User's Manual
16
RADAR COMMANDS
*SR COMMAND & THE 50KHZ REFERENCE CLOCK
The *SR command is used to enquire about the radars measured sample rate. This is an additional self-test
feature to confirm correct operation of the radar to specification.
For example
*SR?<CR>
Radar Response
#SR?50002.21<CR>
There is no pass/fail criteria for the host system for this response as the radar periodically performs this test
against pre-set criteria.
The radar uses an analogue to digital converter, ADC, to digitise the received signals. The ADC clock source is
derived from a crystal on the digitiser board. The crystal used has a frequency of 12.0MHz. This clock is divided
down by 240 to give a reference clock frequency of 50.0KHz.
The reference clock is provided on balanced line outputs compatible with RS422 signal levels.
The radar constantly monitors the sampling frequency by comparing how long the radar takes to collect data
samples by using the processors crystal as a reference, which is independent from the ADC clock source.
Measurements are compared approximately every five seconds and if measurements show a large enough
error then the radar will send an error message 06. The last measurement of the ADC clock frequency can be
accessed at any time by using the *SR command.
*IQ PORT COMMAND
This command is used to enquire or set the IQ port configuration as input or output. The IQ port is default
set to an output.
For example
*IQPORT?<cr>
Radar response
#IQPORT?0
The IQ port provides connections that may be used to observe or inject IQ signals for independent test house
measurement performance verification. When the IQ port is configured as an input the radar will disconnect
from the microwave module and connect its baseband circuitry to the IQ port pins. The radar will measure
injected events in the normal way and the radar will mark detected targets with a direction field of X or Y
depending on the direction of the target indicating the test condition.
It should also be noted that the IQ Port can be configured as an input.