For all thinkRF RTSA, the amplitude accuracy is +/- 2dB typical. Typically refers to 90% of the time, which means 10% of the time amplitude may fall outside of the specification. 

Here is a simple way to verify the amplitude accuracy by using ThinkRF S240v5 v5.1.3 Real-Time Spectrum Analysis Software

  1. Injecting a clean CW signal at any frequency within the range of the RTSA at -44dBm. 
  2. Set the S240 configuration as follows:
    - centre frequency aligns with the injected signal
    - Span at 40 MHz
  3. Use peak search to find out the amplitude value of the input signal
  4. confirm whether it is within the 2dB limit
  5. continue on another frequency

Users can also apply their own calibration to correct the amplitude readying if the calibration is out of spec or expired. more can be found here: AppNote: How to Perform a Custom Calibration on a ThinkRF R5xx0