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