Introduction; Input Circuit Operation; Base-Band Video Processing; A1 And A2 Audio Demodulators - RF Central RFX-RMR Operator's Manual

The RFX-RMR X-0101 board provides the analog receiver function of the RMT digital / analog
receiver system rack assembly. The board provides one (NTSC) video output and two audio outputs.
Operation modes and audio sub carrier frequency selection is via front panel control. The R.F. input to
the board, at 70MHz, is taken from the system common digital / analog IF / AGC circuit via a passive
splitter network on the unit motherboard. A range of video processing options are available via front
panel selection or on-board switches. On-board LED's are provided for audio 1 and 2 phase locked
loop and power supply monitor functions.
8.1 R.F. input circuit operation.
The 70MHz R.F. input at Skt.1 is set to –17dBm nominal.
8.2

Base-band video processing

Provides facilities for video de-emphasis, black level clamp, automatic deviation selection, video invert
and audio sub-carrier filtering.
8.3

A1 and A2 audio demodulators

The nominal sub carrier input frequency ranges are A1 = 4.5 – 5.1MHz, A2 = 5.5 – 6.2MHz. The audio
demodulators have a 75uS characteristic, to match the pre-emphasis characteristic of the RMT
Transmitter.
RFX-RMR

8 INTRODUCTION

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