pub const CTCSS_FREQUENCIES: [f64; 51];Expand description
CTCSS (Continuous Tone-Coded Squelch System) frequency table.
51 entries: 50 sub-audible CTCSS tone frequencies (indices 0-49) plus
the 1750 Hz tone burst at index 50. Indexed by ToneCode. The CTCSS
table is at firmware address 0xC003C694.
The D75 supports indices 0-49 (50 CTCSS tones), extending the D74’s 35-tone table with 15 additional tones including interleaved entries in the 159-200 Hz range (159.8, 165.5, 171.3, 177.3, 183.5, 189.9, 196.6, 199.5) and high-frequency tones (210.7-254.1 Hz).
Index 50 (1750.0 Hz) is the European repeater access tone burst, confirmed by ARFC-D75 decompilation. It is NOT a CTCSS tone — it is a short audio-frequency burst used to open European repeaters.
This table corresponds to KI4LAX TABLE A in the CAT command reference, which maps hex indices 0x00-0x31 to CTCSS tone frequencies. Index 0x32 (50) for the 1750 Hz tone burst is from ARFC-D75 RE.