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  #1 (permalink)  
Old 04-30-2010, 11:23 AM
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Default Commercial Radio - In vehicle repeater

My company is looking into finally getting rid of nextel and going commercial radio.

The problem is that we are in a geographically challenged area for hand held (HT) radios. Meaning we would need about 4 repeaters to cover our entire area (approx. 16sq miles. 4mi x 4 mi).

Our staff is often away from the vehicle they are assigned and would need to be able to communicate via HT at all times. The operator is rarely more than 1/2 mile from his vehicle.

I was thinking we could setup each HT to transmit with a specific sub tone to its parent repeater inside the operators vehicle. This would operate similar to CHP HT -TO - MOBILE, or a HAM Cross-band repeater.

Each HT would be assigned to a specific vehicle (mobile repeater) by PL Tone.
HT A = VEHICLE A, HT B = VEHICLE B ....

Example:
All Hand Held radios (HT's) would transmit on 461.525, and receive on 466.525

All vehicles would receive on 461.525 and re-transmit on 466.525
---------------------------------------------------------------------------------------------------------------------------------

Hand Held - A - TX 461.525 PL 123.00HZ @ 5 WATTS // [RX on 466.525 PL 100.00HZ]

TO

Vehicle - A - RX 461.525 PL 123.00HZ ///RE-TRANSMIT/// TX on 466.525 PL 100.00HZ @ 50 WATTS

(Basically A mobile non fixed repeater for each vehicle and operator, separated by PL input tones)
---------------------------------------------------------------------------------------------------------------------------------
Is this technically legal for commercial use for a private company?

Thanks yall...

Last edited by DANEMSPRINGER; 04-30-2010 at 11:27 AM..
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Old 04-30-2010, 11:59 AM
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What you are thinking about doing will work in band, but the filters required are costly. Going crossband is a much better option. Also you don't need to worry about setting different PL tones for each handheld/vehicle as the newer vehicular repeaters are capable of detecting other vehicular repeaters on scene and in essence trurning them off until the active repeater is out of range.
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Old 04-30-2010, 12:11 PM
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I'll tell you that I consider myself to live in an area that is "geographically challenged" and my 5W 2m HT can hit our repeater no problem above some shear limestome wall faces. The antenna repeater is really high and provides coverage no problem. 16sq miles isn't asking much. What type of "geographical challenges" are we talking about?

But, as twowaytek mentioned, if necessary, consider cross-band operation. A lot of physical space is required for the repeater's duplex filters, since the input/output are only separated by a few hundred kHz.. I've seen 2m filters at about 2.5ft tall and 70cm ones about a 15 inches tall. This page discusses some aspects pretty well.
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Old 04-30-2010, 12:15 PM
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I agree with twowaytekk.

From a "near" perfect operation standpoint, and to minimize the business employee liability issues that can present themselves in varying vehicular repeater location usage scenerios, I suggest considering the following:

http://www.pyramidcomm.com/pdf/broch...0_Brochure.pdf
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Old 04-30-2010, 12:16 PM
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Default Vehicle repeater and range required

Sir:

You need to explain how your geography does not allow coverage by walkie talkie for the distance required.

A properly installed repeater should and could cover the range you listed. By properly installed I mean proper antenna, feedline, location, and if needed receive preamps.

Thanks,

Mike CGPD305
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Old 04-30-2010, 12:24 PM
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Very Cool...

Quote:
Originally Posted by Squad10 View Post
I agree with twowaytekk.

From a "near" perfect operation standpoint, and to minimize the business employee liability issues that can present themselves in varying vehicular repeater location usage scenerios, I suggest considering the following:

http://www.pyramidcomm.com/pdf/broch...0_Brochure.pdf

Last edited by DANEMSPRINGER; 04-30-2010 at 12:26 PM..
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Old 04-30-2010, 12:37 PM
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Quote:
Originally Posted by DANEMSPRINGER View Post
Not to sound too rerarded, but what does this lil device do? how does it work?
When it is mounted in the vehicle and connected to the high power UHF mobile radio, it allows a handheld portable radio (within communication range of the vehicle) to access the wide area UHF repeater.

As twowaytekk pointed out, it will be advisable to use a VHF highband portable radio/vehicular repeater if a UHF high power mobile radio is to be used. This is referred to as crossbanding. It minimizes potential interference between the mobile radio and vehicular repeater when they are transmitting and receiving at the same time.
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Old 04-30-2010, 12:39 PM
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I really appreciate yall's input,

I am familiar with cross banding in the "ham" spectrum(s), however...

Is cross banding legal in the "Industrial/Business Radio Pool" spectrum(s)?



Quote:
Originally Posted by Squad10 View Post
When it is mounted in the vehicle and connected to the high power UHF mobile radio, it allows a handheld portable radio (within communication range of the vehicle) to access the wide area UHF repeater.

As twowaytekk pointed out, it will be advisable to use a VHF highband portable radio/vehicular repeater if a UHF high power mobile radio is to be used. This is referred to as crossbanding. It minimizes potential interference between the mobile radio and vehicular repeater when they are transmitting and receiving at the same time.
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Old 04-30-2010, 4:33 PM
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Motorola, for one, sells canned systems designed for this function. Since it appears from the OP that a new system is being designed and built for their application it may be best to include this function as part of the system's specs. That way it will be 100% legal and any issues with getting the pieces to work together as required would fall on the company that designed and built it.

One thing is certain, if you add something yourself, the shop will always say that's what is causing the problem. If you make them add that something, they'll have to support it later on.

Here are some examples:
http://www.motorola.com/Business/US-...m+(DVRS)_US-EN
http://www.rfwiz.com/VXR-1000_InfoDat.htm
http://directory.officer.com/product...cular_Repeater

Last edited by n5ims; 04-30-2010 at 4:39 PM.. Reason: Added examples
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Old 04-30-2010, 8:52 PM
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16 Sq. miles is really nothing, and portable coverage shouldn't be that hard to obtain, unless they are using a simplex frequency. A good VHF or UHF repeater (heck, even a poor one) should be able to cover this at moderate antenna height (30-50 feet above terrain on a high spot) and provide 80-90% portable coverage.
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Old 04-30-2010, 11:56 PM
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I would agree that there must be some pretty rough terrain that 16 sq miles would need 4 repeaters!

The worst thing to do is reverse the freqs in a portable and try to TX to a mobile. Even with different PL's, this will be a headache.

In band vehicle repeaters are possible although thought must be given to frequency spread and or filtering of some sort. Cross band vehicle repeaters are the easiest to get up and running.

I have used Pyramid products numerous times and for the most part work well although there is a quirk with the repeater hierarchy scheme when mobiles are close together. If you call them, they are more than glad to help you through what is required to get a system running.
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Old 05-01-2010, 6:59 AM
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We have a VHF repeater behind the seat in a firetruck.
Our problem was talkback range, we could hear dispatch, but they could not hear us.

So the repeater is 30 watts with a about a 4 MHz spread. And a mobile duplexer.
We transmit on a separate frequency to the truck repeater, and the truck repeater transmits on the dispatch repeater input.
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Old 05-01-2010, 7:29 AM
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Maybe using 4 synchronized simulcast FB2 will be cheaper than buying a MO3 for each vehicle.

Maybe putting the MO3s and portables at 451 Mhz would be an option.

Peter Sz
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Old 05-02-2010, 3:55 PM
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Maybe even 4 steered FB2.

Peter sz
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Old 05-03-2010, 3:34 AM
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I thought there were some MO3 freq. down in the 405-420 range?
And if the mobile-xtender only TXed at 2 watts into a quarter wave, its not going to desence the main vehicle radio. and if the main vehicle radio only transmitted say, 10 watts to the repeater, it probably would not desence the mobile extender. An area of 4 mi x 4 mi?
That is about a 3-4 mile radius from a center point?
I agree, a repeater using good parts on a 50-100 tower in the middle of that area. The mobiles wont have any problem getting back using 10 watts.
Steven
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Old 06-04-2010, 4:08 PM
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Cool

(Does anyone offer this setup for LTR?

A littlebackground: last night I field tested a local LTR repeater using two HT's (one at a fixed location, and the other with me in my truck), and as luck would have it most areas were covered however we still had some deas spots. Keep in mind, my company has a limited budget, and we need to keep things as simple as possible (we have some not so smart people who will be using the radios).

The objective at this point is to supply 10 feild personel with HT's, the HT's will need to work while sitting in the vehicle and away from the vehicle all while clipped on the belt with speakermic's. My company is so far impressed with the LTR repeater, however I forsee a technical limitation... 1) keep it simple -- meaning I think a in vehicle repeater capable with UHF LTR would be the best bet, thus no mobile radio / strictly HT (more confusion for not so technical people).

Example: (HT )>to> (in vehicle LTR repeater) >to> (FB LTR repeater)
(to keep it simple for the end user)

???

Quote:
Originally Posted by Squad10 View Post
I agree with twowaytekk.

From a "near" perfect operation standpoint, and to minimize the business employee liability issues that can present themselves in varying vehicular repeater location usage scenerios, I suggest considering the following:

http://www.pyramidcomm.com/pdf/broch...0_Brochure.pdf
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Old 06-04-2010, 5:26 PM
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Quote:
Originally Posted by DANEMSPRINGER View Post
(Does anyone offer this setup for LTR?
The brochure clearly states;
LTR , EDACS and Motorola Trunking Compatible


Mike
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Old 06-04-2010, 6:15 PM
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Quote:
Originally Posted by DANEMSPRINGER View Post
(Does anyone offer this setup for LTR?

keep it simple -- meaning I think a in vehicle repeater capable with UHF LTR would be the best bet, thus no mobile radio / strictly HT (more confusion for not so technical people).

Example: (HT )>to> (in vehicle LTR repeater) >to> (FB LTR repeater)
(to keep it simple for the end user)
One way to do that is just hide the mobile radio in the trunk...the user never touches it.
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Old 06-04-2010, 6:16 PM
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Quote:
Originally Posted by mdulrich View Post
The brochure clearly states;
LTR , EDACS and Motorola Trunking Compatible


Mike
Based on my knowledge of the Pyramid product - that means it will interface to those radios and operate with trunked systems (delayed PTT, etc). It does not mean it supports those protocols native to the device.
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Old 06-05-2010, 2:37 AM
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So its now clear, I'm retarded... lol. Oops

Quote:
Originally Posted by mdulrich View Post
The brochure clearly states;
LTR , EDACS and Motorola Trunking Compatible


Mike
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