Filser Electronic GmbH
Gewerbestraße 2
86875 Waal
Page 8
2.6 Intercom mode
With Intercom two crew members can talk to each other over the ATR 57
system. This of communication takes place only internally, there is no
transmission.
A special feature is the VOX (Voice Operated Transmission(x)). The
Intercom is opened only if one of the crew members is speaking. This
avoids having all the time surrounding noise on the headphone. The
opening level for the VOX is adjusted as described in para. 3.4.(VOX
level control for intercom).
Only if the transmission key (PTT) is pressed, the radio will change to the
transmission mode. For best results microphones which produce almost the
same output level should be used. The use of very different microphones
can lead to the fact, that the member with the lower output level can not
open the VOX.
The best solution are identical amplified electret-microphones.
The optional Intercom for operation without VOX switch must be mounted
externally. If it is not used the corresponding wire must be connected
(switched) to GND.
2.7 Antenna Installation
The ATR 57 works well with a normal 50Ω-COM-antenna. Polarisation
must be vertical. Using a broad band COM-antenna provides a high
efficiency over the entire COM band. The antenna should installed
according to the manufacturers advises.
Some important general advises for antenna installation are listed below:
ØUnsymmetrical antennas ( λ/4-Antenna) should be mounted on plane
metal surfaces or metal plates of at least 60 x 60cm or more.
ØThe antenna should have the maximal possible distance to motor and
propeller. This avoids getting modulation on your signal.
ØThe COM-antenna should have the maximal possible distance to the
NAV-antenna in order to avoid interference.
