SP145 wrong amplitude reading and IF overload

Mehdi,

You specify an attenuation of 0dB, which for the SP145 I believe is overriding your reference level control. If you want reference level to control the sensitivity of the receiver we recommend leaving all gain/atten/preamp values to their defaults. The reference level control alone will properly set these controls behind the scenes for the best dynamic range. If you change attenuation back to Auto, with a ref level of 0dBm, your measurement should work again on the SP145.

The reason you probably don’t see the same issue on the BB60D is because you have to set both gain and atten before it override the Ref level. Again, we still recommend leaving everything auto and just using ref level, unless you have a specific reason not to.

A reference level of -20dBm on the SP145 achieves the minimum noise floor, but will limit input signals to ~-20dBm before IF overload occurs. On the BB60D, the minimum noise floor is achieved at -30dBm reference level.