NAC to CTCSS
Here's something I found on the subject...
From the TG-001 P25 Radio Systems Training Guide
Daniels Electronics - Home Page
Chapter 3: P25 Practical Applications 27
CTCSS to NAC Conversion
Early TIA documents specifi ed a formula for converting analog CTCSS tones and DCS codes to specific NAC codes. Those documents have since been removed and the selection of NAC codes has been left
to the user. Some government agencies have defi ned a conversion table for their own use for translating CTCSS to NAC codes (eg. State of California and others).
Shown below is the early TIA conversion table from CTCSS to NAC codes. These codes were determined by taking the CTCSS frequency and multiplying it by ten, then converting the integer result
to a hexadecimal number.
CTCSS to NAC code conversion chart
CTCSS NAC Code
67.0 Hz $29E
69.3 Hz $2B5
71.9 Hz $2CF
74.4 Hz $2E8
77.0 Hz $302
79.7 Hz $31D
82.5 Hz $339
85.4 Hz $356
88.5 Hz $375
91.5 Hz $393
94.8 Hz $3B4
97.4 Hz $3CE
100.0 Hz $3E8
103.5 Hz $40B
107.2 Hz $430
110.9 Hz $455
114.8 Hz $47C
118.8 Hz $4A4
123.0 Hz $4CE
127.3 Hz $4F9
131.8 Hz $526
CTCSS NAC Code
136.5 Hz $555
141.3 Hz $585
146.2 Hz $5B6
151.4 Hz $5EA
156.7 Hz $61F
162.2 Hz $656
167.9 Hz $68F
173.8 Hz $6CA
179.9 Hz $707
186.2 Hz $746
192.8 Hz $788
203.5 Hz $7F3
206.5 Hz $811
210.7 Hz $83B
218.1 Hz $885
225.7 Hz $8D1
229.1 Hz $8F3
233.6 Hz $920
241.8 Hz $972
250.3 Hz $9C7