CHAPTER 3 FUNCTIONING OF EQUIPMENT

TM 32-5865-069-24&P

CHAPTER 3

FUNCTIONING OF EQUIPMENT

3-1. SCOPE. This chapter provides a functional description of the RSPU and its

modules and circuit card assemblies. It is to the level required for support of

units tested by the AN/USM-410. The descriptions are keyed to functional block

diagrams. Refer to TM 32-5865-060-24&P, System Maintenance Manual, for a detailed

system interface description.

3-2. RSPU FUNCTIONAL DESCRIPTION. Refer to FO-1, a functional block diagram of

the unit. The RSPU provides the following functions:

a. An interface between the four digitally tuned and controlled VHF receivers

housed in the Receiver Set (RS) and other units of the AN/MLQ-34 system.

Four Carrier Presence Detectors (CPD), each monitors the Narrow-Band IF

(NBIF) input from a dedicated receiver. When a signal is present in the receiver,

CPD outputs are used to provide activity indications (computer interrupts, front

panel lamp, and status data transmitted on RC Bus A).

c. Four NATO tone detectors monitor the auxiliary audio signal inputs from the

receivers. These detectors determine the presence of the NATO tone in the receiv-

ed signal. Indications that the tone has been detected are provided to the system

(computer interrupts, front panel lamps, and status data transmitted on RC Bus A).

d. A signal data processor converts either the Wide-Band IF (WBIF),

or video,

from the RS into digital representation of the frequency spectrum. The

digital

data output is transferred on RC Bus B to provide 128 data points for a

remote

panoramic (PAN) display. Control of PAN display data processor is also

trans-

ferred on RC Bus B.

These functions are described in the following subparagraphs.

3-2.1 RC Bus A Interface. Receiver control and tuning are determined by data

transferred on the serial data bus RC Bus A. When the system is in the PRIMARY

mode, the bus is controlled by the system CPU. When the system is in the BACKUP

mode, the bus is controlled by the RCDU. The bus is routed to the RSPU and buf-

fered on RC Bus Status Interface CCA A6. The buffered output is used to drive the

four receivers in the Receiver Set. In addition, the control interface (P/0A6)

monitors the bus. When the receivers are bein addressed, the control interface

collects data from the bus. Receiver address bit 3 and bit 4), IF bandwidth

control (bit 6, bit 7 and bit 8) and carrier presence manual threshold (bit 55)

are decoded and used to control CPD A1-A4. When the RSPU is addressed (polled for

data), the status interface (P/O A6) drives status data onto the bus. Status

inputs to A6 are; TONE STATUS from each tone detector, CPD LOCAL from each

detector, RS PWR and RS TEMP STATUS, RSPU PWR and RSPU TEMP STATUS. The 5 MHz

reference input from the RS is buffered by A6. RC Bus timing is described in

3-1