Remote Control Console
68
9. Sample Setup Procedure
The following example sets up the audio levels on both the transmit and receive sides.
9.1 UIM Transmit Path
:
The transmit path begins at the microphone of your choice and ends with the transmit card of your choice.
9.1.1
Microphone adjustments
There are two microphone inputs to the C-6124. Both inputs are accessible from the back panel of the User
Interface Module. One is a four-wire plug and the other is a six-wire plug. The four-wire plug will accept either a
handset or headset. The six-wire plug will accept either a desk microphone or a gooseneck microphone. Both plugs
may be used at the same time. Keep in mind, though that the six-wire plug has priority. Transmit audio from the six-
wire plug is blocked only when the PTT of the 4 wire plug is active or when a phone conversation is active.
Both the handset/headset and the desk/gooseneck microphone inputs go through dedicated preamplifier
stages and are then summed together before being processed through an Automatic Level Control (ALC) circuit
(commonly known as “compressors”). In tuning the microphone levels the goal is to adjust the preamps so that
nominal voice levels through both microphone (if two are being used simultaneously) are of equal level at the output
of the summing amp. The following cookbook will guide you through the tuning process:
9.1.2
Determining the knee of compression
The system is designed for a .77V maximum on the internal busses. The ALC will limit the output signal to
.77V. This will happen automatically, though. Your task is to tune the microphones so they go into compression
when you want them to. Your desired knee of compression may be nominal voice level. This setup may be
performed simply by making a tone (by human vocal cords) into the microphone at about the level you expect the
operator to be talking at the distance from the microphone that the operator is likely to be. Adjust the microphone
preamp for a predetermined level at the summing amp. The level at the summing amp is not very important. What is
important is that the level be the same at the output of the summing amp for both microphones. At the factory we
choose .08V. The respective preamps will bring nominal voice from the microphones up to .08V and the ALC will
convert the .08V to .77V. In the following examples .08V will be used to give an absolute example.
9.1.3
Adjusting handset/headset microphone levels
Make a vocal tone into the handset while adjusting RV1 on the UIM analog PCB for .08V at TP7. You
should see .08V at TP9, the output of the summing amp. While you are here adjust the sidetone level by adjusting
RV2 until you can comfortably hear yourself in the earpiece. If a handset/headset is part of the system JP3 on the
UIM Analog must be in the A position. Speak into the handset and listen to the earpiece. You should hear a portion
of your voice being routed back to the earpiece. This is known as sidetone. The sidetone level is adjusted by RV2.
9.1.4
Adjusting desk microphone/gooseneck microphone levels
Make a vocal tone into the desk microphone/gooseneck microphone at the distance you expect the operator
to be at. Adjust RV6 on the UIM Analog PCB for .08V at TP18. You should see .08V at TP9, the output of the
summing amp. If there is not a handset/headset in the system be sure that JP3 is in the B position.
9.1.5
Setting the knee of compression
With the nominal voice level coming in through either of the microphone inputs adjust RV15 until you see a
level of .59V at TP10, the ALC output. The ALC will compress signals to .77V (+3db/-1db) over an increase of input
of up to 30db. What this means is that yelling into the microphone will not produce more than 3db above nominal
voice level. It is up to the technician to determine where the “knee” of compression is. Generally, the knee of
compression for the C-6124 ALC starts at .59V and ends at around .77V. The consoles are shipped from the factory
with the assumption that the “knee” is at .59V.
9.2
Alert tone adjustments
The Alert tone button on the touchscreen front panel produces a 1000Hz tone on the transmit audio. If no
cards are in the transmit condition the console will key up the Selected cards and transmit the Alert tone. If the
Selected cards are already in the transmit mode when the Alert button is pressed then the C-6124 will just add 1khz to
the transmit audio path. Note that to produce an Alert tone the ALERT button on the touchscreen must be pressed
to enable the oscillator. There is a way to lock the Alert tone in the enable position. That is to remove the jumper
plug for JP7 on the UIM Analog PCB. This will place a 1000Hz signal on the transmit path until the jumper is restored
to the A position (the B position disables the oscillator).
9.2.1
Alert tone frequency
