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21-9.4 Calibration Test Pattern
The Audio Zone provides for selection of a
Calibration Test Pattern when the GENERATE
mode is selected in the RF Zone. This pattern is the
same as the 1011 Hz Tone Test pattern with every
th
20
bit inverted, to yield 172 errors out of 3456
bits. When this pattern is compared with a 1011 Hz
tone test pattern, a 4.977% BER will result. This
pattern conforms to the calibration test pattern
specified in the Digital C4FM/CQPSK Transceiver
Measurement Methods Document TIA/EIA IS-
102.CAAA for the Project 25 system.
21-9.4.1 Generate Mode
The analyzer generates a Calibration Test Pattern
when Generate mode is selected in the RF Zone
and the Calibration Test Pattern is selected for the
"Code:" field in the Audio Zone.
When code Calibration Test Pattern is selected in
the Audio Zone (Figure 21-16), the analyzer
modulates the Calibration Test Pattern on the
carrier at either of two output ports:
RF I/O port, or
GEN OUT port.
Both deviation level control and a deviation switch
are provided in the Audio Zone for deviation
control of the generated signal.
The deviation level "PRJ25 Dev:" can be set by
either the keypad or the TUNING knob to enter
the desired deviation. The deviation range varies
depending on whether the bandwidth (in the RF
Zone) is set to narrow or wide.
BW Setting
Deviation Range
Narrow
0.50 to 5.00 kHz maximum, in
0.05 kHz increments
05.0 to 50.0 kHz maximum, in
Wide
0.50 kHz increments
The deviation switch with values of Off and
Continuous is located to the right of the deviation
level control field. Move the cursor to the switch
field and turn deviation on "~" or off "X" using the
softkeys.
The generated Calibration Test Pattern can be used
to determine if the unit under test receiver is
operating correctly. This is done by computing the
BER for the received calibration test pattern when
compared against a 1011 Hz tone test pattern in the
unit under test. If the Calibration Test Pattern is
received correctly, the measured BER will be
4.977%. These measurements will only be possible
for radios that are capable of computing a BER
when the received signal is compared with a stored
1011 Hz Tone Test pattern and having the
necessary radio test mode software.
21-9.5 Silence Pattern
The Audio Zone provides for selection of a Silence
Pattern when the GENERATE mode is selected in
the RF Zone. This pattern will produce silence in
the radio under test.
21-9.5.1 Generate Mode
The analyzer generates a Silence Pattern when
Generate mode is selected in the RF Zone and the
Silence Pattern is selected for the "Code:" field in
the Audio Zone.
When code Silence Pattern is selected in the Audio
Zone (Figure 21-15), the analyzer modulates to
Silence Pattern on the carrier at either of two output
ports:
RF I/O port, or
GEN OUT port.
Both deviation level control and a deviation switch
are provided in the Audio Zone for deviation
control of the generated signal.
The deviation level "PRJ25 Dev:" can be set by
either the keypad or the TUNING knob to enter the
desired deviation.
depending on whether the bandwidth (in the RF
Zone) is set to narrow or wide.
BW Setting
Deviation Range
Narrow
0.50 to 5.00 kHz maximum, in 0.05
kHz increments
05.0 to 50.0 kHz maximum, in 0.50
Wide
kHz increments
274
The deviation range varies
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