M850-00
T855 Link Selectable Features
G1.1
Copyright TEL 31/09/98
1 T855 Link Selectable Features
1.1 Flat Or De-emphasised Response
The links of PL210 and PL220 may be set to give either a flat or de-emphasised audio
frequency response (refer to Section 1.7 for further details).
1.2 Mute Relay Control
A relay with undedicated contacts (RL210) is available in the audio processor circuit
block for various switching applications. A link (PL270) is available for control of the
relay from the mute circuit (refer to Section 1.7). This makes the relay suitable for con-
trolling the keying of a transmitter in repeater applications.
1.3 Mute Selection
Link PL250 may be set to operate with noise mute or carrier mute (refer to Section 1.7).
1.4 Receiver Disable
The receiver audio can be disabled by pulling the RX-DISABLE line low. When the cir-
cuit is pulled from low to high, the receiver audio cannot be re-enabled until the disable
timer completes its operation. This time is variable from 15ms to 200ms by adjusting
RV220 in the audio processor section.
If required, the operation of this circuit can be disabled by changing the link of PL260
from 1-2 to 2-3.
Typical applications of the receiver disable are as an extra mute for signalling purposes,
or when the T855 is configured as a line controlled base station (refer to Section 4).
1.5 CTCSS Configuration
Links PL230 & PL240 select various CTCSS options (refer to Section 1.7.2).
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