Sigtronics Dual-CFR - Manual (Page 12)

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Intercom operation and adjustment can be performed by
the following procedure:
1. Turn the intercom SQUELCH control to the maximum
clockwise position. For best system performance set the
intercom VOLUME control as low as possible. On most
systems this will be approximately the 10 o’clock posi-
tion. NOTE: the intercom volume control only adjusts the
volume of conversation between the headsets inside the
vehicle. It does not affect the level at which you hear the
dispatch radio. (see Radio Operation below) You should
now hear yourself and others on the intercom.
2. To adjust the Intercom SQUELCH for voice activated oper-
ation (VOX), it is helpful to have some background noise
(truck engine or ...). Turn intercom SQUELCH control all the
way counter-clockwise. Now, without speaking, rotate the
SQUELCH control clockwise until you hear the background
noise in your headset. Next, rotate it counter-clockwise in
small amounts until the background noise disappears.
Finally, make small adjustments until your voice triggers
the unit at comfortable speaking levels. This procedure
is necessary because the squelch is a “Fast-on, Slow-off”
system.
When you speak, your voice will be heard in the headsets
but the sound will cut off about a second after you stop
speaking. Minor readjustment of the squelch may be nec-
essary if the background noise level changes significantly
(engine idling to cruise power with siren on).
Radio Operation
With the UltraSound System, your radios are heard through
the headsets. Adjust the volume level of the dispatch radios in
the headsets with the volume control on the radios as normal.
NOTE that the radio volume does not effect the intercom
volume and visa versa.
For a typical UltraSound CFR installation, transmitting (talk-
ing to dispatch or tower ground control) from the selected
headset positions is possible on a one-at-a-time basis. The
Driver or Officer positions can transmit at any time simply
by pressing their PTT switches. The other positions cannot
transmit on the radios. When one position transmits, several
things take place automatically:
— All headset microphones, except for the transmitting
position, are muted.
— The selected radio is put into transmit mode.
— The headset microphone audio (your voice) is sent to
the selected radio.
— Sidetone is generated and sent to your headphones.*
* Sidetone is a portion of the transmitted voice signal sent
back into your headset so that you can hear what you are
saying while transmitting. The intercom VOLUME control
adjusts the volume level of the sidetone that you hear in
your headset. The other headsets will also hear the transmis-
sion sidetone. Of course, when the PTT switch is released,
(stop transmitting) all functions return to normal, instantly
and automatically.
Dual-CFR Operation
With the Dual-CFR system, two sets of transmit positions are
available (four transmit positions total). A Driver / Crew #1 set
and an Officer / Crew #2 set. The one-at-a-time transmitting
procedure of the CFR system applies to each set. The Driver /
Crew #1 pair can not transmit simultaneously and the Officer
/ Crew #2 pair can not transmit simultaneously. For example,
the Driver or Crew #1 may be talking to ground control on
one radio while the Officer or Crew #2 is talking to fire dis-
patch on the other radio. All headset positions will hear both
conversations (transmit and receive audio).
UltraSound CFR Specifications
Input Voltage: 11 - 16 VDC
Nominal Current: 0.06 Amps
Maximum Current: 0.10 Amps
Intercom Unit Size: 1-3/4 “ H x 6 - 1/8” W x 4” D
(Mounting bracket & knobs add 9/16” to H & 1 - 3/4” to W)
Weight: 15 oz. (not including cables and hardware)
Warranty: Two Years
Sigtronics Installation Hot Line Number:
1-800-367-0977 ext. 8
Monday through Friday, 8: 00 a.m. to 4:30 p.m.
Pacific Time
www.sigtronics.com
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9-16-2009 Ultrasound_CFR.pdf