IC-R15 Tone Squelch, DTCS & Duplex

Summary: How to use the IC-R15’s tone squelch and DTCS squelch, and how to listen to the input side of a duplex channel.

Tone Squelch and DTCS

In FM and FM-N the tone squelch opens only when the received signal carries a matching subaudible tone or DTCS code. A reversed tone squelch is also available, which mutes the squelch when a matching tone or code is present.

1. In VFO mode push [QUICK] and choose TONE.
2. Choose the tone squelch type.
3. Rotate [DIAL] to choose a tone frequency or DTCS code and push [ENT]. For DTCS you can choose Normal or Reverse polarity by moving the cursor and rotating [DIAL].

Tone frequencies (Hz): 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.

DTCS codes: 023, 025, 026, 031, 032, 036, 043, 047, 051, 053, 054, 065, 071, 072, 073, 074, 114, 115, 116, 122, 125, 131, 132, 134, 143, 145, 152, 155, 156, 162, 165, 172, 174, 205, 212, 223, 225, 226, 243, 244, 245, 246, 251, 252, 255, 261, 263, 265, 266, 271, 274, 306, 311, 315, 325, 331, 332, 343, 346, 351, 356, 364, 365, 371, 411, 412, 413, 423, 431, 432, 445, 446, 452, 454, 455, 462, 464, 465, 466, 503, 506, 516, 523, 526, 532, 546, 565, 606, 612, 624, 627, 631, 632, 654, 662, 664, 703, 712, 723, 731, 732, 734, 743, 754.

A tone scan can search for an unknown tone or code; see IC-R15 Scanning: VFO, Memory & Tone Scans. If nothing is heard, check that the tone squelch isn’t left on (see IC-R15 Troubleshooting & Resetting).

Duplex Operation

Some services transmit on one frequency and receive on another (repeaters, and marine shore stations for example). The IC-R15 receives, but it can shift its receive frequency by an offset while you hold [SQL] so you can hear the other side.

1. Push [QUICK] and choose DUP.
2. Choose OFF (simplex), DUP- (shifts down while monitoring) or DUP+ (shifts up).
3. Rotate [DIAL] to set the offset (0.00 to 159.99 MHz; the VFO tuning step is used) and push [ENT]. “D-” or “D+” shows.
4. Hold [SQL]: the receive frequency shifts while it’s held.

The 430 MHz band’s default offset is 5.000 MHz. The guide’s example uses marine VHF, where a base station transmits on 160.850 MHz and the ship station on 156.250 MHz, a 4.6 MHz offset. During a memory scan the offset frequency is also scanned if DUP Check During MR Scan is on.