Service manual

STP 11-25R13-SM-TG
S - 41
Figure S-41. SIN
2
Pulse and Bar Test Signal (continued)
S-32. Noise.
Noise encountered in a TV system is usually of the type called white or flat noise, which contains
equal amounts of energy over a wide frequency spectrum. This noise mixes with the TV signal to
produce unwanted distortion.
a. Accurate measurement of noise is necessary to determine the amount of noise added by each
stage of the TV system. The 147A and 1430 waveform monitors measure noise by deleting a portion of
the incoming signal and inserting a known amount of noise from the internal noise generator. The noise-
level dB switches control the amount of noise inserted; when the inserted noise matches the incoming
noise, the amount can be read directly from the noise-level dB switch settings. This method is accurate
within 2 dB. See Figure S-42.