[time-nuts] Why are 1PPS signals so skinny?

Azelio Boriani azelio.boriani at screen.it
Mon May 14 20:14:47 UTC 2012


OK, thank you for the references.

On Mon, May 14, 2012 at 9:20 PM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> Mark, Azelio and Björn,
>
> On 05/14/2012 06:33 PM, bg at lysator.liu.se wrote:
>
>> Mark&  Azelio,
>>
>> Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
>>
>>     http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
>>
>> More modern 3-5.5V into 50ohm, 20us.
>>
>> http://contracting.tacom.army.mil/majorsys/jab/DAGR%20Interface%20Specification.pdf
>>
>> Above are two standards demanding short skinny 1PPS pulses. Are there any
>> other standards with distinct shape requirements on 1PPS pulses?
>>
>
> You need to look at MIL STD 188/155 which if I recall things was initially
> formed in the 60thies.
>
> An AccuBeat presentation actually says that the PPS was originally defined
> in it.
>
> The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
> than we are used to know. It specified 5 MHz as base frequency, or power of
> 2 multiples (10, 20, 40 MHz... ).
>
> It was later reformulated in the PTTI spec, which ICD GPS 060 is a
> derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
>
> I was not able to find MIL STD 188-155 on the net right now, but I have
> been able to download it before, so if someone is a more lucky it should
> surface. I should have my download somewhere.
>
> Cheers,
> Magnus
>
>
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