The DSA800 series spectrum analyzers consist of the DSA815, DSA832E, DSA832 and DSA875. Each can come with or without a tracking generator.
The lowest level signal you will be able to see captured on a spectrum analyzer will be limited by the DANL or displayed average noise level so the lower the DANL the better.
To obtain the lowest DANL the DSA800 series analyzers will need to be operating within these parameters and settings:
Attenuation = 0 dB
RBW = VBW = 100Hz
Trace Average greater or equal to 50
Tracking Generator set to off
Normalized to 1Hz
Operating between 20°C to 30°C