ZETRON 30 Worldpatch, Instruction Manual, Page: 18 / 60

Section 3. Operation
3-6
state until commanded to switch states. The output state is saved in the unit’s
non-volatile memory and is restored as set even if power is cycled.
Call Alert
When enabled, Call Alert allows the Model 30 to key up during an existing
Mobile-to-Mobile conversation and send two quick beeps over the air when a
telephone call comes in. The mobiles may then elect to stop their conversation so
one of them may answer the call.
Dual Function Connect Button
This is designed for installations where the Model 30 is used on an operator’s
desk to route calls between the office and the field. In normal operation when the
Connect button is pressed while the system is idle, the phone line is placed
directly on the air in conversation mode. Enabling this option instructs the Model
30 to ring out over the air to hail the mobile user when the button is pressed. If
the channel has activity, the phone line will be placed in conversation mode
when the button is pressed.
SIMPLEX OPERATION
Simplex Modes
There are six simplex modes.
Simplex VOX
This is the standard simplex mode that keys the transmitter using phone voice
(VOX) detection. When neither party is talking, the Model 30 watches for either
VOX or carrier detection. When the Model 30 detects VOX, it keys the
transmitter and allows the telephone audio to pass to the transmitter. When VOX
drops and the VOX HOLD timer expires, the transmitter is dropped and the
Model 30 returns to waiting. When the Model 30 detects carrier, it allows mobile
audio to pass to the telephone. When carrier drops, and the COR HOLD timer
expires, the Model 30 returns to waiting.
The digital voice delay option board may be installed to enhance the simplex
VOX mode. Since the Model 30 uses the voice detector to know when to key the
transmitter, the first syllable can be lost while the transmitter comes up. CTCSS
decoders can also contribute to the lost syllables. Adding the digital voice delay
board delays the phone audio so that the transmitter will have plenty of time to
get “on line” before the phone audio is passed to the mobile.
Simplex VOX with Prekey
This mode is identical to the above mode, with one exception. When carrier
drops, it is assumed that the telephone will want to start talking, so the Model 30
“prekeys” the transmitter. This reduces the chance of lost syllables while the
transmitter is coming up to full power. If the phone party does not begin speaking