Z-Series Audio Optimization Guide
Interoperability Now
Page 7 of 10
Z-Series Audio Optimization Guide
3.2
Transmit (Output) Level – (TX Audio Level)
The
Transmit Output
level should be set to properly modulate the donor radio transmitter. Audio
coming from the donor radio, when doing a normal voice volume radio count, should be heard
in the companion radio at the same level as received conversations from other radios in the system
(as heard in the companion radio).
•
If you have a headset or handset (ACU‑Z1), cross-connect it with the radio interface so
that speaking into the headset/handset causes the donor radio to transmit.
•
If you do not have a headset or handset, you will need to cross-connect another channel
that has its RX audio level properly set up (e.g. a second radio channel or a backhaul
channel).
Note:
Doing the RX audio level adjustment
before
setting the TX audio level (or using a handset
or headset) and verifying it via the front panel LED will help prevent a mutually-erroneous
condition where a too-low RX audio input is compensated by a too-high TX audio input on a
cross-connected channel. This condition is particularly troubling whenever a third interface is
introduced to the system – its incoming audio will be too low for one of the mutually erroneous
interfaces and too high for the other.
3.3
Transmit Delay (TX Audio Delay)
If the donor radio is used with a trunked radio system, it may be necessary to adjust the TX audio
delay. If initial syllables are missing in the received audio of the companion radio (when listening
to transmissions from the Z-Series device/donor radio) increase the TX audio delay of the Z-
Series interface connected to that donor radio.
The test for determining the proper TX Delay is best done when talking into a USB headset (or
handset on the ACU‑Z1) that is cross-connected with the radio interface, rather than some other
interface. The reason is that using the headset or handset precludes any chance that any audio is
missing initial syllables
before
being sent to the donor radio to be transmitted to the trunking
system.
Note that a different audio delay setting, RX Delay (below), must be increased if initial syllables
are clipped on the
incoming
audio of a Radio Channel. If you are using a cross-connected radio
channel instead of a handset or headset for determination of the proper TX Delay setting, and
additional increases in TX Audio Delay have no effect on missed first syllables in the field radio,
then it may instead be necessary to increase the RX Audio Delay in that cross-connected Radio
Channel. It is an uncommon but possible condition.
Explanation for TX Delay:
When a radio user initiates a transmit sequence for a trunked
radio, that user depresses the PTT switch on the radio, which sends a signal to the
system’s trunking controller, asking to be assigned to a free (not currently busy) channel.
The duration of time required for channel acquisition varies according to availability.
Once the trunking controller determines a channel, it sends a signal back to the user’s
radio that automatically sets the radio to a free channel, and it signals this to the radio
user by a tone called a
channel acquisition tone
or simply a
go-ahead tone
. The trunked
system radio user is trained to not begin talking until this tone is heard.
Unfortunately, this tone cannot be heard by users on other systems that are cross-
connected by the Z-Series device to the trunked radio system. If the user is on a non-radio
