Tektronix CMD 80, Руководство пользователя

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Analog: Manual Test (Signaling)
3–80
CMD 80 Digital Radiocommunication Tester User Manual
This test ensures that the volume level of any frequency transmitted by the base
station and received by the mobile station falls within a predefined window.
NOTE . You must turn off the mobile station’s expandor when performing this test.
The tester measures the audio frequency response as the ratio of the electrical
audio output of the mobile receiver to the modulated signal output of the base
station (tester) as a function of frequency. See Figure 3–55.
NOTE
. The tester uses internal filters in determining the results in the AUDIO
FREQUENCY RESPONSE menu. Refer to Appendix B for filter descriptions
and their use.
Figure 3–55: Analog receiver quality — audio freq response (normal mode) menu
NOTE . When performing the receiver audio frequency response test, the tester
compensates for the mobile station’s de-emphasis filter.
When you press the AUDIO FREQ RESPONSE softkey, the tester displays the
audio frequency response curve plotted between the upper and lower limit lines.
Frequencies of the response curve that are not within the limit lines are indicated
in inverse video at the bottom of the display.
The 0 dBm reference point amplitude is determined by the value you set with the
MOD PEAK DEVIATION softkey. You can use the AUDIO FREQUENCY
RESPONSE configuration menu to set the 0 dBm reference frequency with the
MODULATION FREQUENCY softkey. You can also use the configuration
menu to set the upper limit line, lower limit line, and the number of points
sampled. Refer to AUDIO FREQ RESPONSE on page 3–127.