M8SL2-00-002-812 T855 Initial Tuning and Adjustment B3.9
© Copyright Tait Electronics Limited August 2004. All rights reserved.
3.5.2 Audio Processor Linking Details For CTCSS
You must connect the audio processor links correctly according to the CTCSS option
used, as shown in the table below.
The conditions stated in the above table are defined as follows:
• standard, no CTCSS – no CTCSS or other sub-audio signalling used
– audio bandwidth 300Hz to 3kHz
– hum and noise –55dB
• received CTCSS tone – tone and speech transmitted down 600Ω line
+ speech to line output – audio bandwidth 10Hz to 3kHz
– hum and noise –45dB
• high pass filtered speech – 400Hz to 3kHz
+ internal CTCSS detection – hum and noise –30dB with 250.3Hz tone present
• external CTCSS detection – decoding performed through the receiver (but
externally)
– speech injected back into receiver via “AUDIO-2"
and sent down 600Ω line
Note 1: AUDIO-2 is available on D-range 1 (PL100) pin 7 via the link resistor R160.
Although PL100 pin 7 is already assigned to SERIAL-COM, this can be disa-
bled by removing R808.
Note 2: External CTCSS units can connect in series with the audio chain via
AUDIO-1 and AUDIO-2.
CTCSS Option PL230 PL240
standard, no CTCSS 2 – 3N – P2 – 3H – J
received CTCSS + speech
passed to line output
3 – 4P – Q1 – 2G – H
high pass filtered speech,
internal CTCSS detection
2 – 3N – P4 – 5K – L
external CTCSS detection 1 – 2M – N4 – 5K – L
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