His DTMF decoder box uses a CM8870 DTMF decoder chip, ... so in theory software tone decoder could be written making the process only a single piece of hardware.

Though many of us will never have experimented with it, most readers should be familiar with DTMF as the tones used by the telephone system for dialling. If your youth was not misspent mashing 4-4-… ...

The HT9170 decodes the 16 DTMF tone pairs into a 4-bit BCD code output. The 74AHC04D, a high-speed Si-gate CMOS Hex Inverter, is used as a “not” gate for the circuit, the HEF4030BT Quad 2-input ...

Winston-Salem, NC&#8212CML Microcircuits' CMX867A, a V.22 multi-standard modem IC for telephone-based information systems, includes an enhanced DTMF decoder, thus affording a more compact design and ...