Operation Manual

FT-252 OperaTing Manual50
Busy Channel Lock-Out
(
BCLO
)
The BCLO feature prevents the radio’s transmitter from being activated if a signal
strong enough to break through the “noise” squelch is present. On a frequency where
stations using different CTCSS or DCS codes may be active, BCLO prevents you from
disrupting their communications accidentally (because your radio may be muted by its
own Tone Decoder). The default setting for the BCLO is OFF, and here is how to change
that setting:
1. Press the
[
SET/ATS
]
key to enter the Set mode.
2. Rotate the
DIAL
knob or press the
[
p
]
/
[
q
]
key to select
Set Mode Item 6:
BCLO
.
3. Press the
[
SET/ATS
]
key momentarily to enable adjust-
ment of this Set Mode Item.
4. Rotate the
DIAL
knob or press the
[
p
]
/
[
q
]
key to set this Set Mode Item to “
BCL.
ON
” (thus activating the BCLO feature).
5. When you have made your selection, press the
PTT
switch to save the new setting
and exit to normal operation.
DCS Code Inversion
The DCS system was rst introduced in the commercial LMR (Land Mobile Radio)
service, where it is now in widespread use. DCS is sometime referred to by its different
proprietary names, such as DPL
®
(Digital Private Line
®
, a registered trademark of Mo-
torola, Inc.).
DCS uses a codeword consisting of a 23-bit frame, transmitted (subaudible) at a data
rate of 134.4 bps (bit/sec). Occasionally, signal inversion can result in the complement
of a code to be sent or received. This prevents the receiver’s squelch from opening with
DCS enabled, as the decoded bit sequence would not match that selected for operation.
Typical situations that might cause inversion to occur are:

Connection of an external receiver preamplier.

Operating through a repeater.

Connection of an external linear amplier.
Note that code inversion does not mean that any of the above listed equipment is defec-
tive!
In certain amplier congurations, the output signal (phase) is inverted from the input.
Small signal or power ampliers having an odd number (1, 3, 5, etc.) of amplication
stages may result in inversion of a transmitted or received DCS code.
While under most circumstances this should not occur (amplier designs and industry
Miscellaneous Settings
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