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

[Bob Camp]

Hi

I would bet that the basic electrical definition of the "skinny" PPS dates at least to the mid 50's if not earlier. 

Bob

On May 14, 2012, at 3:20 PM, Magnus Danielson 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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