Radioddity GD-88 - Bandwidth; CTCSS sub audio and DCS signaling

Radioddity Extended manual for Radioddity DB25-D, DB40-D & GD-88 v3.0
© Radioddity 2023 page 190 of 252
13.27 Bandwidth
For each channel it is possible to specify the working bandwidth for TX and RX
frequency. Narrow band has a bandwidth of 12.5 kHz whereas Wide band has a
bandwidth of 25 kHz. In digital mode, the channel bandwidth is set for 12.5 kHz
regardless of what´s displayed and cannot be changed or adjusted.
13.28 CTCSS sub audio and DCS signaling
For analog channels the Radioddity DB25-D, DB40-D and GD-88 support a total of
51 CTCSS (Continuous Tone Coded Sub audio Squelch) frequencies and 103
normal DCS codes and additional 103 inverted DCS codes. CTCSS is often also
called PL tone (PL® for Private Line, a trademark of Motorola) or just tone squelch.
A DCS (Digital-Coded Squelch) - often also called DPL (Digital Private Line) -code in
fact is a 134.4 bps (sub-audible) bitstream of 12 data bits followed by 11 check
bits. This allows to detect and correct up to 3 buggy bits. The last 3 data bits are a
fixed '001', this leaves 9 code bits (512 possibilities). Those are represented as 3-
digit octal numbers. The Telecommunications Industry Association (TIA) has
standardized 83 DCS codes.
13.28.1 Supported CTCSS frequencies
62,5
67,0
69,3
71,9
74,4
77,0
79,7
82,5
85,4
88,5
91,5
94,8
97,4
100,0
103,5
107,2
110,9
114,8
118,8
123,0
127,3
131,8
136,5
141,3
146,2
151,4
156,7
159,8
162,2
165,5
167,9
171,3
173,8
177,3
179,9
183,5
186,2
189,9
192,8
196,6
199,5
203,5
206,5
210,7
218,1
225,7
229,1
233,6
241,8
250,3
254,1
All figures in Hz