The 51RV-4B is a solid-state, airborne navigation unit thatcombines the VOR, localizer, and glideslope functions. The dual-conversion200-channel VOR/LOC (108 to 118 mHz with 50-kHz channel spacing) and 40-channelglideslope (329 to 335 mHz with 150-kHz channel spacing) receivers areremotely controlled by 2-out-of-5 binary or by serial information transmittedin ternary broadcast form. The 51RV-4B has the capability ofdual-instrumentation circuits with internal comparison and level monitoring;other options available are self-test functions, digital bearing output,added filtering of the basic bearing information, serial tuning, RMI servoamplifier, and heads up display driver capability. 

The 51RV-4B VOR/ILSNavigation Receiver receives VOR, localizer, and glideslope signals andprovides outputs to operate deviation, flag, and to-from indicators; and tooperate the VOR pointer of an RMI (radio magnetic indicator). The 51RV-4Boperating frequencies are 108.00 to 117.90 mHz for VOR/LOC and 329.15 to335.00 mHz for glideslope. When tuned to a VOR frequency, the 51RV-4Boperates with an external course indicator that provides a 400-Hzelectrically zeroed course resolver. Outputs from the 51RV-4B operate VORdeviation and to-from indicators, a VOR warning flag, a relative bearingindicator (RMI), and supply an aural output. The 51RV-4B is capable of beingtuned 2-out-of-5 binary control or serial tune input. A digital VOR bearingword output provides for operations of digital instruments and systems. The51RV-4B adds expanded monitoring in the VOR/ILS functions. The -201 status ofthe 51RV-4B provides the heads up display capability.