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Testing FM Systems with FONIX 6500-CX Analyzers
7.
Observe the RMS OUT for the FM+ENV setting. If the RMS OUT is more than 3 dB
higher for FM+ENV than for FM-only, then you will need to isolate the environmen-
tal microphone when testing the FM microphone in FM+ENV mode. If the RMS
OUT for both signals is within 3 dB, no additional setup is necessary.
8.
To isolate the environmental microphone, it is preferable to use a spare sound cham-
ber if one is available to you. Otherwise, take a shoebox, line it with packing foam,
and place the environmental microphone inside, covering it with some more foam.
See Figure 1.1.3B. This should isolate the room noise from the environmental micro-
phone.
1.4.3 Environmental microphones on body-worn receivers
1.
Enter Real Ear Mode by pressing [START/STOP] on the remote module or [PROBE]
on the 6500-CX main module.
2. Affix the FM receiver to the platform stand in the manner shown in Figure 1.4.3A.
Figure 1.4.3A
Attaching reference microphone
3.
Using Fun-Tak, affix the reference microphone to the receiving unit so the entrance
to the reference microphone is very close to that of the environmental microphone.
4.
Place the FM receiver six inches (15 cm) from, and facing, the loudspeaker (Refer to
Figure 1.4.3B) and set it to receive input from the environmental microphone only.
5. Choose a place to stand during testing, preferably away from the loudspeaker and
microphone, holding the remote module. Stand precisely in this place during both
leveling and testing.
6.
Press [LEVEL] on the remote module. This levels the test signal at the place where
the FM receiver microphone will be during testing.
7.
Leave the reference microphone in place during testing.
Reference
Microphone
