Decodes all DTMF digits
The TM-16A Plus detects and displays all 16 DTMF (Dual Tone Multi Frequency) digits: 0-9, #, *, A, B, C, and D. (The A, B, C, and D digits are generated by some communications radios, and by other equipment.) Digits are displayed 16 at a time from an 80 digit memory using scroll left and scroll right push-buttons. The clear button clears the display and display memory, and resets the device. The TM-16A Plus includes an RS-232 serial output data port that will output DTMF data in ASCII format at 9600 baud.

Audio Sources & Cables
The TM-16A Plus decodes DTMF from sources with audio levels between .1 Vpp and 6 Vpp. Three cables are included with the product. The RJ-11 to RJ-11 patch cord connects the unit directly to telephone equipment. Other common connections are made by 3.5mm plug audio patch cord to the external speaker jack or earphone jack of equipment such as a scanner or tape recorder. The included 3.5mm plug to alligator clips cable may be used to clip on to telephone terminal blocks or speaker outputs.

The low-power CMOS LCD display, built-in 9 volt alkaline battery compartment (battery is included), and rugged metal case combine to make the TM-16A a quality, portable piece of test equipment. With the (included) external AC power adaptor attached, the 9 volt battery is automatically disconnected, conserving battery power.

Built-In Monitor
The Audio signal is output to a built-in amplifier and speaker for monitoring the audio source. The Volume Level potentiometer is settable through a small hole in the enclosure. On Hook, Off Hook, Flash Hook Off hook condition is detected and displayed as ”. Hook-Flash time is captured and displayed in milli-seconds preceded by ‘F’, and followed by ‘ms’.

Rotary Dial Digits
The unit also decodes and displays standard telephone rotary dial pulses representing digits 0-9. Digits are displayed preceded by ‘P’ indicating pulse dialing. (DTMF digits are preceded by ‘T’ indicating tone dialing).

Direct Connection
Telephone equipment generates signalling for on/off/flash hook and for rotary pulse dialing by breaking the current flow through the tip and ring phone wires. Consequently the TM-16A needs to be directly connected to this (telephone) equipment to use these features.

Decoding From Tape Recordings
The TM-16A can decode DTMF from tape recordings, provided the recording is of good quality. If you intend to use a tape recording, we recommend you use the same recorder for both record and playback operations. A direct electrical connection to your audio source is required, audio recorded “through the air” using a microphone may be too distorted to decode DTMF. Also, recorders modified for super long play on cassette tapes generally do not produce the audio quality required for successful DTMF decoding.

Display Formatting
Approximately five seconds following a sequence of digits, a “-” (hyphen) will be inserted in the display to separate the number groups, and make the information easier to view. All displayed characters, except the hyphen, are immediately transmitted on the serial port of the TM-16a Plus.

RS-232 Output Formatting
The serial output of the TM-16a Plus can be connected to either a computer or a serial printer. A carriage return/line feed is sent when “On Hook” is detected, as well as when a hyphen is displayed. Connected to a serial printer, the user can have immediate access to a hard copy of the decoded information, without dedicating a computer to the task. A terminal program will display the same information.

The TM-16A typically draws 20 ma either from its built-in 9 Volt alkaline battery (included) or from a 12 Volt DC power supply (included). The unit’s metal enclosure measures 6.00″ wide by 2.75″ deep by 1.10″ high. The TM-16A Plus comes complete with three audio cables, a 9 Volt alkaline battery, and an operations manual. Both units feature an internal jumper for selecting normal (12.5 digits per second) or high speed (25 dps) DTMF decoding speed. The TM-16A Plus also includes a RS-232 data output port.