Guardian G25AMK005, Technical Manual

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G U A R D I A N V H F 1 1 0 W M O B I L E 3-5
3.2.3.8 Receiver Scanning
In some scanning modes it is necessary for the radio to scan a number of channels looking for traffic, as controlled
by the H8 software. The basic requirement is to change the synthesizer frequency, RXVTF, synthesizer tune DAC,
and to resume searching on the new frequency. The DSP may have to be informed of new traffic settings on which
to search, for each new frequency. Scanning is interrupted when the DSP detects a signal of interest.
3.2.4 DC Power Control
The H8 controller software controls the power supply switching in the radio. The control software algorithm uses
the following inputs:
Input Description
/PWROFF Indicates the current position of the radio on/off switch and the accessory connector off line
WRU Indicates if the radio is fitted into a harness providing external power
/LBOUT Indicates the supply voltage is at the minimum required for correct operation
BATBUS Not used in the mobile configuration
BATMON Indicates the voltage on the main radio supply from external power source
These inputs are used to control the following FPGA outputs:
Output Description
PWRHOLD Set during normal operation, the radio stays on regardless of the on/off switch. When
PWROFF indicates that a switch off is required, software shut down is executed followed
by a release of this output
BATOFF Not used in the mobile configuration
Additionally the /LBOUT interrupt is used to execute a fast shutdown of the software when the supply voltage drops
below that needed for normal operation, or when the power source is removed without switching the radio off.
3.2.4.1 Power Supply Frequency Control
The power supply software controls the switch mode power supply frequency output according to the RF frequency
used. The frequency is checked and changed if necessary at every synthesizer frequency change.
3.2.5 Monitoring
The H8 software monitors the following signals:
Signal Description
Out-of-lock In all active modes, every 100 ms
EPTT/RTS In all modes, every 20 ms
RSSI In receive modes, every 100 ms
WRU In all modes, every second
DC voltage In all modes, every 5 seconds
PA temp In transmit modes, every second
REF temp In all modes, every 5 seconds
PA current In transmit modes, every second
3.2.6 Radio Control Drivers
A number of low-level software drivers are used by H8, which interface to the transceiver hardware.