LTR for Emergency services

[bradlington]

Hi

Being involved with MPT1327 systems only and new to LTR (theory only) I have the following question.

For a reasonable sized metropolitan area what is the answer to migrate from seperate systems onto a single trunked system.Besides MPT 1327 as an option-what else is the next best thing-Analog -and key up time is important and must be open arch , not proprietory
Any comments on LTR ??

Thanks

Brad
South Africa

 

[INDY72]

For analog only systems.. LTR is a graet way to go,.. and if you go LTR Passport, you get added growth potential, security options.. and can run both Standard LTR, and Passport type TG's. Any other type of system can be patched in, as is true with any TRS. With an LTR system you have cheaper mobiles and HT's than say an ASTRO Digital System, or EDACS Provoice, and can get supplied by many manufacturers.

For instance.. the Motorola HT1250-LS+ is cpable of both LTR and conventional at the same time.

Also in the LTR Game are Tait, EFJ, and Kenwood.
I also believe that encryption is available for LTR.

 

[LTR]

I agree with milf, if it needs to be analog and non proprietary, LTR or PassPort protocol would be the choice.

PassPort will allow you to network sites if you need more than one to cover an area. LTR is single site unless you have the user manually change talkgroups.

Also to add to the HT1250LS+ comment, it will do LTR, Conventional and PassPort in the same radio, as does it's mobile version the CDM1550LS+. Kenwood and ICOM make mobiles and portables that will do all three in one radio also.

 

[bradlington]

Hi
Thanks for the info and comments.
It is unfortunate that we in this country are not exposed to a large number of different trunked systems so the true expertise is limited.

I have been involved with an MPT1327 trunked system here in our country where I was directly involved in the system down to the radio software.I was responsable for the Taits bringing out the displaying of the Chan in idle mode and the fine tunning of the voting ACT NOW format.

Long story but still a passion.
I have since been and currently involved in GSM ans 3G.
I am still somewhat involved in the radio industry on a more voluntary basis for advising.

This is why I asked the original question:This municipality went from a multi stand alone site to a multi channel site with different CTCSS access for different geographical areas.
These worked ok and then along came a Tait Simulcast system that has proven to be the most disasterous system to date.At times the audio is so bad that some stations go on top reverse to get the messages through.This has got to do with having to manually train the system .Over catering the sites for the area-as planned for portable coverage on VHF.

Is there a site that has live audio so I could listem to the type of communications going on on an LTR system.

Due to the lack of understanding of radio systems here in our country it is normally the case of the salesman influences the person who is least knowledgable .(Of course there sale depends on the fact that their system can do the world)
Currently the main user interfaces are the likes of ICOM f3 and later and uhf F4 for ground fire control.Thus I take it that the LTR is the best suited to the continued use of current upgradable equipment.

QUESTION :Can a radio revert to a simplex or other channel if the radio is out of coverage .
Long but thanks in advance for any response.

Regards Brad South Africa

 

[DaveH]

I also believe that encryption is available for LTR.

I wouldn't mix up "encryption" with analog voice scrambling which is available on LTR. The only types I've ever heard of are speech inversion.,and it doesn't seem to be too widely used. Voice scrambling always has a downside for voice quality and/or range.

Dave

 

[bradlington]

Hi Dave

Thanks , I am fully aware of the encryption that can be used , I am sure VSB and simple inversion would work fine .
Regards

Brad

 

[INDY72]

With the HT's and Mobiles.. you can not only program in the multiple LTR Formats, but as stated conventional channels as well... This helps for not only being able to talk to the others if you move out of the "range" of the LTR's trunking coverage, but also for interop with other areas that you may have to work in.

Example: Simpson County, MS Law Enforcement-
They run a two site LTR Standard VHF system. Three freqs per tower on the LTR system. All of the HT's and Mobiles are also programmed with the conventional VHF freqs of each of the surrounding areas, statewide Hi band, as well as all the local conventional hi band freqs, and the EOC's conventional freqs. They will also be set up for the second LTR Standard system that is comming online for the E-911 District.

They are also adding the V-Tac, and V-Calling nationwide freqs .

LTR radios are very versatile for multipurpose usage. With just a couple of button presses you can switch between multiple LTR/LTR Passport systems, or go conventional.

Though they currently lack any digital format and thus are not APCO-P-25 compliant nor compatable, they are very good for analog usage. In a state that has mainly analog conventional hi band, or UHF, the LTR type radio is the best to go with. You only need one radio and can talk to most of the other systems in the state.

 

[bradlington]

Hi Mif

Thank you for the valuable input-kind of info that is worth reading.

The more I see the LTR functionality the more I like what I see.
I have not yet found the LTR standard , any ideas where I can download ?

I sincerely hope the metro make a move towards the right decision.

Kind regards

Bradley Glen

 

[DaveH]

Brad,

I'm not sure where to find "the" standard online, but it is covered by a number of US patents. It can be tough slogging with the legal jargon. They should be accessable but I can't give you specific numbers at the time.

Two older networked versions of LTR are LTR-Net (EF Johnson) and ESAS (Uniden). I may be able to dig up links for the patents. They describe extensions to LTR and back-compatibility on the same system. Interesting reading if nothing else.

Dave

 

[bradlington]

Hi Dave

Thant would be appreciated.

I understood that it is an open platform founded by EF Johnson , ok I must look into it.

Regards

Bradley Glen

 

[pro92b]

LTR is not an open standard and there is no document on line that I know of. E F Johnson has licensed LTR to various manufacturers, among them are Motorola, Kenwood, Icom, Uniden, Maxon, and Standard.

US patents that have some descriptive information are listed below.
5040237
5440759
5465386
5548802
5613196
5815799
6374115
6529486

The links below contain similar information and are easier to read.

http://home.hvc.rr.com/bpetrow/ltr.htm
http://www.optoelectronics.com/tech/pdf/ltr_faq.pdf

 

[INDY72]

What I was refferring to by Standard is the basic LTR format, as opposed to Passport LTR, and Multinet LTR.