps, but does have some low frequency components between 7.9 and 8.3 pps.

The second file (AE Dial 02) seems to perform more uniformly, but slow at 7.8 pps.

What does your manual measurement determine?  I have to admit that I am too lazy to do that myself.

It may be that the first dial does not have a constant recoil speed, perhaps it is slowing down during the return rotation.


AE Dial 01 Speed Audio File.wav
AE Dial 02 Speed Audio File.wav
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on October 30, 2016, 10:29:07 AM
Wow, first, I didn't know Audacity had all of those features. I downloaded it years ago for use making and editing sound effects on my PC when at the theater during rehearsals (I use Adobe Audition on my home main PC to do most of the heavy lifting work of sound design but needed an easy to use audio program when on the road for last minute creations/adjustments). I'll have to look into those features so thanks for the lead/tip.

As for the two files, both are as found condition. One is indeed 12.13 PPS and the other 7.80 PPS. I have the manual analysis image files on my other computer and will add them to this post later today. dsk also got the same numbers so exchanging data files for analysis on other computers to test this method seems to confirm no variation due to systems/software used.

As a side FYI, seems anything can be attached to a forum post by enclosing it in a .zip file. Audio files (wav, mp3, etc) are not allowed and can not be uploaded unless encased in a .zip folder. Good to know for anyone wanting to post an audio file.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 10:44:36 AM
Ok, the candidate gets 100 points, LOL.  I call that an unqualified success, as far as dial speed is concerned.
While you posted I cropped the screenshots I took earlier.

After loading your files, I cropped them to the data just before and after the signals.  On that I applied a 100 Hz low pass filter to get rid of all the features that not pertinent to our interest here.  Those are shown in the top portion of these screenshots.

The lower portions show the enhanced autocorrelation functions of each trace.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 30, 2016, 11:59:53 AM
I love this kind of threads, and will like to underline a few of my ideas.

Do not try to repair somethings working. Regular cleaning and oiling and service may still be done if you consider it is smart to do it.
Audacity and sound files together with a good spreadsheet is good enough for the hobbyist to tune a dial or two from time to time. The make break ratio will usually not change considerably during regular use, and most equipment will read a zero of a dial using approximately the time it takes to say 1001 from release to stop.  (Siemens dials slightly longer, they have long way to move between 1 and stop)  A rough but good enough for me, spreadsheet is here: https://docs.google.com/spreadsheets/d/1iUKj3jlKp7EoqXAOceQozimP6Pb4OKyP9l5B_KFUztg/edit?usp=sharing (https://docs.google.com/spreadsheets/d/1iUKj3jlKp7EoqXAOceQozimP6Pb4OKyP9l5B_KFUztg/edit?usp=sharing)

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 12:20:32 PM
The manual method that you used to analyze your dial 'sound' trace is the simplest form of time domain analysis. You measured the time between transitions between on- and off-states at the zero crossings, and reduced the data for 10 pulses by averaging to yield just one number.

Autocorrelation is a mathematical technique used in digital signal processing (DSP), that is more sophisticated, and relates to frequency domain analysis by the Fourier method, although it is still a time-domain technique.

I am certain this is also the technique used in the Sage Instruments 930A. It uses DSP algorithms for many of its tasks when measuring frequency.  When you get some experience with that instrument you'll find that it rarely provides a definitive constant number for the dial speed. There is always some fluctuation. This stems from the nature of the signal, it contains noise and old dials do no rotate with a completely constant speed for every digit.   From my autocorrelation graphs you see that the peaks have a certain width, can even have fine structure internally with multiple smaller peaks.  Now the question arises which one do we pick as the dial speed ?  I don't know what the Sage does exactly, but I suspects it computes some statistic on those peaks, perhaps fits a curve to it, and takes some kind of average after satisfying a set of signal thresholds. The results can vary from time to time, and they do.  I have had some dials that even seemed to completely confuse the box, and it was frustrating for this user too. Perhaps an example might be your dial that is mostly fast and partly slow.  In these cases, your method of recording these traces and using a spectrum analyzer should explain the situation better, and actually it did!

One more aspect: The trouble with simple autocorrelation has always been that the result is not immune to the harmonics of the true or expected main frequency.  Peaks show up not only at their "nominal" frequency, but at twice or other multiples of it.  This is avoided by many enhanced autocorrelation techniques that mathematicians have developed, some of which are also implemented in Audacity, hence my recommendation to try those.  I do have some additional screen shots that I took earlier to select those that I presented.  Later...

[PS: for early readers, I misstated the relationship of time and frequency domain in my first draft of this.]
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Contempra on October 30, 2016, 01:21:39 PM
Quote from: dsk on October 30, 2016, 11:59:53 AM
I love this kind of threads, and will like to underline a few of my ideas.

Do not try to repair somethings working. Regular cleaning and oiling and service may still be done if you consider it is smart to do it.
Audacity and sound files together with a good spreadsheet is good enough for the hobbyist to tune a dial or two from time to time. The make break ratio will usually not change considerably during regular use, and most equipment will read a zero of a dial using approximately the time it takes to say 1001 from release to stop.  (Siemens dials slightly longer, they have long way to move between 1 and stop)  A rough but good enough for me, spreadsheet is here: https://docs.google.com/spreadsheets/d/1iUKj3jlKp7EoqXAOceQozimP6Pb4OKyP9l5B_KFUztg/edit?usp=sharing (https://docs.google.com/spreadsheets/d/1iUKj3jlKp7EoqXAOceQozimP6Pb4OKyP9l5B_KFUztg/edit?usp=sharing)

dsk

Hi dsk ,... First , I've never adjusted a dial on rotary phone , secondly , I don't understand the spread sheet . so what is the difference ? i can call every where without problems !, can you explain me ?.. oh I rebuilted some dials but no adjustment on them .
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 01:22:46 PM
Here are the  "Standard Autocorrelation" plot and the "Enhanced Autocorrelation" (per Audacity) of the first of John's dials.

By immediate visual inspection we see that the enhanced version is much cleaner.  On second view we also see that the low speed (= high lag) component is almost not visible in the simple version, it can easily be just overlooked.  It is obscured by the first "harmonic" with twice the time delay (0.160 s) than the first.

Our dominant time delay is at 0.080 s, which corresponds to 12.5 PPS, which may be identified in both plots, but it is very impressive how the second method enhances that data.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Dan/Panther on October 30, 2016, 02:01:27 PM
Personally I guess that the accuracy of the dial can be set to perfection if one chooses. However like I mentioned, of the scores of phones that I have cleaned and restored to functionality, every single one worked as it should. Maybe I just got lucky ?
D/P
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 30, 2016, 03:05:27 PM
I usually do not fix things who works, and to Dan, and Dennis. You will only need this in a few situations, to fix a physical damaged dial, or to cope with some analog adapters.  It is not about luck, but a sudden feeling of whats right, and the most of telephone equipment is made to tolerate really large differences. Usually it works without any hi-tech adjustments.

I actually finds this interesting, and it looked like my Starlite had a slightly different last pulse, an yes it had.  By visual inspection I could observe the last pulse was disturbed by the little finger securing the pulse contact in closed position when the dial is resting. Only tools need was a pair of pliers.   But as you have observed, this was not necessary to do, it worked before too!

What could I to make the audacity visualization better for this thread?  Adding a 1000Hz tone and feeding back to the microphone input.  Here follows my readings, the spreadsheet with values from audacity.  And then I read out pretty good readings of make and break ratio, and PPS value. 
Enclosed pictures.

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 30, 2016, 03:11:30 PM
As you see, the speed is a little slow 9.65 when I would like to have 10, by my opinion good enough.
The same about brake length I would prefer 60-66, but got 66.58.  No reason for adjustments. 

Should I sell it as adjusted, it would be a different case, It had to be within 60-66% and 10-12 PPS.

By theory, it is not good, in practice life, its more than good!

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on October 30, 2016, 06:35:18 PM
Quote from: unbeldi on October 30, 2016, 10:10:03 AM
ok, I just tried the autocorrelation myself on the two files that you provided earlier.

I come up with the impression that the first of files has a lot of jitter in it, and I think it will test mostly fast at around 12 to 12.5 pps, but does have some low frequency components between 7.9 and 8.3 pps.

The second file (AE Dial 02) seems to perform more uniformly, but slow at 7.8 pps.

What does your manual measurement determine?  I have to admit that I am too lazy to do that myself.

It may be that the first dial does not have a constant recoil speed, perhaps it is slowing down during the return rotation.


AE Dial 01 Speed Audio File.wav
AE Dial 02 Speed Audio File.wav

Got to the computer I use to do dial tests, where the analysis files are parked so they are attached as well as the spread sheet I use (in a zipped folder) to determine PPS and the break/make ratio for each digit, and then the average of those ratios (the long hand, time consuming way to do it)
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Contempra on October 30, 2016, 07:36:57 PM
Quote from: dsk on October 30, 2016, 03:11:30 PM
As you see, the speed is a little slow 9.65 when I would like to have 10, by my opinion good enough.
The same about brake length I would prefer 60-66, but got 66.58.  No reason for adjustments. 

Should I sell it as adjusted, it would be a different case, It had to be within 60-66% and 10-12 PPS.

dsk

Okay but how to adjust the dial ?  all i see is 2 screws !.. As i said , i've never adjusted a dial but all works ... but i'd like to know how to adjust a dial .. thanks
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 08:55:56 PM
You can also automate the measurement of the break ration, although I did not find a suitable filter in Audacity, although the function for the first step of that is available.
The principle is the same that most analog break/make measuring instruments used by Western Electric, for example in the No. 2B test sets for pulse train measurements.

The method involves clipping your sound recordings at the top and the bottom to a square wave with the zero line exactly in the middle. That means removing any DC bias from the signal.  Let's say you clip the data to values +1 and –1, centered on 0.  This can be done with the clipping function in Audacity. In addition the data should be clipped to a some number of complete dial pulses, not more and not less.  I am showing the result below for your No. 2 sample.

The next step is to divide all data into sample slots, which they are in already actually, because the data is sample at a certain frequency. I believe it was 44.1 kHz in your samples.  So, all you have to do now, is compute the sum of all samples, i.e. adding the sequence of –1 and +1 values.  Image that the make/break ratio is exactly 50%, this would mean that there are the same number of negative values as there are positive values and the sum would be zero.  For 66% there are 2x as many samples of one polarity vs the other. There the sum is a direct representation of the break/make ratio.  With the polarity in your data, negative being a break, the sum is positive below 50% and negative above 50%.  All you need to do is count the sample properly which is the 100% value and normalize the value.
This should be very simple to implement in an Audacity plug-in, the hardest part being learning how to do that.  I would actually be surprised this does exist already somewhere as a third party module. I will look.

I will attach the promised image in a moment...

The top graph shows the original data trimmed to 9 pulses, and the lower half shows the clipped data normalized to +1 and –1.

BTW, if one uses this clipped signal, the correlation function cleans up amazingly, and provides a nice bell curve for reading the principle frequency.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 09:10:30 PM
Quote from: unbeldi on October 30, 2016, 08:55:56 PM
BTW, if one uses this clipped signal, the correlation function cleans up amazingly, and provides a nice bell curve for reading the principle frequency.

Here is the graph for that.

There is now almost no uncertainty in reading the peak value, which has a delay of 0.1258 seconds.  Taking the inverse of that, gives  7.95 PPS.
You can't expect it to be exactly the same as before, but we have to remember that previously, I just took a guess at the peak.

Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on October 30, 2016, 10:01:54 PM
Ok, last post today, I promise.

Attached is a paper introducing a break/make ratio meter of 1933 by Ericsson in Great Britain.
I came across it not too long ago while researching other matters.

Ericsson Bulletin January 1933, No. 2, page 16  A new Impulse Ratio Tester
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on October 31, 2016, 02:02:46 AM
Quote from: Contempra on October 30, 2016, 07:36:57 PM
Okay but how to adjust the dial ?  all i see is 2 screws !.. As i said , i've never adjusted a dial but all works ... but i'd like to know how to adjust a dial .. thanks

This time, I  shall try to not mix threads, but take a look at this thread: http://www.classicrotaryphones.com/forum/index.php?topic=15443.0

Every dial has their slightly different way to adjust the tension on the centrifugal break, Typical dials used here looks like AE dials were you have to bend on the springs. but anyway we are talking about the same principles. 

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on November 01, 2016, 01:41:16 PM
I  would like to thank everybody who has contributed to this thread, it has made me making the process of using audacity better.
dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on November 04, 2016, 08:40:39 PM
As an FYI follow up, I have a very slow ASUS Notebook that I bought 5 years ago for a traveling reason but haven't used it for that in 3 years. Use it occasionally to keep it updated and battery charged.

It's now in my dungeon hooked up by hard wire to my internet box. Put a full sized external HP keyboard that someone at work tossed in the dumpster a year ago on it, added a wireless mouse, a large display I had on a now dead computer. Found a Creative external USB sound card I used many years and computers ago (to add 5.1 stereo to my laptop for theater work) and downloaded Audacity.

The external sound card being a nice buffer between a dial and Audacity. Just checked my first dial. Works great - no need to run upstairs to my desk top to check dials anymore.

So, all the junk I had laying around in this box and that box is now a very nice platform for dial checking, and everything else on the internet. I'm happy.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Pourme on November 04, 2016, 08:57:33 PM
Excellent, John. I had thought about doing the same thing, to avoid taking dials from my workspace to my office. I never kept any of my old computer equipment. I want to keep working on my phones restricted to my bench. Whatever I use to work on dials I will have to learn. After considering these reasons I ordered a 930a this week off of EBAY. I have a spot on my bench ready to place it. I have much to learn and all winter to learn it!
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on January 02, 2017, 02:08:33 AM
Had a 10A dial in a late 60s Trimline that was a bit slow when nearing the end of returning when dialing 0. The first image shows the break/make analysis for 10 digits. The slow down at the end is clearly apparent. Analysis of the data shows an overall PPS rate of a bit more than 9 and the break/make ratio near 60/40.

The bottom of the first image shows the break/make digital wave form for 10 digits after the dial was removed, stripped down to it's basic metal/plastic components and cleaned ultrasonically for 25 minutes, rinsed off with water and then distilled water, excess water blown off with compressed air and then heated to about 100-105 degree with a hair dryer for a few minutes. All of the bearing and friction points were oiled with a watch oil. On re-assembly, 1/3 of an extra turn was put into the dial spring. This bottom wave form shows no problem as the dial ends a 10 digit cycle and each pulse cycle looks cleaner that the as received wave form.

The bottom image is a side by side spread sheet analysis of the pulse data, before on the left and after on the right. The dial picked up 1.3 PPS from 9 to 10.3 PPS, some of that increase due to cleaning and oiling and a bit due to the extra tension put into the spring.

What's interesting is the standard deviation for break and make periods for each of 10 pulses before and after cleaning. While the average ratios before and after are acceptable and very similar (note - graph labels for the average break/make are reversed), the standard deviations improve from 1.441% to 0.619% for the measured "make" times and from 0.947% to 0.733% for the "make" times. That would indicate a more consistent break/make period over all 10 pulse periods.

This was done the hard way, data read off of Audacity wave form and manually entered into an Excel spread sheet.

Presented as further anecdotal evidence that dial ultrasonic cleaning works to clean without fill disassembly and Audacity with Excel is a good combination of software tools. While the "dirty" dial may have worked, the "cleaned" dial would produce better results when dialing.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on January 02, 2017, 02:38:12 AM
Quote from: TelePlay on January 02, 2017, 02:08:33 AM
...

The bottom image is a side by side spread sheet analysis of the pulse data, before on the left and after on the right. The dial picked up 1.3 PPS from 9 to 10.3 PPS, some of that increase due to cleaning and oiling and a bit due to the extra tension put into the spring.

What's interesting is the standard deviation for break and make periods for each of 10 pulses before and after cleaning. While the average ratios before and after are acceptable and very similar (note - graph labels for the average break/make are reversed), the standard deviations improve from 1.441% to 0.619% for the measured "make" times and from 0.947% to 0.733% for the "make" times. That would indicate a more consistent break/make period over all 10 pulse periods.

This was done the hard way, data read off of Audacity wave form and manually entered into an Excel spread sheet.

Presented as further anecdotal evidence that dial ultrasonic cleaning works to clean without fill disassembly and Audacity with Excel is a good combination of software tools. While the "dirty" dial may have worked, the "cleaned" dial would produce better results when dialing.


You did the right thing, all the way.
Adjusting the spring did solve the slow speed on last digit, and that did probably also make the make/brake correct for the last pulse too, if you look at the make/break on the 5 first digits of before and after, it is pretty constant (=right).

The make/break ratio has different standards here and there but all my exchanges, and dial gizmos has accepted them all.  The break is 2/3 in some countries, and 60% in others so if I should adjust a dial in hence of this, I would put it  between 60 and 67 %.

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on February 06, 2017, 02:52:27 PM
Recently it was several B&K Telephone testers at EBAY. But are they good enough to test phones for use on IP adapters?
The Norwegian standard for dial speed was to tune between 10 and 12 pps, witch probably tells us about the exchange should accept e.g. 8-15 pps?? We have brake/make 60/40 UK has 2/3 to 1/3 Never recognized problems with the ratios on regular phones so I just have to guess about it to be tolerant.

dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: Jim Stettler on February 06, 2017, 06:29:29 PM
I think the BK 1045's use the same dialing  tolerance as the phone company . If that is the case, then I don't think the tolerance is tight enough for IP.

Just a guess tho,
Jim S.

Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: unbeldi on February 06, 2017, 06:48:15 PM
Quote from: Jim S. on February 06, 2017, 06:29:29 PM
I think the BK 1045's use the same dialing  tolerance as the phone company . If that is the case, then I don't think the tolerance is tight enough for IP.

Just a guess tho,
Jim S.


The specification of the 1045B shown earlier speaks against the first of your statements.  Also my experience dispels that notion.
The specs state, in other words, that a break ration of 30% to 85% is accepted as long as the total dial pulse cycle lasts at least 100 ms, and that the dial speed can be 8 to 20 PPS.  The lower value of the PPS is perhaps not low enough for many old telephone dials, because I have seen many between 7 and 8 PPS, but I don't recall whether I had problems on my 1045A.

But, the same specs appear to contradict themselves, because if the unit accepts 20 PPS signaling, then the pulse cycle can only be 50 ms long, violating the "Recognition Time (end of digit)" of 100 ms minimum.  I am sorry, that is not correct. I misinterpreted that statement.  That specification is the time the unit needs to evaluated the preceding pulse sequence as a complete digit, not the pulse cycle time.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on February 07, 2017, 01:23:29 AM
Quote from: unbeldi on February 06, 2017, 06:48:15 PM

The specification of the 1045B shown earlier speaks against the first of your statements. 
You are right, and I do not know whats right, telephones collecting is not a religion, it is lots of science, but also experience of whats good enough or not.
I have 2 reasons for adjusting my own telephone dials:
1) Learning by doing.
2) Reapair it if it is not working well enough.

When I first have to do something I want it to be so accurate as reasonable. That gives a speed of 11 +/- 1 pps.
The make break ratio is something i usually do not need to adjust at all, but again if I have to I will get as close to 60% percent break as I can without risk of breaking anything, but I am satisfied up to 67% (UK std) since it never has made problems for me. I even have an old 1920ies dial never adjusted and it works at 50% No need for adjusting as long as my electromagnetical PAX understands it , so do the Dialgizmo and the Mitel smart 1. 
What I know is 15 pps is to fast for my PAX.
I have read here on the forum about problems using rotary phones on some ATA's, and I have an Ericsson exchange not accepted by the  Dialgizmo, but by the POTS line. (I should have used more time to figure out why)

I am so happy with this forum, because I can learn something day by day, and discuss such problems here.   ;)
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on March 06, 2017, 08:49:05 PM
Just discovered another use for Audacity. I have a Kellogg stick transmitter and wanted to test it for working condition. I attached the two alligator clips normally placed on the dial pulse contacts on the transmitter terminals, started to record in Audacity and was able to record my voice and listen to the quality of the sound on playback.

Not a precise measurement but if one were to use a constant volume sound source placed, say, one inch from the transmitter, the amplitude of the recorded sound file could be measured for a group of several transmitters, a plot drawn for weak vs strong transmitters and after that, a new transmitter could be checked not only to see if it was working but also the strength of the transmitter.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on August 14, 2018, 06:21:49 PM
     Regular Member Post (http://www.classicrotaryphones.com/forum/index.php?topic=20151.msg206412#msg206412)

Continuing this topic, a couple of weeks ago, Ktownphoneco (Jeff Lamb) asked if I could run the data on an Audacity audio file (wave) containing the pulses from a suspect dial. The wave file he sent contained 6 full cycles (dialed 0 six times). He was in between Sage 930s at the time and needed to know if the dial on his bench was within spec.

I loaded the wave file and used the 2nd cycle, the second time he dialed 0. Using my Excel spreadsheet, found the dial was slow at 8.34 PPS and the Break/Make ratio was off at 69.64/30.36. When Jeff's improved Sage 930 showed up, he ran the dial to find the Sage had the dial at 8 pps and a Break/Make ratio of 70/30. Was nice to see the Audacity procedure was equivalent to the capabilities of a Sage 930.

When I found out both ways of testing a dial were similar, I again loaded the wave file into Audacity and analyzed all 6 of the cycles in the wave file. The purpose is to see the difference, or variation in a dial from cycle to cycle. Being a mechanical device, the gear action, governor, dirt and lubrication (or lack of) cause the dial to be slightly different in each cycle but by having the data from 6 cycles, the PPS and Break/Make ratio were found to be quite consistent, basically the same.

Having all this information and a greatly improved, over time, spread sheet, I am posting this to help anyone in the future who wants to use Audacity to check a dial's performance starting with the wave file for once cycle as seen in Audacity and how/where to read data from that screen to do the analysis.

The first image below is what is seen on a computer screen expanding the horizontal wave form to cover just one 10 digit cycle and pulling the bottom of the wave form bar downward to get a full screen view of the cycle.

The yellow circle in the upper left shows the start of a dial that will send 10 pulses, dial 0. The yellow circle below that shows the end of the first cycle, one pulse sent. The vertical change between this is the point at which the dial closed the pulse dials to go from a break to the make status. The lower yellow circle is also the first part of the next pulse, the opening of the contacts to produce the second digit "break." This continues for all 10 digits.

In the center of the wave form there is a vertical yellow line, this is the cursor as it looks within the wave form. The top bar shows the time in seconds and the position of the cursor is shown below in a box to the 1/1000th of a second. Placing the cursor exactly on a pulse spike will turn the pulse spike yellow and that exact point in time is shown in the box at the bottom. This is the number to be used in the Excel spreadsheet to analyze or test the dial.

Since there is no "break" after the last pulse, the "make" for the last digit dialed, the wave form trails off and this happens on every dial. There is no need to estimate or calculate the last, missing spike in that the time from the first "break" spike to "break" spike of the 9th pulse can be used and the time between those points divided by 9 to get the PPS rate of the dial. The information for the last digit is not needed for a PPS measurement.

A dial in spec will have that last "break" spike (the end of the 9th "make") exactly 0.9 seconds from the first "break" spike. Simply divide 9 (digits) by 0.9 seconds (the time it took to create the 9 full pulses) to get the speed of the dial in PPS, pulses per second. 9 divided by 0.9 seconds is 10 or the dial is running at 10 pulses per second (10 PPS).

A dial taking MORE than 0.9 seconds between the first "break" spike and the beginning of the 10th digit "break" spike will be running slow, less than 10 PPS. 

A dial taking LESS than 0.9 seconds between the first "break" spike and the beginning of the 10th digit "break" spike will be running fast, more than 10 PPS.

=============================

The data from the 2nd of the 6 cycles was plugged into my spreadsheet, second image below.

The green box in the upper left shows the dial speed for that cycle. 8.35 PPS, too slow.

The red box just below that shows the Break/Make ratio for the first pulse, 69.03%/30.07% with the spec normal at 60/40 ratio.

Since there is no 11th Break, the 10th Make trails off and the length of the 10th Make cycle can not be read. This last value was calculated from by adding the length of the first 9 Make times, finding the standard deviation of those values, dividing the standard deviation in half and adding it to the length of the 9th Make cycle length, the yellow box. In this case, 0.001 second was added to 0.039 seconds to estimate the 10th Make cycle length to be 0.040 seconds. This value is used to determine the 10 Break/Make cycle.

The graph below the yellow box show the time of each pulse. This plot always slopes up and that shows the dial spring winding down, less tension so slower speed. The slope itself is an indication of how dirty the dial is. A clean dial will have a rather flat slope and a dirty dial upward and even curved upward during the last couple of digits. It's an interesting graph when the dial is so dirty that it does not return to its stop or rest position by itself. In a perfect world, this graph would be flat at 0.1 seconds per pulse or 1.0 seconds for 10 pulses, the spec speed or 10 PPS. The dial speed of the first pulse was 0.115 seconds and the final pulse took 0.132 seconds showing the slowing of the dial about 15% over 10 digits.

The tall red box on the right is used to determine the Break/Make ratio of each pulse to get an average Break/Make ratio for the dial. In this 2nd cycle of 6, the average Break/Make ratio was 69.18%/30.82%.

The above data was obtained for each of the 6 cycles available for this dial. The 3rd image below shows the speed graph for each cycle. There is some variation for each pulse in each cycle but they are basically the same. The points above or below the calculated slope line can be a small piece of dirt getting in the gears for one pulse in any one cycle. That's why those outliers are not consistent from cycle to cycle. The slopes of each 6 graphs are consistent.

The last image below shows the data gathered from each of the 6 cycles. The top line is PPS and it is quite consistent from cycle to cycle with the average being 8.37 PPS +/- 0.04 PPS. The Break/Make ratio for the first pulse and the average of all 10 pulses for each of the 6 cycles is also quite consistent 69.3%/30.7%.

Again, the Sage 930 stated the dial had a PPS speed of 8 PPS and a Break/Make ratio of 70/30. Assuming the Sage 930 rounds, 8.37 PPS would round to 8 PPS and 69.3/30.7 would round to 69/31.

All this work was done to prove to myself that Audacity can be used to quite accurately determine both the dial speed and its Break/Make ratio using just one cycle and the first pulse Break/Make ratio (no need to do all ten pulses or multiple cycles to get an average - one cycle of 10 digits recorded by Audacity and plugged into a spread sheet will provide the same information as a Sage 930, but for just these two specs).

=============================

And once the dial is cleaned and adjusted, Audacity or a Sage 930 can be used to see if the work brought the dial into spec or if further cleaning/adjustment is needed.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: HarrySmith on August 14, 2018, 07:26:10 PM
That's good info. Thanks!
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: dsk on August 15, 2018, 12:43:38 PM
A good analysis of the picture, and an excellent explanation of the process!
I have done it simpler, and got pretty close numbers.

I played a little with the picture to get closer readings, and found the values written under the boxes marking out break no 1,2,9 and 10.

Those numbers are putted in to my online spreadsheet: https://goo.gl/9Pzxt5 (https://goo.gl/9Pzxt5)

and I got Speed 8.33 pps and a break/make ratio of 69.23/30.77 So I hereby confirm that you are right!

Do you need help? take a look here: https://goo.gl/w2apmG


dsk
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on June 13, 2022, 03:57:42 PM
I installed one of there inexpensive external USB sound cards for dial speed testing.

(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;attach=255238;image)

https://www.ebay.com/itm/313578863726

I was working on a WE 7D dial that to my surprise tested at 11.26 PPS as its "as purchased" dial speed.

The process of adjusting the dial speed is to remove the spring from the center of the governor (using a fine pointed tweezers to unhook one of the ears (red circles) from the governor wings and removing the spring.

(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;attach=255240;image)

Adjustment is to either 1) reduce the spring tension to slow down the dial (with less tension the wings open easier or sooner and slow down the governor and slow down the dial speed) or, 2) increase the spring tension to speed up the the dial (with more tension, the wings open harder or later and speed up the governor and speed up the dial speed).

It's a trial and error process. In this case, the dial was fast so the first attempt was to loosen the tension. There is no way to know how much the adjusted spring will change the dial speed.

In my first attempt to slow down the dial by decreasing spring tension (A), the dial dropped from its original 11.26 PPS to 9.20 PPS, in spec but too far from the ideal 10 PPS.

The second attempt (B) was to put more tension in the spring and the speed changed to 11.04 PPS.

The third attempt (C) was to put less tension to slow down the dial speed and it dropped to 9.51 PPS. This could be acceptable to some but being on the low side of 10 means that if the dial slows down in the years going forward, it could drop closer to 9 PPS. I prefer to adjust dials so they are a bit more than 10 PPS.

The fourth attempt (D) put more tension into the spring and it tested at an acceptable 10.24 PPS.

I got lucky with just 4 adjustments in that I have had to adjust dials 5 or 6 times to get them in my spec. I've also been lucky a few times in hitting the "just a bit more" than 10 PPS on the first adjustment. In bending the spring by hand, there is no way to know how much tension was put in or taken out of a spring until the spring is re-installed and the dial speed tested.

The Break/Make ratio for this dial tested at 61/39 so no need to adjust that dial mechanism.

I normally don't keep each Audacity wave form for each adjustment but this time I did to show how the trial and error method looks on paper. The thin yellow line shows the speed swings from slow to fast to slow to the final 10.24 PPS dial speed.

The red vertical line on the left is the start, the red vertical line on the right is where the 9th pulse would occur if the dial was returning at the perfect 10.0 PPS. When testing dials using this hardware and software, only the first 9 digits when dialing 0 (ten) is performed so a perfect 10.0 PPS dial speed would have the 9th pulse occurring at 0.9 seconds from the start of the dial return. In this diagram, the dial starts to return at 0.2 on the chart and would stop 0.9 seconds latter (1.1 seconds on the chart). You can see how the trial and error process moves the dial speed from one side of the perfect line to the other.

(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;attach=255241;image)

PS: The top scale of 0.2 to 1.1 is arbitrary, could be 1.3 to 2.2, and came to be by cropping the wave forms during post recording processing.


Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: SUnset2 on June 14, 2022, 12:31:57 AM
I apologize for hijacking this thread, but I can't find a better spot.  I have a 50AL that gives correct dialing on the BK tester, but I get dialing errors when I connect the phone to the fiber adapter.  I measured the dialing speed using an oscilloscope.  It turns out to be running a little over 14 pps.

So, I am trying to figure out how to adjust the governor on a WE No. 2 dial.  I found a thread on here that referred to BSP 501-162-100, which shows how to adjust the governor on a No. 5 dial using a 260 tool.  I don't know if this applies to a No. 2 dial, and I need to know how to do it without a 260 tool. 

Any advice?
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on June 14, 2022, 04:06:05 AM
A WE #2 dial has the same governor as a #5 dial.

The governor has an arm the pivots on one end and has an adjustment screw at the other end. Just above the screw are adjustment markers.

ABB03C00-F54A-4DF8-B4B6-E0954DCF6C6A.jpeg

There was a tool but it can be adjusted without it by using a small screwdriver.

Simply loosen the screw a bit so the screw end of the arm can be moved left and right.

I forgot which way slows down the speed so look at your governor and if the arm is off to one side, move it to the middle, tighten the screw and retest the speed (if the arm is near the middle already, someone may have gotten oil inside the governor raceway and that prevents the governor braking - in that case you will have to remove the oil with lacquer thinner and when clean and dry, retest the speed).

Keep doing that, moving it a bit each time left or right, until you get it close to 10 PPS.

Here's a topic with a picture of the governor removed from its race way. You do not have to take anything apart to do this adjustment.

http://www.classicrotaryphones.com/forum/index.php?topic=2918.msg39423#msg39423

Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on June 14, 2022, 08:53:47 AM
Another thing to check first is movement of the 2 wings in the governor.

Use a toothpick to see how easily they expand. If they seem sticky (a very, very rare occurrence), the pins they pivot on (one pin on each wing, the rose heads seen from the top), need lubrication but be careful not to get the lubrication inside the race.

If the wings open easily, the next step is to clean any lubrication out of the race with lacquer thinner and then put a small amount of lubricant on each pin, between the metal adjustment arm and the wing.

Then use the set screw to adjust the speed.

Your governor could need any or all of the 3 steps.

Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: countryman on June 14, 2022, 01:25:05 PM
Quote from: TelePlay on June 14, 2022, 08:53:47 AM... clean any lubrication out of the race with lacquer thinner ...


You might also want to try brake cleaner as used in auto shops, it comes in spray cans. It evaporates clean and very fast and is safe on many materials, yet not on all kinds of plastic. It's made to remove gummed up grease easily.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: SUnset2 on June 16, 2022, 01:05:14 AM
I cleaned the governor as well as I could using naphtha in case it was oily.  I verified that the wings pivoted smoothly.  I retested, and the speed was the same.  I could see that the screw was almost at one end of the slot.  I jammed the governor in place with two toothpicks, loosened the screw, and moved it most of the way to the other end of the slot.  I tightened it and re-measured the speed.  9.94 PPS.  Close enough.  I connected the phone, and was able to dial out without error. (Note that the picture is a different scale, both horizontally and vertically).

Thank you for the excellent advice.
Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on June 16, 2022, 04:09:55 AM
Excellent!

Strange that it was set so fast but glad you were able to get it close to 10.

Title: Re: Setting timing on a dial - A discussion of Analytical Instruments and Audacity
Post by: TelePlay on November 20, 2022, 01:38:04 PM
Sometimes this old stuff amazes me. Got a 1972 WE Princess some 8 to 10 years ago, put it into a box then, opened it yesterday and tested the dial. Untouched since built, the dial tested at 9.92 PPS with a 60.4/39.6 Break/Make ratio.

I tested the dial by connecting my USB external sound card directly to the red and green prongs of the 4 prong line cord connector still on the original round line cord. The phone was on my bench and I used a 50' long modular cord to get the pulses from the phone to my USB mic in connecting harness.

The set up here is annotated. The external USB sound card required a stereo mic plug so cut the ear buds of off a set of earphones, soldered the red and green stereo connectors together and use those along with the black ground wire to connect to the phone dial.

The connection can be made on the dial pulse terminals, on the network where the pulse wires are connected, the red and green wires of a modular Jack used as an adapter for a modular line cord, the red and green prongs of a 4 prong plug or on the dial pulse wires found on newer dials.  I used a loose WE 5H dial I had laying on my bench just to show the set up. This was not the dial in the Princess (a #8 IIRC, never took it out of the phone).

I simply open Audacity, select the input as the USB card, start record and dial 0 six times. I select the 3rd or 4th set of data points for analysis.

In this dial's case, the audacity waveform was clean and clear. Inputting the Audacity times into my Excel spread sheet showed the dial was working at 9.92 PPS with a 60.4/39.6 Break/Make ratio.

Rarely can I get a dial close to perfect spec after cleaning and adjustment. To find one as removed from service probably 30 to 40 years ago still factory perfect if remarkable.

This reply is basically to show how easy the interface from dial to computer is, how easily the data can be collected and how accurate the results are using a simple Excel spreadsheet (note, the last "make" point tails off and can not be read so 9 full break/make cycles are input into the spreadsheet and the speed normalized to 10 cycles).

No need for anything other than a computer with Audacity (free software), clip wires, an external USB sound card (to protect the computer internal sound card) and a simple harness to connect the USB mic in to the wires coming from the dial.