I believe the Motorola DTMF decoder resides in an expansion chassis. I've never
encountered a SAM so I don't know where it plugs in. As you said, both are rare
and none of the stations I need to control have an expansion chassis.
The other suggestions, while innovative, don't seem to decode DTMF, which is
what I want to use to control the repeaters. It can be over-the-air on the
input frequency, or using another receiver, however that does tend to
complicate things one more level. There's already a decent receiver built into
the MSF, so I'd rather use that, then I can shut down the repeater using a
portable or mobile radio with a DTMF mike.
Bob M.
======
--- On Tue, 1/13/09, nj902 <wb0...@arrl.net> wrote:
> From: nj902 <wb0...@arrl.net>
> Subject: [Repeater-Builder] Re: Repeater controller to be used with MSF5000
> To: Repeater-Builder@yahoogroups.com
> Date: Tuesday, January 13, 2009, 1:26 PM
> 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 Repeater-Builder@yahoogroups.com, "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. ..."
