QAM Marker
Signal Source
rev1.0.5 August 15, 2017
21
QAM Channel Measurement Reference Notes
Below are several reference points and calculations for both 6 MHz and 8 MHz QAM Channels.
QAM Symbols per Second or Signal Bandwidth (SBW)
6 MHz QAM
8 MHz QAM
64 QAM
5.057 MHz
6.952 MHz
256 QAM
5.361 MHz
6.952 MHz
Common Measurement Bandwidth Correction Factors for 256 QAM:
RBW
6 MHz QAM Correction Factor
8 MHz QAM Correction Factor
3 MHz
10 * log10 (5.361 / 3.0) = 2.52 dB
10 * log10 (6.952 / 3.0) = 3.65 dB
1 MHz
10 * log10 (5.361 / 1.0) = 7.29 dB
10 * log10 (6.952 / 1.0) = 8.42 dB
300 kHz
10 * log10 (5.361 / 0.3) = 12.52 dB
10 * log10 (6.952 / 0.3) = 13.65 dB
100 kHz
10 * log10 (5.361 / 0.1) = 17.29 dB
10 * log10 (6.952 / 0.1) = 18.42 dB
QAM Channel Power = Measured QAM Level + RBW Corr Log Averaging Correction
Additional Spectrum Analyzer Settings:
Detector Type - Sampling
References:
1
Agilent - Spectrum Analyzer Basics - Application Note 150
2
Agilent - Spectrum and Signal Analyzer Measurements and Noise - Application Note
3
QAM Marker User Guide
