Kenwood TKR-750 Service Manual page 9

Current : When any PTT as described above is active
while the repeater is in use or the duplex-base station is re-
ceiving, the "paired" encode QT/DQT associated with re-
ceiving QT/DQT is transmitted. When any PTT is active
while the repeater or the duplex-base station is in idle pe-
riod, the "Primary" encode QT/DQT is transmitted.
Primary : When any PTT (provided that the Priority of any
PTT is higher than the Priority of Repeat PTT) is active while
the repeater is in use, the encode QT/DQT changes
"paired" encode QT/DQT to "Primary" while continuing to
transmit. When any PTT is active while the repeater is in
idle period, the "Primary" encode QT/DQT is transmitted.
In the base station, the "Primary" encode QT/DQT is always
transmitted regardless of the receiver status.
7-3. QT Reverse Burst Time
During repeat with QT tones, the repeater re-transmits a
phase-shifted burst of the QT tone ("reverse burst") when it
detects the radio using the repeater has un-keyed and also
sent a reverse QT burst (squelch-tail elimination). This
mutes a receiving radio's speaker audio before its receiver
circuit shuts off causing squelch tail noise in the speaker
audio. The TKR-750 can select the time between 140 to 200
ms that the QT reverse burst is sent. Typically this time
should not have to be adjusted from the default value. The
transmission of the QT reverse burst can be also inhibited if
the QT Reverse Burst function is set to "No".
7-4. DQT Turn Off Code Time
During repeat with DQT tones, the repeater re-transmits
a specific turn-off code when it detects the radio using the
repeater has un-keyed and also sent the turn-off code
(squelch-tail elimination). This mutes a receiving radio's
speaker audio before its receiver circuit shuts off causing
squelch tail noise in the speaker audio.
The TKR-750 can select the time between 140 to 200ms
that the DQT turn-off code is sent. Typically this time should
not have to be adjusted from the default value.
7-5. Off Hook Decode
The TKR-750 is able to decode QT/DQT regardless
whether the local microphone is in the on- or off-hook condi-
tion. When the Off Hook Decode function is enabled, the
TKR-750 is capable of QT/DQT decode even though the mi-
crophone is in the off-hook condition (or a local microphone
is not installed).
8. Scan Feature
8-1. Scan Operation
Providing that the TKR-750 contains two or more non-pri-
ority ADD channel or one or more non-priority ADD channel
and Priority channel, it starts scanning once the Scan On
function is executed and displays "SC" on the 7-seg LED.
Scanning stops temporarily if any following conditions be
come valid.
OPERATING FEATURES
1) if a RF carrier and a valid QT/DQT is present. The receiv-
2) if a RF carrier is present, providing that the Monitor On
3) if the Squelch Off function is executed. Scanning stops
4) if a local microphone's hook is in off hook status, provid-
resumes after the period set in Dropout Delay Time function
has expired. When the Scan Off function is executed, the
TKR-750 inhibits scanning and displays the selected chan-
nel.
8-2. Scan Sequence
1) Normal Scan : When no Priority channel is set, scanning
2) Single Priority Scan : The Priority channel is set as either
8-3. Revert Channel
during scanning. The time from the end of transmission on
Revert channel to the time scanning automatically resumes
is set in Dwell Time function. The Revert channel types are
Last Called, Last Used, Selected, Selected + TalkBack, Pri-
ority, and Priority + TalkBack.
1) Last Called : The TKR-750 reverts to the channel upon
2) Last Used (with TalkBack) : The TKR-750 reverts to the
3) Selected : The transceiver reverts to the channel set by
4) Selected+TalkBack : The TKR-750 reverts to the channel
5) Priority : The TKR-750 always reverts to the Priority chan-
ing channel number is displayed and the received audio is
heard from a speaker.
function is executed.
on the channel being scanned when Squelch Off is ex-
ecuted, the channel number is displayed and the re-
ceived audio is heard from a speaker.
ing that the Off Hook Scan function is set to Disable.
Scanning stops on the Revert channel, but the audio is
not heard until a valid signal is received.
When the received call is ended, scanning automatically
of ADD channels is done in ascending order.
a fixed channel or a selected channel. When Priority
channel is set, Priority channel and non Priority channel
are scanned by turns. When scanning stops on the non
Priority channel, calls from the Priority channel are still
checked at set intervals while scanning is stopped. This
operation is called Look Back and the interval period is
selected by the Look Back Time function.
The Revert channel is a channel that is used to transmit
which a call was last received even if scanning has re-
sumed (power on default = selected channel).
channel that was last transmitted on (power on default =
selected channel). However, if a call is received on a
channel other than the last transmit channel and PTT is
pressed before scanning resumes, the transceiver "talks
back" on the current receive channel.
the function prior to scan initiation.
set by the Channel 'X' functions or Channel Select func-
tion prior to scan initiation. However, if a call is received
on a channel other than the selected channel and PTT is
pressed before scanning resumes, the transceiver "talks
back" on the current receive channel.
nel.
TKR-750
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