UHF or VHF

[fortsmithman]

What does your agency use. My service uses VHF.

 

[Mountain Res-Q]

We (Sheriff's Office / SAR) recently changed from a low-band VHF to a high-band VHF. The quality in signal is better but weaker, which meant more repeaters in our area. It also meant all new radios, a new dispatch center, and more glitches than you'd believe.

In my county the only agencies that use UHF is the Ambulance, but because of the terrain they have issues with communicating with dispatch or the hospital via radio if they are more than 30 minutes away from them, and the edge of county is 1.5 hours away from dispatch. Everyone else (Forest Service, Fire, Police, and Sheriff) uses High Band VHF (136-174 mHz).

 

[emtfarva]

that is kinda an unfair poll. My service uses VHF for our company radios but we also have fire radios that are UHF. We also use those too. Plus our comms with the hospitals are made with UHF radios also. I would have added a third option to the poll.

 

[lightsandsirens5]

We use VHF for all comms. 154.400 is our main freq. Why do some use UHF? Is there an advantage? I've always heared It dosen't have the range that VHF has. (Comparatively speaking)

 

[firefighter89]

All county fire and rescue squads are on VHF and EMS is on the statewide 800mhz system.

 

[MRE]

We use VHF for all comms. 154.400 is our main freq. Why do some use UHF? Is there an advantage? I've always heared It dosen't have the range that VHF has. (Comparatively speaking)

UHF requires less bandwidth for equivelant transfer of information than VHF, but it propegates less, so your signal will tend not to travel over hills and mountains as much as VHF.

 

[lightsandsirens5]

^

Ahhh...Thanks!

So essentally UHF is easier to Tx while VHF has a greater range?

 

[MRE]

^

Ahhh...Thanks!

So essentally UHF is easier to Tx while VHF has a greater range?

I actually need to correct myself, the bandwidth stays the same regardless of frequency, but the higher bands are much larger, so there is space for more "channels". The percentage of the entire band that you take up on UHF is smaller than it is on VHF.

Calling it greater range isn't necessarily correct. Lower frequencies will be better for mixed terrain, but when you have a line of sight between two radios, UHF could be better.

If you want to look at the hardware, as frequency goes up, the size of the components and antennas go down, and constructing circuits gets more difficult. You also need better quality components that can react faster since the frequency of oscillation is greater. Signal loss in the same materials is also greater for higher frequencies, so better quality coaxial cable and signal carrying circuitry is required.

 

[emtfarva]

UHF also works great in an urban enviorment.

 

[firemedic7982]

We use UHF. But then again Houston has a pop of over 3 mil, and is completely flat. err...except the overabundance of freeways, and their overpasses.

 

[eynonqrs]

Where I volunteer for, we use VHF for the county and our "ground" channel. The hospitals have recently got UHF channels for Ambulance to Hospital. The problem was that we only have one EMS channel, and you would get stepped on in the middle of a report because they had to dispatch a unit. For the private ambulance I work for, we use UHF, but we also have a VHF backup channel. I like VHF better. UHF is good when you are in an area that you will be in high rise bldgs. The higher the frequency will penetrate objects. If you were on low band VHF on the 11th floor of a high rise, good luck getting anyone.

 

[jtb_E10]

Neither....800 Mhz..not a huge fan of it though...

 

[MrRevesz]

Both UHF and VHF

 

[ResTech]

Fire and EMS are dispatched on low-band... EMS field ops are on UHF. Given the wavelength of UHF, it is said to be better suited for urban areas due to better penetration of buildings, walls, etc.

 

[lcfr09]

we're paged out over VHF, but for everything else we use the SLERS system which is 800mhz, we only use UHF for communicating with the hospitals which is slowly getting phased out due to the implementing of the MOTOBRIDGE from Motorola....

 

[NomadicMedic]

The county fire radios are 800mhz, Ambulance/Hospital comms are on the VHF "HEAR" radio, 155.34...and we're dispatched via MDT and Nextel.

 

[Hal9000]

156...

We live in a bunch of mountains.

Still a bunch of places don't get any service.

 

[ericg533]

Neither....800 Mhz..not a huge fan of it though...

800 MHz is UHF. Anyways, my FD uses 800 MHz, but we have backup VHF radios in every rig, which we have never used. The dispatch channel is simulcast over VHF for the pagers.

 

[mycrofft]

Nextel

Doesn't work in half the locations we see or respond. They wont give us UHF like the officers have.

 

[Akulahawk]

In Sacramento County, the 911 system is all 800 MHz digital trunked stuff now. When you're within range of the repeaters, you're golden. Unfortunately, that band doesn't seem to have the range that lower bands do, I suspect this is mostly due to atmospheric effects absorbing some of the signal. There's a reason why the CHP uses VHF-Lo (36-42 MHz) for their communications... the signal carries VERY well over long distances.

Santa Clara County now has their entire EMS system using 800 MHz channels with a 460? MHz channel being used for dispatch simulcast. It used to be used for BLS stuff... Been a while since I've looked up the old "control 9" frequency...