What was carrier frequency, real carrier level and modulation frequency and depth % in previous Rigol example?
Here:
Siglent SDS1102X(+)
Input 50ohm, signal 5kHz sine carrier level -6dBm, AM with 1kHz sine and modulation depth 50%.
Scope run normally and stopped for looking history buffer and there was 93 last horizontal sweeps. (biggest number is last acquisition) Displayed here frame 37 (56 back from stop moment. FFT. FFT level Ref -3dBm. 10dB/div. Horizontal 2kHz/div. (manually moved center for 7kHz)
For low frequency (audio) FFT analyzing I will recommend - just sound card and some good software. (if your signal is suitable for these)
For RF analyzing. Real SA.
If use scope what have limited processing power for FFT and very limited data length for FFT there is other way. If in hobby use one have time and time is not money, as it is in profession works. I do not know how in other scopes but with Siglent, just insert USB stick and save waveform .CSV. (Or transfer using PC with EasyScopeX) Then use what ever suitable software for FFT (or what ever kind of analyze) (Warning: 14Msample .CSV file is - huge. Look your software limits)
if push "Math" button there can see FFT current settings. Cursors can use for FFT (selecting cursor source Math instead of CH1 or CH2 or Ref A or Ref B). In this image level is dBm, scale 10dB/div and Reference (top) level -3dBm.