Spectrum Analyzer unit
Posted: Thu Sep 03, 2020 9:34 pm
Hi,
I'm using the spectrum analyzer built-in app with Red Pitaya and I'm trying to understand the unit of the y axis. It says "amplitude [dBm]", I'm assuming that means the power in dBm (1 mW corresponds to 0 dBm). I'm hopping to convert this into voltage, and from the spec, it seems like the input impedance is 1MOhm. I tested it with a function generator generating a definite peak-to-peak sinusoidal wave (double check with another oscilloscope), but the numbers won't add up, i.e. the power calculated from dBm doesn't correspond to V_{rms or peak-to-peak}^2/1 MOhm. I also noticed that from the 'setting' in the spectrum analyzer app, one can choose 'dBm' or 'dBu' and even the input impedance. I'm confused. Can anyone help me with this? thank!
Allen
I'm using the spectrum analyzer built-in app with Red Pitaya and I'm trying to understand the unit of the y axis. It says "amplitude [dBm]", I'm assuming that means the power in dBm (1 mW corresponds to 0 dBm). I'm hopping to convert this into voltage, and from the spec, it seems like the input impedance is 1MOhm. I tested it with a function generator generating a definite peak-to-peak sinusoidal wave (double check with another oscilloscope), but the numbers won't add up, i.e. the power calculated from dBm doesn't correspond to V_{rms or peak-to-peak}^2/1 MOhm. I also noticed that from the 'setting' in the spectrum analyzer app, one can choose 'dBm' or 'dBu' and even the input impedance. I'm confused. Can anyone help me with this? thank!
Allen