[Trunkcom] MultiNet -Lonnngggg

Sat, 05 Jan 2002 00:25:15 -0600

First of all, the equipment that EFJ puts out uses the same parts, tx,
rx, pa's etc. is identical for LTR and MultiNet. The only "heat" problem
would come from the power amps on the transmitters.  If the people who
maintain or installed the system failed to use pa's that could handle
the load, that is the fault of the installer/maint personell.   I worked
for a company here in MS that has if not the only privately owned
multinet system, then one of very few. Most are owned by govt agencies.
We mixed both public service and commercial and private users on our
system. We actually had a mix or standard LTR, Americom (another
"enhanced" ltr versio from EFJ) and Multinet. The only real difference
in equipment was the controllers used  on each. 
LTR does not que anything. It is simply individual controllers that
share a common data bus with a data stream sent to the mobiles that
allows the mobile to access the other repeaters, provided their channel
data is programmed into the mobile.  If a channel is programmed into a
mobile, it still is not accessed unless the data stream from the
repeater controller says that channel is there. When a mobile ptt is
pressed, the radio looks at its home channel and checks if it is busy or
not. If it is free, the radio will transmit a burst, unkey and look for
a response from the repeater with a data stream that contains the
mobiles, home chan, user id, goto chan, free chan, etc, etc. The mobile
sees the goto chan number, looks in its memory program to see if it is
programmed, if so, it changes to the goto chan and repeats the above
until the handshake routine results in a free chan on the system that is
also programmed in the radio. The system may or may not have a
validation system. If it does, and the user is invalid, it is told to
goto chan 31.  Channel numbers in the data stream have nothing to do
with actual frequencies. Simply the chan on the system. The chan slot in
the mobile contains freq data.
Americom has que capability in the switch. tx and rx equipment same as
ltr and uses the same basic chan, id scheme as LTR with enhancements
which include over the air programming, kill, etc. Americom systems can
use a mix of both LTR and Americom radios at the same time
Multinet, however only uses multinet radios. LTR, Americom, Motorola,
GE, etc are not compatible with Multinet.  The MN system can have as
many channels as desired. Channels can be added and deleted as desired,
except for control channel, because the system tells the radio to go to
a "FREQUENCY" not a channel. However, multinet radios can be programmed
with LTR systems. The only difference in LTR radios and Multinet radios
is the firmware of the radio (bios chip for computer types) that
controls the protocol used. I have converted many radios from LTR to
MN.  Where LTR sites are independent and function without contact to the
outside world, MN sites are controlled by a centralized controller.  All
audio from each repeater at each site is brought back to the central
location. It disposition is determined by programming in the switch and
is patched back to the originating repeater, or simultaneously to two or
more sites for simulcast.  It has the capablility of individual user
identification (called UID) and user access to functions such as who
they can call, make telephone calls, make individual UID calls, unit
disable, enable, automatic site registration, and on and on. MN has
priority assignment for each user so that higher priority users can bump
lower units off where LTR has no allowance for this.
LTR and Americom dispatchers do so from a radio with a microphone. 
Multinet dispatchers have consoles that are nothing but a 486 or higher
computer running a console program with a card installed that sends and
receives data to Network controller. Audio is patched into the same
cable and enters the system where it is switched to different
transmitters at different sites as programmed and selected.  Regular
conventional and whatever radios can be connected to a MN system and
cross connected throught the RNT.  If maintained properly, a MN system
is extremely powerful. If not maintained properly, it can be a real
nightmare for the user.
LTR phone lines tie directly to RIC's (like an autopatch), MN and
Americom have switches like a PBX that shares resources. Phone lines,
radios, controllers, etc, etc. 
Oh, Americom systems must register each user on each site, the switch at
each site is constantly calling home to update its programming, dump
call records, validate phone calls before they are made and validate new
users that are registered since its last update.
Americom is no longer supported by EFJ. Only radios I ever saw were
either EFJ or Uniden
Ltr is alive and well. Radios by several manufacturers, mix and match.
MultiNet has been superceeded by a newer version that has even more
capability than the ones I worked with.
Brian J Cathcart wrote:
> 
> On Fri, 4 Jan 2002 20:04:18 -0500 (EST) JEFFREY MICHAEL KENYON
> <[email protected]> writes:
> > Also, like many EDACS systems I haven't heard too many good
> > things about LTR.  Of course Chester County, PA's system has had some
> > problems from what I've heard, and  so has Martin County, Florida
> 
> Everyone, let's keep this straight, you are confusing LTR and Multi-Net,
> they are two different animals.  The systems getting complaints are
> MULTI-NET, not LTR.  martin County, Fl and Chester County, PA are
> MULTI-NET systems, not LTR.
> 
> >  What customers are there that are actually  happy with their LTR
> systems?
> 
> Almost everyone I've talked to.  LTR is used by businesses and it is a
> good, simple, and inexpensive way to trunk.  And it is very reliable.
> 
> --
> 
> The Scanner Dude
> Brian J. Cathcart - KE4PMJ
> South Florida Trunking Guide - 5th Edition (On CD-ROM too!)
> Palm Beach County Frequency Directory - 4th Edition (On CD-ROM too!)
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