I'm trying to program via GPIB an HP 70000 series spectrum analyser, which has an 70004A display, 70902A IF section, 70900A local oscillator, 70905A RF section, 70310A high precision frequency reference and the 705700A digitiser.
If I try to set the span to 10 kHz or less via the GPIB, such as with the command string below.
IP;CF 918.000000 MHZ;SP 0.010000 MHZ;RL 0.000000 dBm;
the analyser goes to the setting I've put OK. The display show this, and every thing looks fine on the display. BUT if I then try to read the amplitude and frequency with:
the amplitude is read correctly, but nothing is returned for frequency. As soon as I set the span to over 10 kHz, it works just as I expect, and frequency is returned ok.
I've not set the format (TDF), so I assume it is the default, which looks like its ASCII decimal values.