quaestion about asynchronous spectrum analyzer and sweep generator...

[auato]

Hello everyone.

I don't find any way to talk my spectrum analyzer (HP 8595E) with a Wiltron programmable sweep generator. I already tried all combinations and read two service & operator manuals but... nope. Tried to drive the sweep generator using the exiting sweep ramp from the spectrum analyzer or vice versa to drive the S.A. by the sweep generator using its TTL external trigger.... nope! Anyway I have not been successful until now.
But my question is to clarify what I'm looking on my S.A. monitor, now. Indeed connecting the sweep generator to the S.A. with a simple 50 Ohms coax cable I expect to see an horizontal line along the X axis of the CRT and leveled at the output amplitude of the signal outgoing the sweep generator (0dBm) or somenthing that sounds like an horizontal line. Well, I obtain something of similar only when I set the sweeptime of my S.A very slow against a sweeptime very fast for the sweep generator. For instance, I only see something decent if I set almost 20 seconds on the S.A. (but the marker is very slow) and when I set the sweeptime for the generator as much as faster possible (10 milliseconds).



I wonder what I'm seeng on the CRT of spectrum analyzer in this case... two independent instruments to run free, only connected by a coax cable. The sweep generator sweeps the RF frequency from 10MHz to 12.4GHz at about 0dBm with a speed of 10msec. and the spectrum analyzer scans the spectrum from 9KHz up to 6.5GHz every 20 seconds. I am not able well to figure out in my mind what I am watching on the S.A. CRT. Is it a reliable frequency response that? ... just to trim some filters/cavity or to look some line transmissions behavior.
And if you are some tip to help me how to talk two tools each other (or you already know those instruments), I really appreciate it :razz:


Regards
Ciro

 

[tgootee]

I think that you would need to sweep the generator through at least one whole sweep, for EACH POINT of the spectrum analyzer sweep. Either that or you would need to use Max Hold on the spectrum analyzer and wait for a very long time. The first way takes a long time but at least it's guaranteed to end with believable results at a specific time.

I hope that you can figure out how to get them synchronized. Maybe you could use a separate function generator, to experiment, to see what signal WILL work, for that. Then you might find that you would only need some simple opamp circuit to condition one of your control signals, to make it work with the other unit.

 

[jiripolivka]

Instead of synchronizing both instruments you can either sweep fast and analyze slow, or reverse. Use MAX function to accumulate responses over the repeated sweeps.

 

[biff44]

you could control both from a computer, or set the spectrum analyzer for "max hold"

 

[auato]

Thanks everyone. I would like control both but it is not simple at all.. tought I have many signals outgoing the instruments like ramps, pules, triggers and so on and the possibility to switch both for external triggers or external ramps control functions... but I already spent two days playing with and no any success happened. However, tomorrow I'will try again with the max hold function that I have to study better, and I will inform you.

Thank you