Measuring UNB signal

Hi,

I need to measure the occupied bandwidth of a Ultra Narrow Band signal at 869 MHz.

The signal must comply with
-20 dBc @ +/-100Hz RBW 50 Hz
-40 dBc @ +/-300Hz RBW 50 Hz
-50 dBc @ +/- 500Hz RBW 50 Hz

The conditions are:
RBW = 50 Hz
VBW = 50 Hz
Sweep time : 6 s

I can set all parameters except the sweep time (6 s is not accepted by Spike). I thought to use the averaging function but I’m not sure of the setting.

Can you recommend a mean to measure such signal occu^pied bandwidth ?

Thanks in advance,

Fabrice

Hello Fabrice,

Unfortunately at this moment, the sweep times are limited in selection. You could try to simulate this in a few ways.

If you are looking for the peak occupancy of this signal, you could setup the peak detector with a max hold trace.

If you are using the average detector, you could lower your VBW which would increase sweep time and use trace averaging.

You could use the average detector setup to get your channel power to create your mask, and then the peak detector setup to ensure no violations occur, if this is in fact your task.

Regards,
A.J.

Hello Andrew,

Thanks for the answer. Using trace averaging finally gives a good result.

I have a remaining question about trace averaging. Is the averaging performed on the linear power signal and then displayed in log scale or is the trace averaging performed on all log traces directly (i.e. log of the average or average of the log) ?

Thanks again for your valuable help.

Best regards,

Fabrice

PS: I’m discovering the BB60C instrument and its dynamic range and frequency stability are excellent. Good job!

Hello Fabrice,

The trace averaging, (aka setting the trace ‘type’ to average) is simply an average of the log traces, (average of the log).

Let me know if you have any other questions. Thank you for the kind words.

Regards,
A.J.

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