Hi, 20us length is a mil standard. Described in ICD-GPS-060.
/Björn Sent from my iPhone > On 21 Apr 2020, at 13:37, Bob kb8tq <[email protected]> wrote: > > Hi > > One of the simplest justifications I can think of for a dirt cheap “Chinese” > digital ’scope is to capture short burst stuff like narrow pps pulses. > > 10 us / non-adjustable is a *very* common spec for a 1 PPS. > > Bob > >> On Apr 21, 2020, at 4:56 AM, Chris Burford <[email protected]> wrote: >> >> I reached out to SRS several months ago to inquire if the pulse width could >> be configured from the default of 10 micro second. Their responses was no. >> >> Chris >> >> -----Original Message----- >> From: time-nuts <[email protected]> On Behalf Of Taka Kamiya >> via time-nuts >> Sent: Monday, April 20, 2020 22:35 >> To: Discussion of precise time and frequency measurement >> <[email protected]> >> Cc: Taka Kamiya <[email protected]> >> Subject: Re: [time-nuts] Using speaker / earphone for PPS testing (not a >> question) >> >> Out of all signal source, the shortest 1 pps is PRS-10 at 10 micro second. >> T-bolt is quite short as well but I don't have a definite data. >> For those, speaker method worked just fine. I'm just sharing what I learned >> on happenstance. >> >> --------------------------------------- >> (Mr.) Taka Kamiya >> KB4EMF / ex JF2DKG >> >> >> On Monday, April 20, 2020, 11:05:02 PM EDT, Bill Byrom >> <[email protected]> wrote: >> >> It's easy to trigger on short pulses on most oscilloscopes if you follow >> these steps: >> (1) Do NOT use Auto Trigger mode. Instead use Normal trigger mode. >> (2) Set the vertical coupling mode to DC. >> (3) Set the vertical gain (volts/div) and offset so that the baseline (OFF >> voltage between pulses) and pulse ON voltage should both be visible on the >> vertical scale. >> (4) Set the trigger coupling mode to DC and the trigger source to the proper >> channel. >> (5) Set the trigger voltage to the midpoint between the pulse OFF and ON >> voltage. >> (6) Set the trigger slope appropriately, depending on the polarity of the 1 >> PPS pulse. >> (7) Many oscilloscopes have a trigger indicator LED. It should flash visibly >> on each 1 PPS signal. >> (8) If you are using an analog scope which does NOT have a microchannel >> plate (which was used on the Tektronix 2467 family and a few other models), >> the pulse ON signal may be difficult to see at a fast time/div setting, even >> with a high scope intensity setting. But you can slow down the time/div of >> an analog scope to something easy to see, such as 10 ms/div. This will allow >> you to see a bright sweep each time the scope triggers, even if a short >> pulse can't be seen. >> (9) When using a digital oscilloscope, turn on the peak detect display mode. >> This allows the oscilloscope to keep a high sampling rate even if the >> time/div is set for a moderately slow sweep. >> >> If the 1 PPS signal is very short, you won't be able to hear it on a speaker >> with a direct connection as you describe. But you can use a pulse stretcher >> circuit (such as a 555 timer IC) to drive a LED or speaker with a long >> output pulse (such as 10 ms). If you use two 555 IC's (or a 556 dual timer >> IC), you can even configure one section as a one-shot and the other as a >> tone generator so that a beep is produced for each pulse. The 555 and 556 >> may be sold as LM555/LM556 or NE555/NE556. >> -- >> Bill Byrom N5BB >> Retired Tektronix Application Engineer >> >>> On Mon, Apr 20, 2020, at 9:25 PM, Taka Kamiya via time-nuts wrote: >>> Maybe everyone but I knew, but I just did this and found it useful. >>> 1 pps signal from some GPS are notoriously narrow and difficult to sync >>> on and see on scopes. LED will barely light if some kind of stretcher >>> is not used. If your purpose is ONLY to see if it's there or not, hook >>> up a small speaker, earphone, amplified or not, and you can hear the >>> tick-tick sound. >>> >>> I like DIYing and many times, I wonder if pps distribution circuit is >>> working. I can tell a very short pulse that will barely register on >>> LED is clearly audible. >>> I thought I'd share. >>> >>> --------------------------------------- >>> (Mr.) Taka Kamiya >>> KB4EMF / ex JF2DKG >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >>> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> <1PPS - 1MΩ.png>_______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
