The 'PicDTMF' device connects to a small radio transciever and responds to commands recieved in DTMF format.
The first use is to produce a continous tone for RDF tracking. Being a radio transmitter, It needs to identify itself periodicly. the chose method is morse code. The ability to dynamically select when the tracking tones and ID codes are transmitted has greatly reduced the transmit battery power and greatly extended the operational life of multiple payloads.
In addition to recognizing and generating tones, the device was designed with 4 reed relays on board. The contacts on the relay are brought out to the terminal strip so no electrical connection is made between the PicDTMF's circuitry and the device controlled (isolated). This has proved useful in reducing unwanted interfearance between the other payloads and this circuit. Specifically the PicDTMF' digital clock may cause interfearance in other circuits and other transmitters could interfear with the PicDTMF.
The commands are keyed into a transmitting radio with a built in keypad or a Touch tone dialer.The commands (from the source code file) is Here
A newer version of the old PC board is currently on order. This one will add N-Channel FET cutdown circuits and possibly RC servo outputs. The RCservo will probaly need a considerably different command set.
Fig 1. A view of the top of the unit.
(Old unit w/ cheap terms, old xtal etc)
Last Revised: 28JUN2008