(iv)
Valid Tone Period for Successful Decode.
80% deviation and full quieting.
-40% to +70%
(v)
Code Format.
A successful decode will occur if the correct code address is preceded with
and/or
followed by
erroneous tones or noise.
(vi)
Decode Recognition.
Upon receipt of correct decode address, no action occurs (ie mute open, auto
acknowledge, etc) until approximately one tone period has elapsed.
2.4.2
PRM80 CTCSS Specification
2.4.2.1
Encoder
(i)
Tone Deviation.
25kHz channel spacing
500 to 700Hz.
20kHz channel spacing
400 to 560Hz.
12.5kHz channel spacing
250 to 350Hz.
7% to 36% of systems deviation adjustment range.
(ii)
Tone Distortion.
Less than 5.0%.
(iii)
Frequency Accuracy.
+/- 0.30% over -30 degC to +60 degC.
(iv)
Number of Tones.
There are, including disabled, 38 available tones. See Table 2.1.
2.4.2.2
Reverse Tone Burst.
In order to prevent the mute "tail" associated with the de-response time of CTCSS decoders,
the mobile may be equipped with reverse tone burst (RTB). This RTB, occurs at the end of
CTCSS transmission and consists of a period of CTCSS tone of either 180 or -120 degrees
phase difference to that previously sent. The period of this tone is dependent on the tone
frequency, see Table 2.1.
The RTB installation may be either hardware or software.
(i)
Hardware RTB.
RTB phase Shift:
120 d/- 10 degrees, lagging.
RTB duration:
Between 80mSec to 150mSec.
CTCSS tone frequency dependent. See Table 2.1.
RTB Amplitude Variation
+/- 2dB.
(across CTCSS tone set).
Section 2 Page 7
