Signal To Noise; Principles; How It Is Measured - HP 4934A Operating And Calibration Manual

Signal to Noise
Principles
The signal-to-noise measurement determines the ratio of received signal-
plus-noise power to noise power and gives a measure of the margin between
the data signal and the background noise.
transmitter receiver
I EL; '•
S^GN
♦
NOISE ,
■
-
compare
1004 Hz
=;lter
' OMLY
How it is Measured
1 The transmitter sends a 1004 Hz holding tone at the nominal data level.
2 The receiver notches out the 1004 Hz holding lone and what is left is measured
via a filter (C-Message, 3 kHz Flat, 15 kHz Flat, Program or 50 kfiit) then
compared with the original signal-plus-noise. The computed ratio is displayed in
dB.
Making Measurements 2-15