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5372A: problems to measure TI from 1pps output of the Rockwell Jupiter GPS

pete_electro All Messages By This Member #71367 Hello, I have been given an old Rockwell-Jupiter GPS based on the Zodiac chip. It came with an interface-board from System Electronics. AFAIK the 1pps and 10KHz are only wired through. Especially the 1pps output is sensitive to loading - I have to put in a 10K series resistor to not stop it from working when connected to the 50 ohms input pod of the 5372A. While I can measure the time interval of the 10KHz signal with the 5372A, i can not do so with the 1pps signal. As it can be seen on a scope, this signal is high (4.5V) most of the time and goes down to GND for about 25ms every second. I tried a lot of adjustments in the function menu (i.e. long sample intervals) and in the input menu and also another input pod (54001, 10K input R) without success. Any ideas? best regards Peter ?
czelusniakd All Messages By This Member #71369 You did not give a model number,. Pins may be different on your model. TU30-D140 pin 19 "1 PPS (puls per second) signal. This is a TTL signal with a frequency of exactly 1 Hz. The pulse length is exactly 25.6 ms and the rising edge is within 1us from the UTC second transition. There is software available that synchronizes the time in your PC and that expects a 1pps signal on the DCD line." "pin 20 10 kHz TTL signal. This signal is also synchronous with pin 19 and has a long-term accurate to 1uHz (microhertz) or better, if the receiver has a "fix" on the GPS satellites" -------------------------------------------- toggle quoted message Show quoted text On Mon, 9/14/15, peter@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote: Subject: [hp_agilent_equipment] 5372A: problems to measure TI from 1pps output of the Rockwell Jupiter GPS To: hp_agilent_equipment@... Date: Monday, September 14, 2015, 12:06 PM Hello, I have been given an old Rockwell-Jupiter GPS based on the Zodiac chip. It came with an interface-board from System Electronics. AFAIK the 1pps and 10KHz are only wired through. Especially the 1pps output is sensitive to loading - I have to put in a 10K series resistor to not stop it from working when connected to the 50 ohms input pod of the 5372A. While I can measure the time interval of the 10KHz signal with the 5372A, i can not do so with the 1pps signal. As it can be seen on a scope, this signal is high (4.5V) most of the time and goes down to GND for about 25ms every second. I tried a lot of adjustments in the function menu (i.e. long sample intervals) and in the input menu and also another input pod (54001, 10K input R) without success. Any ideas? best regards Peter
[email protected] #71370 > "pin 20 > 10 kHz TTL signal. This signal is also synchronous with pin 19 and has a long-term accurate to > 1uHz > (microhertz) or better, if the receiver has a "fix" on the GPS satellites" > I would expect long-term accuracy much better than 1 uHz. AFAIK, the 1 Hz and 10 KHz signals may be used for 1 x 10E-11 or even better adjustments. Jitter in the signal or the receiver should also even out for long-term observations. It depends on what one calls long-term I guess. Raymond
pete_electro All Messages By This Member #71371 Hi, thanks for your suggestions but my question aims in the direction of using the hp 5372A. I have a description of the GPS and the interface-pcb and I am taking the signals right from there. I can see the 1pps very good on the scope but I am not able, to measure the 1pps with the hp 5372A. Maybe it is a wrong matching from the 1pps output to the 5372A input or I am just doing something wrong with the 5372A. I looked in the manual and tried a lot - now I have no more ideas. - Peter Btw. the 10KHz signal shows an interesting time interval histogramm: almost discrete lines left and right from the ideal value of 100?s: at about 99.99?s and 100.008?s. ?

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