User Guide

TRANSCEIVER

11/97JR

7–4

NHC–4

Technical Documentation

Technical Specifictions

Modes of Operation

NHC–4 operates in three modes:

1. In AMPS mode it operates in analog control and traffic channel

2. In digital mode in digital traffic channel

3. Test mode, which is used by Production and After Sales.

Control Channel Operation

In normal standby the terminal receiver, UHF frequency synthesizer and MCU

are powerd on continously and the receiver is monitoring the incoming signal

constantly. DSPs and MCU are in clock stop sleep. MCU is woken up every

46.3 ms by the RX modem.

In extended standby the terminal receiver and UHF frequency sythesizer are

powered on only for the time of incoming data bit and frame synchronization

and for the time of the first data repeat. DSP and MCU are in clock stop sleep.

MCU is woken up and DSP and MCU clocks are switched on twice every 46.3

ms by the RX modem. If the parity check of the first repeat of the incoming data

is correct, MCU and RF receiver and sythesizer are powered down untill the

next interrupt. If the parity check shows errors, the extended stanby mode is

disrupted and normal standby mode is resumed until several correct consecu-

tive frames have been received.

Out of range operation (OOR) is used, when terminal fails to syncronize to any

control channel after 15 s of scanning. During the scan the terminal receiver,

UHF frequency sythesizer and MCU are powerd and clocked as in normal

standby and in sleep they are power down like in extended standby. After being

40 s in the OOR mode the terminal scans control channels for 2.6 s. If synchro-

nization is aquired then stanby mode and SERV are resumed. if no synchro-

nization is found, then the terminal goes to OOR state for another 40 s etc. If

any button of the terminal user interface is pressed during OOR mode, the ter-

minal performs a rescan. OOR mode is not entered, when the terminal is con-

nected to any charging device.