[time-nuts] Nortel GPSTM TP13 positive or negative?

[EB4APL]

Hi,

I have a NTGS50AA, is this the model of your unit? If yes, I am very 
interested in the circuit diagrams since I have a very partial one, 
which I made by reverse engineering to bring the 1 PPS out, re-purposing 
the 9.8304 output circuitry since I don't have any use for it.

Regards,

Ignacio


El 13/04/2019 a las 6:29, Taka Kamiya via time-nuts escribió:
> There is a typo in my first post.
> TP13 as well as one pulse every 2 second output are negative logic.  Manual does not mention polarity of 2sPP.
> On this page: Nortel GPSTM - i3Detroit  if I'm reading the circuit diagram correctly (really a construction diagram), he seems to be inverting it once, then feeding it to parallel of another inverters.  If I do this, I get negative 1pps.  I cannot make heads or tails out of scope screen shot as I have no idea (I can only guess) which trace represents what output.  But green line is showing negative logic.
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> ---------------------------------------
> (Mr.) Taka Kamiya
> I'm stuck in a wormhole....  Hello, worms!
>
>      On Friday, April 12, 2019, 11:01:02 PM EDT, Taka Kamiya via time-nuts <time-nuts at lists.febo.com> wrote:
>   
>   I was fortunate enough to buy Nortel GPSTM at very good prices.  This is a distant cousin of Thunderbird as far as I know.  However, it being CDMA clock source, it's second pulse output is actually once every 2 seconds.  According to various Internet sources, TP13 on board is 1 PPS.
> I measured TP13 and it actually IS 1 PPS.  However, this test point is giving negative logic.  Normally +5V and it goes to 0V every 2 seconds.
> Manual does not say anything about this being PP2S (with a bar on top).
>
> Has anyone noticed this or am I doing something wrong????
> I cascaded two inverters (74AC04) and have used two gates to provide boost to obtain normally 0V and goes to 5V every 1 second.  It works but I am baffled.  Can anyone tell me what I am seeing is actually the way it is?
>
> ---------------------------------------
> (Mr.) Taka Kamiya
> I'm stuck in a wormhole....  Hello, worms!
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