[time-nuts] Trimble T Lassen 2 - suitableantenna....advice.....questions

[Azelio Boriani]

Yes, the oscilloscope PPS detection is really a FAQ and already discussed
here. The use of a digital 'scope is recommended but the idea of dividing
the PPS by 2 with a FF is  useful and simple to implement, to detect if the
PPS output is working or not. A more "sophisticated" one uses a monostable
to stretch the 1uS pulse to 200mS to let it be solid visible. I use a
CD4538 with 22nF and 10K to give a good pulse visibility.

On Mon, Aug 20, 2012 at 8:44 AM, Tom Miller <tmiller at skylinenet.net> wrote:

> You can see it easily with any 50+ MHz analog scope that has a working DC
> trigger function.
>
> If it is a 1 us pulse width TTL output or close, set the H sweep to 1
> us/div, The vertical to 1 volt/div, the triggering to normal, and the
> trigger input to DC. Then adjust the trigger point to +1 volt. You should
> see a sweep every second. If you turn up the intensity and dim the room
> lighting, the pulse should be visible.
>
> If you are using a Tek scope and need help setting it up, just ping me and
> I'll assist. Others on this list can also give good advise in seeing this
> signal.
>
>
> Regards,
> Tom
>
>
>
> ----- Original Message ----- From: "Chris Albertson" <
> albertson.chris at gmail.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at febo.com>
> Sent: Monday, August 20, 2012 1:52 AM
> Subject: Re: [time-nuts] Trimble T Lassen 2 -
> suitableantenna....advice.....questions
>
>
>
> On Sun, Aug 19, 2012 at 9:27 PM, Robert Darlington <rdarlington at gmail.com
> >wrote:
>
>  It's a pain to capture on any scope, but really easy to see with an
>> LED across the output.  it's not bright, but definitely easy to see on
>> my tbolt.
>>
>
>
> That is true.  One must have very good eyes to see a one microsecond pulse
> that only happens one per second.  Blink and you miss it.
>
> The LED might work but the "for sure" way is to send the PPS to a flip flop
> so you can see the state change at 1Hz.  Use a solderless bread board and
> 5V power supply.
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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