[time-nuts] Using speaker / earphone for PPS testing (not a question)

Tue Apr 21 13:03:20 UTC 2020

TAPR offers a FatPPS kit to stretch the pulse out, and it looks like
they're back in stock. I have one but haven't assembled it yet.
https://tapr.org/product/fatpps-pulse-stretcher/

Larry

On Tue, Apr 21, 2020 at 8:17 AM Dana Whitlow <k8yumdoober at gmail.com> wrote:

> I've seen PPS ticks as short as 100 nsec from some equipment.  Didn't think
> to try the headphone
> trick at the time, but am dubious about hearing pulses that short at
> ordinary pulse amplitudes.
>
> Dana
>
>
> On Tue, Apr 21, 2020 at 6:37 AM Bob kb8tq <kb8tq at n1k.org> 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 <cburford1 at austin.rr.com>
> > 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 <time-nuts-bounces at lists.febo.com> On Behalf Of Taka
> > Kamiya via time-nuts
> > > Sent: Monday, April 20, 2020 22:35
> > > To: Discussion of precise time and frequency measurement <
> > time-nuts at lists.febo.com>
> > > Cc: Taka Kamiya <tkamiya9 at yahoo.com>
> > > 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 <
> > time at radio.sent.com> 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
> > >> _______________________________________________
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> > >>
> > >
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