Looking for some input on what radio system a vol agency s..

[ghurty]

In reference to the same vol. agency in my previous post.

They are spread out across a few sections of LA, and they currently have terrible reception on their radios, even though they have a repeater.

So he asked me if I know of any ideas. So I suggested perhaps using a land line to reach the other area, and rebroadcasting out from there. but they are worried what would happen in case the phone lines went down (earthquake, etc..)

They currently are on a UHF system.

Does anyone know if VHF would be better, or any other ideas?

Also, they have a problem that alot of times people are stepping on other transmissions. Would a digital system solve this problem? would that also increase the reception? How expensive are these systems.

i know this is not a technology board, but I just thought that being you are end users of alot of different systems, you might have some valuable input

Thankx

[Timmy]

In my Volley Service we have UHF radios in all the trucks. As I live in a rural area we have HF radios so we can talk to Melbourne but you can also talk to anyone from anywhere in Australia. We also have pagers, mobile phones car kits which give them extra service. We also just got GPS.

[Dustdevil]

When was the last time there was an earthquake in Louisiana? :?

And how is this a "Non-EMS Discussion" topic?

Anyhow, the lower the frequency, the longer distance the RF propagation, generally speaking. That means you can have more distance between repeaters in the VHF range than you can in the UHF or 800 mHz range. And those repeaters will be heard farther too. Unfortunately, these days the choice of what frequency range you choose frequently comes down to what is left over. In many urban areas, there are simply few VHF frequencies to be had. And no, digtal does nothing to increase your range or clarity. It shortens your range and makes everybody sound like Donald Duck.

Perhaps a better understanding of the organisation would produce a better understanding of the problems they face. Is it really an EMS agency? Or is it just a volunteer organisation that responds to help out in disasters, search and rescue, etc...? Do they respond to 911 calls on a routine basis, or is this a "call out" squad that goes to help some other organisation a few times a year? Do they have a dispatcher? Full time? Do they need one? How many units? What size area do they cover? What is the source of their funding?

[BushyFromOz]

Ummmmmmmmmmmmmmm................................

Hows about you talk to someone who deals in communication systems???

[ghurty]

When was the last time there was an earthquake in Louisiana? :?

Sorry, I was referring to Los Angeles, CA

And how is this a "Non-EMS Discussion" topic?

I tought since it was not directly medical. :?:

The Vol. organization, is basically a first responder group. Someone calls 911, then calls them. They respond in POV to the scene, they are equipped with AED's, O2, Trauma bags, etc... They themselves dont transport. They also assist the city in Search and rescue operations, as well as disasters (they crosstrain alot with the city). They have a dispatcher, but those are volunteer as well, and the way it works is they have the "emergency" line fowarded to different lines depending on who is dispatching. (there is no dispatch center). They have approximately 100 units in the city, while the area they cover is not that big, half of it is in the San Fernando valley, so their are the Hollywood hills in the way. Almost all of thier funding is donation based, but they are currently looking to see if they are eligible for grants for equipment (AED's, Radios, ...)

Thankx

[DigitalNY]

We can talk in hypotheticals all day,

If you wanted to maintain your current UHF radios / pagers...

Find a local comm's company and discuss putting up a second UHF site. Get a second UHF Frequency for the area to be covered by the new UHF site. Program it into your radios to replace your existing frequency in those areas, and add the old frequency as an additional channel for when that unit travels into the coverage area of the primary (pre-existing) UHF site. Use a pair of VHF radios with directional antennas (yagi's) to link the primary UHF site with the new one that's farther out to extend coverage area. The benefits of this would be not having to buy new mobiles & portables to replace your existing UHF ones. It would look similar to..

Site A &#40;Primary System&#41;			 <----->			 Site B &#40;Secondary System&#41;	 UHF Freq A					   VHF Link				  UHF Freq B	   462.550				   152.100/152.700			  462.575

For example, you have town xyz which is 20-30 miles from your primary dispatch center at city abc. You put up a new UHF site at town xyz. The units in that town use UHF Freq B (462.575). Their audio is carried across to a VHF Link to your primary UHF site at city abc where it is put out over UHF Freq A (462.550) for the rest of your agency to hear and is received by dispatch.

When it comes down to it, I would stay away from 800MHz, UHF Systems and trunking systems and would look at the possibility of a VHF system. VHF Lo-Band is going the way of the dodo and is being replaced by multi-site VHF systems in many areas of the country. This includes upstate New York where I'm located. A multi-site VHF system would give you a very wide coverage area (possibility of 2000sq mi+) and a single VHF site can give 1000sq mi under good conditions.

You may also be able to tweak your existing UHF system for better coverage. What's the power output of your current UHF repeater? Is it simplex or duplex (do your radios transmit on a different frequency than they receive on? If duplex what style / brand / model of duplexer is present at the repeater? What is the HAAT (Height Above Average Terrain) of the antenna at the repeater site? What kind of antenna is it and what kind and what length of feeder is it being fed with? What kind of mobile / portable radios are you using in those areas that have marginal coverage? What is their power output and are you using gain antennas on your mobiles?

There are too many options and variables present to give rock solid advice on a forum such as this. Go with the sure ways of improving reception and range which is always better antennas, higher with better feedline!

All the frequencies in this scenario are made up and pertinent to the scenario.. I pulled the VHF freq out of the air and the UHF Freq's I used were FRS Frequencies, I wouldn't go using them for EMS ;-)

Ric

[Dustdevil]

All excellent advice. Another option that may work well for such a small, low volume agency, is rented or leased radio service. There are communications companies in the Yellow Pages that have repeaters already set up all over the LA area and rent time on those repeaters to businesses and other users. The system is already engineered, already in place, and has known coverage. You just have to negotiate a price with them, which you may get reasonably as a non-profit organisation. If you find one that is on UHF, then you have no equipment to buy. Also, of course, there are Nextel systems that may suit your needs.

Chances are, from the type of organisation I am picturing, putting up your own system is simply not at all feasible financially or operationally. Let somebody else's system and expertise work for you.

Good luck!

[Don1977]

My VFD uses VHF and my EMS uses UHF, UHF is better, travels further, Ive been able to talk to dispatch on UHF 50 miles away, freaks them out but ive done it. My VFD is switching to UHF within a month, should be interesting.

[Dustdevil]

My VFD uses VHF and my EMS uses UHF, UHF is better, travels further.

Actually, any Ham operator or communications engineer will tell you that the complete opposite is true.

You may find a UHF system that is stronger and better engineered for greater distance than a VHF system. However, that is comparing system to system, not band to band. Comparing band to band, VHF will always have greater distance, with the exception of occasional atmospheric nuances.

There are decent reasons to choose UHF over VHF, but do NOT do it thinking that your range will be increased. It will not unless you do the very same things that would have made your VHF range greater.

[Richard B the EMT]

Hows about you talk to someone who deals in communication systems???

Admittedly, they would want to sell you a system featuring their radios, but contacting, first, a radio and/or system manufacturer like Motorola, Johnson, or Bendix/King might be an excellent idea. Then contact any of your local companies using a "Community Repeater", like a car tow service, or a radio dispatched taxi service, for references to who supplies their radios and/or radio services. Next, contact your area RACES, or ARIES, Ham Radio emergency communicator groups, and the local Citizens Band REACT groups. The Ham groups might be accessed by contacting the American Radio Relay League, at http://www.arrl.org , and REACT International at http://www.reactintl.org/public/ . I close this entry with 2 mentions, first, the radio manufacturers I mentioned are not endorsements, they are just 3 that I remember off hand, and second, don't restrict your searches for information to any of the groups I mentioned, either collectively or by name. There's probably a bunch more out there. Edited April 2, 2010 by Richard B the EMT