Motorola had two factory options that would allow control of the MSF5000 station, the DTMF decoder and the SAM [Station Access Module].
The SAM card can respond to DTMF, MDC, and other signaling formats and is the most versatile. It was also referred to as the Smart Wildcard. Unfortunately, they are pretty rare, although they sometimes show up surplus since they were used in certain 800 MHz RDLAP mobile data base stations that are at end of Motorola support life. Lacking one of those decoders, a simple solution is to use a Maxtrac. You can do that two ways. For either case, you need a way to get the control function into the station. For CXB stations there is one programmable input line available unless it's already in use. If so, or for CLB stations, an expansion tray with a wildcard is the best way to put signals onto the station's MUXBUS. For example, to control a repeater, you configure an input for 'repeater knockdown'. The first way to use the Maxtrac as your decoder would be to simply connect a decode output from the Maxtrac to your configured MSF repeater knockdown input. That Maxtrac can be configured as a receive only radio on a different frequency than the repeater input. The use of a different frequency is a common sense approach to supervisory control. That radio could also be configured to transmit back an acknowledgement if desired. In order to have the Maxtrac decode DTMF you need a small option board or you need to duplicate that circuit on a perf board. Using MDC, however, doesn't require anything extra. A second solution is to use just the Maxtrac logic board and install it in the same expansion plastic tray where the wildcard board is. Over the air control on the repeater input is acceptable for some applications, for example, enabling one of several mutual aid repeaters that have overlapping coverage or for other functions like enabling or disabling PL operation, changing RF output power level, etc. In this case, you simply feed the raw MSF receive audio to the Maxtrac logic board. It really has no way to know that it doe not have its own RF board. One more trick and an easy way to have several over the air functions from the Maxtrac decoder, is to use the Maxtrac display driver chip to provide your decode outputs. If the Maxtrac, either a complete radio or just a logic board that thinks it's a radio, is programmed for only one channel, its display will normally show the digit "1" at all times. The Maxtrac high tier signaling model has the ability to decode unit ID's and to 'alias' them, in other words to display a number corresponding to the ID received. For example MDC ID 1234 could show in the radio's display as "41". When the radio decodes that ID, it will activate the display segments to show that number. The extra segments, other than the ones that were active for the current channel display digit, are available as outputs to drive your wildcard inputs to set station states. The radio can have up to 99 different ID's in its list. There aren't that many unambiguous display segments available as outputs, but the segment lines could be configured to address a PROM or other simple circuitry to expand the decode capability. In other words, this idea is based on using something that's cheap and readily available - the Maxtrac logic board - to do the hard work of decoding. You could even configure one of these to use MDC ID's for a group of users to enable repeater access only for users that are in your decoder's list. You can even do this with a five pin logic board, one you have left in the parts pile after upgrading radios to use 16 pin boards. The TLN5172 trunking models of the five pin board will run the conventional firmware and initialize fine as conventional high tier signaling. After you initialize the radio, go to the option connector configuration and set everything to "NULL". You can make a pretty clean install if you put the display driver chip onto the wildcard's prototyping area. You can either salvage a chip from a Maxtrac front panel or, if all you have as a 2 mode front you can order a new chip . The chip is Motorola P.N. 51- 844373N25 which is actually a National MM5484N or equivalent. Bob, I can send you some pictures of a completed MSF project using this technique. It's sort of a "poor man's SAM card" ---------------------------------------------------------------- --- In [email protected], "Bob M." <msf5kg...@...> wrote: " I'm looking for a low-cost, simple, multi-digit DTMF controller to shut an MSF5000 repeater down for legal purposes. ..."
