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# How do I include Mismatch Uncertainty into the N5530S Measuring Receiver Absolute Amplitude accuracy?

The N5530S Measuring Receiver System is comprised of a PSA Series Spectrum Analyzer, an EPM Series Power Meter, an N5532A Sensor Module, and N5530S Measuring Receiver Software.

1. Convert the N5530S Absolute Amp Spec to Linear value.
2. Divide by the coverage factor (K = 2.57) to get 1 sigma.
3. Calculate the Source Mismatch error (1 sigma).
4. RSS the Abs Amp and Mismatch terms.
5. Multiply by the appropriate coverage factor (K).
6. Convert the Linear result to dB.

### Source Mismatch Calculation Example

Assume we are measuring a 2 GHz, -20 dBm signal. The N5530S Absolute Amplitude Accuracy is ± 0.124 dB. The Sensor Module VSWR is 1.28:1 (rho = 0.122). Assume the source VSWR is 1.5:1 (rho = .2).

1. Convert Abs Amp to linear (%): 100 x [ 100.124/10 -1 ] = 2.90%
2. Normalize to 1 Sigma (K= 2.57): 2.90%/2.57 = 1.12%
3. Determine Mismatch error: 100% x (0.2) x (0.122)/Sqrt(2) =1.74%
4. RSS the terms: Sqrt [ (1.12)2 + (1.74)2 ] = 2.07%
5. Multiply by the appropriate coverage factor (K): 2.57 x 2.07% = 5.31 %
6. Convert % to dB: dB = 10 x Log[ 1 + (5.31/100)] = ± 0.225 dB