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Section 1: Coupler Tests of FM Systems
5.
Place the assembly 2 ft (60 cm) from the transmitting microphone, out of the sound
field of the speaker. See Figure 1.4.2.
6.
Stand clear of the test area, holding the remote module. You are now ready to test
the FM transmitter/receiver.
Figure 1.4.2
FM setup system
Isolating the environmental microphone
The testing procedures in this section call for the environmental microphone to be turned on
as well at the FM microphone. In most quiet testing environments, this will call for the FM
setup described in Section 1.4.1. However, if you are testing in a noisy environment, you
may want to isolate the environmental microphone from the room noise.
To check if you need to provide sound isolation for the environmental microphone when
testing the FM microphone in FM+ENV mode, do this procedure:
1.
Set the FM microphone up for testing as described in Section 1.1.3.
2.
Set the FM receiver to receive FM only.
3. Press [START/STOP] on the remote module to start a composite measurement.
When the measurement stabilizes, press [START/STOP] again.
4.
Observe the RMS OUT for this FM-only signal.
5.
Set the FM receiver to receive FM+ENV.
6. Repeat Step 3.
FM transmitter
FM mic
Reference mic
(not used)
Probe mic
FM receiver
attached
