ACCEPTANCE TESTING
6-15
Internal AM depth and distortion
Specification
Range:
0 to 99% in 0.1% steps.
Accuracy:
For carrier frequencies up to 1 GHz,
±
4% of setting
±
1% depth.
Usable to1.35 GHz (2050T), 2.7 GHz (2051T), 5.4 GHz (2052T).
Envelope distortion:
Less than 3% THD for AM depths up to 80% at 1 kHz modulation
frequency.
Less than 1% THD for AM depths up to 30% at 1 kHz modulation
frequency.
Phase mod on AM:
Typically less than 0.1 rad at 30% depth on a 500 MHz carrier.
Test equipment
Description Minimum
specification Example
Modulation meter
1.5 MHz to 1 GHz.
Aeroflex 2305
+ distortion option
Accuracy: Better than 1.1%.
Test procedures
C0332
RF
OUTPUT
UUT
Modulation Meter
RF
INPUT
➤
Fig. 6-9 Internal AM depth and distortion test set-up
(1) Connect the test equipment as shown in Fig. 6-9.
(2) Set the UUT to
[RF Level]
0 dBm
[Carrier Freq.]
1.5 MHz
[AM]
30%.
(3) Measure the AM depth and the envelope distortion on the modulation meter using the 50 Hz
to 15 kHz filter setting at the frequencies shown in Table 6-10. Check that the measured AM
depth and distortion are within specification.
(4) Set the UUT to an AM depth of 80% and repeat (3) above.
(5) Set the UUT to
[RF Level]
+7 dBm (+4 dBm for instruments fitted with Option 012) and
repeat (3) and (4) above.
Table 6-10 AM depth and distortion frequencies
Carrier frequencies (MHz)
1.5
400
31.0
500
43.0
850
200.0 1000