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Model LT8R

Here's what the LCD is saying:    Homes H01, H02, H03, H04, H09 and H06 are set for clear channel (H).    Homes h17 and h15 are set for shared channel (h).    Home h17 is set for shared channel but is BUSY (not free to trunk to).    Homes 01, 09, 06 and 15 are idle (free to trunk to).    Home 02 in use by user 02150.    Home 04 in use by user 02178 trunked from Home 02.    Home 03 is sending CW ID. Note: 02178 means homed on 02, having User ID 178

LTR™ doesn't get simpler than this !

If purchased with 2, 4 or 6 channels, an LT8R can be easily upgraded to 4, 6 or 8 channels. Channels are added in increments of two by installing one 2-Channel board and two microprocessors into 40-pin machined collet sockets. Then simply plug the added repeaters into the appropriate rear panel connector (each repeater has its own pluggable connector), then setup the new repeaters.

If more channels are installed in the LT8R than you intend to use, you must disable the unused repeater slots by declaring them as Home 0 in their respective repeater setup areas. Then they won't be declared as free or display on the LCD.

2-Channel board - Note surface mount assembly.

Each repeater has its own connector / plug

Fully Self-Contained Controller

The LT8R is the first LTR™ controller ever offered with multiple channels completely contained within a single enclosure. No more annoying network cables. No more programming separate controllers. No more wondering if all channels are trunking. No more being in the dark due to lack of a system wide data display LCD!

Packaging all the controllers into a seamless package has huge advantages:

• Cost per channel is 1/4 - 1/2 of single channel controllers.
• All channels are programmed same place, same time, same way.
• All channels are adjusted same place, same time, same way.
• Adjustments for all channels available from the front.
• Common LCD gives system wide status of all channels all the time.
• LT8R Internal bus is much faster than external bus of single channel conrollers.
• Local and over-the-air DTMF programming is supported.
• It's OK to assign any Home No. to any Repeater No.
  Suggestion: you may assign RPTR 1 as Home 1, RPTR 2 as Home 2... RPTR 8 as Home 8. Easier to think about.
• Separate CWID message per channel.
• The LT8R (8 Channels) is smaller than any single channel controller made.
  19 x 7 x 1.2 inches... yep, just a bit more than one inch deep!

Every detail of setup is faster and easier than multiple single channel controllers !!

NOTE: The cutouts in the inner front panel are perfectly aligned over the adjustments. Close-up camera angle creates false illusion of misalignment. (Parallax)
All setup adjustments are clearly annotated and available from the front while the LT8R remains mounted and operating.

Programming

Method of programing
Since the majority of good repeater sites have no phone lines available, DTMF is the best choice. It works at all sites, is dependable and cheap. Once setup there is only need to enable and disable users occasionally... Completed in about 30 seconds with a DTMF handheld.

Local programming is performed using an ordinary DTMF telephone plugged into the front panel PGM port as a keypad and viewing the LCD's powerful programming data screens.

Remote programming is accomplished via RPTR 1. After sending the password code RPTR 1 is busied out when programming mode begins. Busying out RPTR 1 makes it unavailable as a trunk-to channel and users homed on it are trunked away when they make a call or are called. Thus RPTR 1 is free of two-way interference during programming.

Note: All user programmed data is retained in non volatile EE Prom memory.

Password
A four digit password code is user programmable. A board strap allows the choice of access code or not for local programming. The not choice makes setup much faster. A board strap allows a back door password code in case you forget your personal password.

Remote ReBoot
A reboot can be initiated remotely. Lightening or other causes can occasionally cause computer malfunction. Remote reboot could save a trip to the site someday.

Built-in Validator
A built in validator provides 20 separate Home programming areas where 250 UserID's per home can be separately enabled/disabled. Since there are 8 channels available a maximum of 8 of the 20 programming areas are used in a given installation. Users can be quickly enabled or disabled with quick over the air DTMF commands, or locally at the site.

System SetUp Area
All system wide programming is handled in the System SetUp area. This includes.. Area Code, Programming mode access code, CWID interval, CWID speed, LTR™ Baud Rate and more.

Repeater SetUp Areas
There are 8 separate repeater setup areas, one for each repeater. Each includes: LTR Rx data polarity, LTR Tx data polarity, This Rptr is Home No., COS Hangtime, COS polarity, Clear/Shared Channel, Enable/Disable Idle Msg and 10 characters of CWID message.

Navigation
There are a number of two digit quick commands that allow you to instantly navigate from any setup area to any setup area. Other two digit codes allow these powerful functions..

1. Disable all UserID's at any Home.
2. Get a listout of all enabled UserID's at any Home.
3. Disable all UserID's at all 20 homes.
4. Reset any repeater setup area to factory defaults.
5. Reset all 8 repeater setup areas to factory defaults.
6. Reset the system setup area to factory defaults.
7. Initiate CWID on all repeaters for deviation setting.
8. Exit programming mode command.

Considerable attention has been given to making the job of setup and management a snap.

Operation of the Repeater

Audio Quailty
The audio path from the discriminator to the modulator is processed with state of the art BI-FET op-amps and two 8 pole digital Butterworth filters. Higher quality audio simply does not exist. It's actually not possible to achieve higher linearity. We think you'll be astonished at the differance real engineering makes..

Hangtime
Many believe that LTR repeaters operate without input hangtime. Wrong. There must be hangtime to fill in the gaps between LTR words received from the mobile. Particularly those long gaps when the mobile is weak. At the end of each mobile transmission, a turn off code is sent which the repeater uses to terminate the hangtime and the repeater is declared free at that moment. Then the repeater responds with squelch turn off code to the mobile resulting in no squelch tail heard.

The question isn't if there is hangtime or not. The real question is how long is it? Competing controllers have a fixed hangtime which appears to not exist due to turn off code. The LT8R allows the system operator to set a hangtime per user. Likely you'll set most users with a fairly short hangtime while others that frequent weak coverage areas (also tunnels, parking structures etc) can be set for longer hangtime (up to 4 seconds). This will allow more fill time between mobile LTR words so that a communication can proceed in difficult circumstances. Remember that whatever hangtime you set, it is ended the moment the mobile unkeys and sends turn off code.

No other LTR™ controller gives you settable hangtime per user!

Clear / Shared Channel Operation
The LT8R has been designed to allow you to set each repeater as clear or shared channel in each repeater's respective setup area. Obviously all clear channels is the ideal but a mix of clear and shared channels will have a much better result than fewer clear channels. Why? Because a shared channel in reality is idle most of the time. With multiple shared channels the probability of one being idle at any given moment is excellent.

The LT8R can operate with as little as one clear channel. All users must be homed on clear channel(s). Channel(s) set for shared operation are declared free to trunk-to if not busy. If busy they are declared not free and remain not free for 3 seconds following activity (hangtime) thus protecting a conversation in progress (from trunk-to interference) on the shared channel.

The idle message must be disabled on shared channels. (The idle message should only be enabled on repeater/homes that have users homed on them.)

Handshake
The LT8R uses a separate processor per channel so that each channel's LTR interrupt can operate at highest priority. The recovered data in the LTR word is oversampled and hamming code correllated with the 7 bit error check word. If there is an error it is corrected with our advanced digital error correction algorithm. The result is a higher percentage of successful handshakes and communications than competing products.

CWID
A separate callsign message of up to ten characters can be set for each repeater. In addition the ID'ing interval ( 5 - 99 minutes ) and code speed (10 - 25 wpm ) are user programmable. The ID message can include any punctuation, numbers and many special CW abbreviations.. AR, KN, SK, HI etc each count as a single character.

A repeater is busied out during its CWID. A user homed on a repeater that is IDing is trunked to another home to make a call. Users do not hear the CWID as a result. When the repeater hosting Home 01 is sending CWID its LCD sector says "H01-IDing".

One of the two-digit quick commands (*99#) is used to make all the repeaters send CWID for the purpose of setting the CWID deviation per channel.

High-End Construction

The LT8R enclosure is made of aluminum sheet and formed into a rigid rack mount enclosure. All aluminum is plated and the front panel is painted in addition. The front panel, inner front panel and rear panel receive informative silk screening.

The removable rear panel gives access to the boards area for installing additional channels or firmware upgrades. A clever removable front panel gives access to all adjustments while the LT8R is still mounted and operating. All adjustments are annotated on the hidden inner front panel.

The boards are fabricated of the highest quality green FRP and are multi-layer containing ground and voltage planes for optimum reliability in an RF environment.. The 2-Channel boards are made using the surface mount process for high density. The Larger mother board has many connectors and microprocessor sockets so conventional thru-hole technology was chosen due to much higher connector fastening strength.

All socketed components (mainly processors and memory) are installed into the highest quality gold-plated machined collet sockets available for ultimate reliability.

Stated Simply, The LT8R is the Best Deal Going in LTR !!

LTR (Logic Trunked Radio) is a trademark of EFJohnson.