Instruction manual

ACU-1000 Operations Manual
4-10 Interoperability Now
In the simple cross-connection depicted in Figure 4-5 the various volume levels to contend with
are:
• How loud the person using Portable Radio A is talking
• The modulation limiting level of the Portable Radio A transmitter
• The RX audio output level of System Radio A (less problematic if a line level out is
used; more so if the level is controlled by the speaker volume knob)
• DSP-2 Module A’s RX audio level setting
• DSP-2 Module B’s TX audio level setting
• The modulation limiting level of the System Radio B transmitter
• Portable Radio B’s volume control
The above list is just for when the user of portable radio A is doing the talking. When the user
of portable radio B replies, a second set of volume levels comes into play.
This procedure will focus on what is under the control of the ACU-1000 operator: the RX and
TX audio levels of the DSP modules, and secondarily, the RX audio output level of the system
radios.
For the cross-connect audio levels to be optimal, the internal audio levels on the audio busses
are maintained at 0 dBm for both input and output. In general, each of the different types of
modules has the means to adjust its respective input or output so that the module is interfacing
the audio bus at a constant level of 0 dBm. For incoming, external audio, the SIGNAL LED on
the front panel is the best indicator of the proper level for optimal performance. For outgoing
transmit audio, the ACU-1000 operator only has control of the signal level presented to the
transmitter and usually does not have the ability to make technical adjustments to the
modulation controls.
Set RX Level Procedure
The RX (Receive) level must be optimized to allow best system operation. First of all,
conversations, especially conference calls, will be more intelligible if all voices are at the same
volume level. Second, VOX and VMR work best at the proper RX level.
• Cross-connect the HSP module to the DSP module being adjusted.
• Monitor the front panel of the DSP module while the radio is receiving a voice signal at
a normal speaking volume level. Listen to the RX audio of the interfaced radio using
the HSP handset.
• Watch the DSP front panel SIGNAL light. It should flicker with the incoming speech.
If the level is too high, the LED will be on constantly during received speech. If too
low, the LED will never come on, or will flicker only occasionally.
• Adjust the RX Level until the Signal LED flickers with incoming speech.