Hello Andrew,
Thanks for the reply.
Does it mean that essentially SYST:PRES and SYST:PRES? affect the BB60C in the same way?
If so, the only difference between the two commands would be with or without returned value.
Please correct me if I’m wrong.

Hi Justin,
I’ve only tried zero-span mode with SA44B with video trigger level at 0dBm. Although the pulse energy is at 10dBm, you can barely recognize the 5uS envelope.
But I’m not interested in the absolute accuracy of the amplitude of the pulse. Rather, the central freqency measurement accuracy really matters in my application.
As my signal source has high Q value of about 15000.
Even a few 10KHz deviation of the peak central frequency detection is not acceptable.
I’m evaluating if BB60C is capable of delivering such central freqency measurement accuracy for the 5uS pulse.

Then what is the min. amount of points that each FFT does? Is it a fixed number? Or if it could be adjusted what’s the benefit of having FFT set to a lower amount of points?
In fact, I don’t care the activity changes in between pulses, because it’s certain that the signal is totally shut off when there is no pulse generated and the pulse’s central frequency won’t drift within such short period of time. That why I was asking if multiple pulses show up in the same sweep could do any help to the central frequency discrimination in the spectrum plot.
Could you explain more on this? Thanks.

Hi Andrew,
Thanks for the advice.
Based on your description, I’ve given up the SA44B.
Zero-span mode has little help to my application, as it only provides meaningful info. in time domain whereas my interest is the central frequency drifting performance of the carrier.
Let’s focus on the BB60C in real-time mode, I still have following concerns:
1. What is the IF sampling rate of BB60C?
2. Could you elaborate on “1.25 FFTs worth of data”? I guess it means 1.25 times the min. point of FFT which is (?) Would you do multiple overlapped FFTs within the same sweep time window?
3. When you mentioned “We accumulate ~30ms worth of spectrum before displaying the results in real-time which means you will see the accumulation of several pulses in your config in one sweep. ” I guess capturing multiple pulses within the same sweep time window is a good thing. Two seperate 5uS pulses is equivalent to one consecutive 10uS in terms of spectrum resolution providing the two pulses have the identical spectrum content. Am I correct?
Looking forward to your feedback.
Thanks a lot.

Best Regards,
bittware

Hi Justin,
Thanks for the reply.
I tried the zero span with video triggering. It worked very well.
But it seems to have no peak mark tracking capability that realtime mode has.
I also tried realtime mode. It worked as well.
The peak frequencies captured by in these two modes really have good consistency.
Now I’m trying to readout the peak frequency through SCPI command. I read the manual which says the zero span mode is not supported by SCPI yet. So it seems I have to rely on the realtime mode.
As such, could you let me know what SCPI command I should use to get the peak mark frequency read from Spike?
Thank you very much.

Hi
I confronted the very same frustration.
Without using external trigger, how can we capture the pulsed RF signal, say 3GHz signal with 2uS pulse width?
The pulse repetitive frequency could be 100mS.
Wondering if realtime mode is able to capture such narrow RF pulse?

If the center frequency drift is of concern, which API function should be used to get the instantaneous frequency measurement value？

This file is too big. The link is
http://www.analog.com/en/analog-dialogue/articles/rf-to-bits-solution.html

My signal generator is a magnetron so there is no time base to lock with. Then can I use the same signal with some phase shift as the time base to BB60C?
The scheme is something like what is shown in the attached file.

And what do you mean by “relative phase of the pulse”? Is it the phase varying with time within the pulse period or the fixed relative phase shift with respect to the reference signal?
My input is just pure 3GHz signal without any modulation.

It’s great to know BB60C could get it done.
Could you elaborate on “measurements on the instantaneous amplitude (including pulse width at 25 nanosecond resolution), frequency, and relative phase of the pulse.”?
In fact, I’m going to tune my 3GHz signal generator to my RF Cavity in real-time.
I’m particularly interested in what API may be involved to interpret the amplitude, frequency and relative phase. These three factors are the key to drive my tuner. How fast is the API running at the remote? Within 3ms interval, can all these three parameters per pulse be recorded without missing in streaming mode?
Thanks again.

Or this may be called instantaneous frequency measurement?

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