Looking for Signal Improvement Tips

[CommunicationsFreak]

I'm looking for information/input/feedback from experts in LMR.

Is there way to improve a 5 watt signal from a VHF/UHF1-2/700/800 (either of the bands) portable radio in analog, P25 (Crypto, OTAR, etc.), MDC1200. Except for an antenna? Would a signal 5W in - 50W+ out amplifier/booster similar to the ones used in the military, work the same as a mobile radio (except for Tx time duration per PTT), if so would the cost be under $1.5K (mobile radio)?

Reason being, comes winter at 5 watts comms will not work well in P25 or analog, to cover 20+ miles.

 

[scannermanner1]

I'm not much of a comms expert but can't you find a mobile radio for under 1500$$ ? Vertex has several uhf. or vhf mobile radios for well under 1K. or am I not understanding your question correctly ?


To answer your question, then yes a HT connected to a amplifier will work pretty much the same as a mobile radio with a few exceptions of course like battery life, transmitt time, things like that.

 

[CommunicationsFreak]

I'm looking for information/input/feedback from experts in LMR.

Is there way to improve a 5 watt signal from a VHF/UHF1-2/700/800 (either of the bands) portable radio in analog, P25 (Crypto, OTAR, etc.), MDC1200. Except for an antenna? Would a signal 5W in - 50W+ out amplifier/booster similar to the ones used in the military, work the same as a mobile radio (except for Tx time duration per PTT), if so would the cost be under $1.5K (mobile radio)?

Reason being, comes winter at 5 watts comms will not work well in P25 or analog, to cover 20+ miles.

Forgot to add: This is for public safety/life dependent use.

 

[teufler]

Go with some kind of gain outside antenna. you are going to have about 10db gain for the 5 to 50 watts. then with a 6db gain antenna, you are going to have an ERP of 200 watts. you should lose about 2.5 db in the coax so about 100-125 watts out. so 5 watts compared to erp in 100-125 watts, that should help you. Don't know what you elevation is but if you have some height above average terrain, you should be good to go. If you are in a hole, all the power is not going to help much. If you have about 40' on your antenna, you should get 50miles of understandable audio.

 

[zz0468]

There are amplifiers out there, but really... the way to improve communications is to define and understand the particular problem, and then apply the appropriate fix. You haven't given us anything to work with other than to rule out the cheapest and most effective single solution - a better antenna.

 

[DisasterGuy]

Zz hit the nail on the head. You suggest there is a specific issue but are asking a very broad question. Specifically what is the application? What band? Simplex, conventional or trunked? Is this a portable, mobile or base application? What is the delta between the current and required RSSI? What service (fire/EMS/LE)?


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[WA0CBW]

Also don't forget to look at your license and see what power levels and ERP power levels you are licensed for.

 

[CommunicationsFreak]

There are amplifiers out there, but really... the way to improve communications is to define and understand the particular problem, and then apply the appropriate fix. You haven't given us anything to work with other than to rule out the cheapest and most effective single solution - a better antenna.

An antenna will not be of better use comes winter, even a radio tech that I know confirmed
it himself (doing a Tx/Rx test from a VHF portable).

 

[CommunicationsFreak]

Also don't forget to look at your license and see what power levels and ERP power levels you are licensed for.

NTIA station, without power limit, operating in VHF FM.

 

[CommunicationsFreak]

Specifically what is the application? What band? Simplex, conventional or trunked? Is this a portable, mobile or base application?- Simplex, Duplex/repeater, P25, analog, USCG VHF, and 141-162MHz, from portable (stated in original posting).

The station is privately funded, due to budget cuts.

 

[DisasterGuy]

Your comments regarding the antenna just don't hold water and I don't follow the logic about winter. Your signal will be impacted by only two factors under your control: ERP and HAAT. The most expensive (and least efficient) way to increase ERP is via the actual transmitter power. The least expensive and most efficient way to increase ERP is via your antenna and feedline. The HAAT you don't have much control over short of a tower.

If you are looking to do this with a portable that remains a portable rather than being inserted into a vehicle adapter with either a mobile antenna or fixed antenna there is no real solution available. If however you were to use a vehicle adapter with a 50w amplifier and 5/8~ mobile antenna (3dBd) you would increase your ERP from around 33-34dBm to around 50dBm (100w).


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[zz0468]

An antenna will not be of better use comes winter, even a radio tech that I know confirmed
it himself (doing a Tx/Rx test from a VHF portable).

Then an amplifier won't help, either.

Usable reception boils down to signal to noise ratio. The signal MUST exceed the noise (internal, external, natural, manmade, etc.) by a specified margin. Gain is a tool to use in establishing that S/N ratio, and from the far end, you can't differentiate between amplifier gain or antenna gain. It's gain, and it adds up, regardless.

Now, if you're already running as much antenna gain as is feasable, and your S/N ratio at the far end is still deficient then, yes, an amplifier would be the next logical thing to look at. Where the amplifier might go is still undecided. It could mean a low noise preamp on the receiver at the far end of the path.

And I have to ask... what does winter have to do with it?