Ceyear 3943B, Руководство по эксплуатации

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8 Technical indicators and testing methods
8.5 Performance characteristics test
111
The test results recorded in the auxiliary table B.8 are recorded in the functional performance test record
table A.1 as a summary of FM demodulation sensitivity for the corresponding band.
8.5.1.9 Third-order intercept points
a) Description of the test items
The third-order intercept point (IP3) is a measure of the ability of the device under test to suppress
intermodulation interference signals generated at the receiving front-end at frequencies 2f
1
-f
2
and 2f
2
-f
1
by two strong input signals with frequencies f
1
=f+∆f and f2=f
2
=f+2∆f, expressed as IP
3
=P
in
+α⁄2, where ∆f
is the frequency interval of the two input signals; IP
3
is the third-order intercept point value, expressed in
dBm as a unit; P
in
is the input signal level of the device to be measured, expressed in dBm;
α is the
difference between the input signal level of the device to be measured and the level of the third-order
intermodulation product, that is, α=P
in
-P
t
, expressed in dB, where P
t
is the level of the third-order
intermodulation product, expressed in dBm as a unit.
b) Test diagram and test instruments and equipment
Synthetic Signal Generator1..................................... Recommend 1464/E8257D
Synthetic Signal Generator2..................................... Recommend 1464/E8257D
Directional Coupler .......................................... Recommended AV70604
Directional Coupler .......................................... Recommended AV70607
1.6GHz low-pass filter
2.9GHz low-pass filter
4.1GHz low-pass filter
6.8GHz low-pass filter
Fig. 8.9 Schematic diagram of the third-order intercept point test
c) Test procedure
1) Connect the test equipment as shown in Figure 8.9.
2) Reset the device to be tested. Set the device to be tested as fixed frequency reception mode (FFM),
and set the frequency reference as the reference. Set the center frequency and attenuator status
according to auxiliary table B.9. Set the frequency width 2MHz and set the level unit dBm. Set the
highest level displayed in the IF panorama window according to the output power of the synthesized
signal generator in auxiliary table B.9, so that the highest level is greater than the value by more than