I encountered a strange problem.
Signal need to be measurement: 12 sec length, 0.1 sec pulse (0dBm) and 11.9 sec noise (<-80dBm) at a fixed frequency (e.g. 16MHz).
I connect the signal to Port 1 and measured it as reverse A at CW mode.
The problem I encountered is:
(1) with 8712 and 5230A, the measured result (curve displayed) is exact what I expect.
(2) however, with 8753, the measured result is completely wrong: there should be only 1 pulse near 0dBm during one 12sec sweep, but 8753 displayed many, the noise also increased to -30 to -50dBm, furthermore, there are >1 pulses also near 0dBm.
I think the problem should be due to config/setting of the 8753. Anybody knows the difference between the 8753 and 8712/5230A settings which may lead to aforementioned problem?
Thanks!
Signal need to be measurement: 12 sec length, 0.1 sec pulse (0dBm) and 11.9 sec noise (<-80dBm) at a fixed frequency (e.g. 16MHz).
I connect the signal to Port 1 and measured it as reverse A at CW mode.
The problem I encountered is:
(1) with 8712 and 5230A, the measured result (curve displayed) is exact what I expect.
(2) however, with 8753, the measured result is completely wrong: there should be only 1 pulse near 0dBm during one 12sec sweep, but 8753 displayed many, the noise also increased to -30 to -50dBm, furthermore, there are >1 pulses also near 0dBm.
I think the problem should be due to config/setting of the 8753. Anybody knows the difference between the 8753 and 8712/5230A settings which may lead to aforementioned problem?
Thanks!
A key difference between the 8753 and the other two analyzers is that the 8753 uses a sampling down-converter (high harmonic) where the other two use fundamental mixing.
Sometimes the sampling down-converter can give alias responses due to signals sampled down from other frequencies. In the 8753, the fundamental LO is 30-60 MHz. This drives a pulse-generator which drives the samplers, so there is a mixing comb-tooth every 30-60 MHz, which down converts the signal to the IF. In a pulsed application, the pulse can produce many frequencies, and sampling might cause some unusual results.
I don't know if you can upload a plot of the 8753 resulsts as well as the others, but it would certaintly help to pinpoint the cause. You might also try a signal below 16 MHz, as 16 MHz is the magic frequency where the 8753 goes from LOW-BAND (fundamental mixing) to HI-Band mode (sampling).