UHF Remote Link

[james812]

Good evening.

I've been listening to a few of these UHF remote links lately and they seem to just be a low power simulcast.

Can anyone give me some insight to what they are used for? There has be be a reason.

I apologize I've searched the radio reference database and google and have not seen anything that relates

Another question

Is there any reason to use decoder program (like trunk tracker. Etc) to use on hi VHF? What I'm wondering is there any other information being transmitted? Besides the voice? I know dispatch can determine what unit is which, just by transmitting.

Again thanks for any information. I try searching but sometimes just can't get any relevant information

Hope everyone has a good 2013

73's

[kruser]

Originally Posted by james812

Good evening.

I've been listening to a few of these UHF remote links lately and they seem to just be a low power simulcast.

Can anyone give me some insight to what they are used for? There has be be a reason.

73's

What UHF links are you monitoring? I mean, what state and area in the state?
Have a link to the page here that shows these links you speak of?

There are thousands of UHF links in use across the country. That makes it rather hard for someone who may know the answer to give you an answer if they don't know what links you are talking about.

A little more detail would be most helpful!

In general, links are used for a variety of reasons but many times they may be used to link multiple receive sites to one control location. That is but just one example as there are many uses for them.
If you are lucky and in the path of one, sometimes you can receive from the link and actually hear traffic that may otherwise be out of range.
Many use pretty narrow beamwidths though so they can be hard to hear if you are not very close to the signal path.

Programs like Trunker or any of the modern day control channel decoding applications are just as useful on a VHF trunked analog or digital radio system as they are when used on an 800 MHz system. A lot of info can be learned from decoding the datastream from a P25 system.
So yes, they are very useful for VHF control channel decoding. Many associate those type programs with 800 MHz systems as that is where most of the first trunked systems were setup at. Now, you can find trunked system all over the typical scanner bands. Low VHF may be the exception. I've not heard of any low band trunked systems. I'd bet there is one out there somewhere though. Not sure how well it would work with the way propagation changes so much on that band and the potential for interference in the band.
I know there are telemetry signals on low band as well as scada data but can't say I've ever heard any analog or digital trunked control channel type sounds on low band.

[n5ims]

Originally Posted by kruser

What UHF links are you monitoring? I mean, what state and area in the state?
Have a link to the page here that shows these links you speak of?

There are thousands of UHF links in use across the country. That makes it rather hard for someone who may know the answer to give you an answer if they don't know what links you are talking about.

A little more detail would be most helpful!

The requested detail was there if you looked at the original post and thought about it a little bit. I would strongly suspect that the links are detailed on this page from the RR Database (Dubois County, Indiana (IN) Scanner Frequencies and Radio Frequency Reference) since the post is in the Indiana forum and the OP's location indicates that they're in Jasper (Dubois County). There is one entry listed as "Dubois County Sheriff - UHF Remote Link" and three more as "Jasper Police - UHF Remote Link".

[902]

UHF links are mostly categorized with a station class code of FXO for "operational fixed." These stations are used to link from point A to point B. Most of the time, they are licensed as low power operation, but can be higher. They usually (or *should*) use directional antennas that point to the other station, so you can't always hear them. They are also referred to as "Poor Man's Microwave" and fulfill transport like a DS0 microwave circuit or leased telephone circuit would, except they're cheaper (pay once and no recurring cost).

What are they used for? Simple audio linking back from a remote receiver in a dead zone for coverage, linking to a remote transmitter, voting receiver audio back to a voting comparator, and so forth. Basically, it's a "gazinta-gazoutta." What goes in on one end goes out on the other, usually in a unidirectional pathway, but sometimes it's duplex. They should not be locked on in transmit unless they are extremely low power, but that's usually ignored by vendors. You'll see fines from the FCC for that on occasion.

On the plus side, they're cheap. On the minus side, they are susceptible to interference from others on frequency and the audio characteristics of the link often limit the audio quality of the system. They also kill frequencies. One large VHF system can have dozens of UHF channels supporting it. The caveat is these FXO systems are usually secondary (unless they are on frequencies designated for fixed operation). That means another agency can apply for a license and effectively take these frequencies away from the original user without recourse. That makes most agencies just get leased lines or explore radio over IP connectivity.

[kruser]

Originally Posted by n5ims

The requested detail was there if you looked at the original post and thought about it a little bit. I would strongly suspect that the links are detailed on this page from the RR Database (Dubois County, Indiana (IN) Scanner Frequencies and Radio Frequency Reference) since the post is in the Indiana forum and the OP's location indicates that they're in Jasper (Dubois County). There is one entry listed as "Dubois County Sheriff - UHF Remote Link" and three more as "Jasper Police - UHF Remote Link".

I thought about that but then a lot of people do not post their true locations. Hence the reason for asking the question to make sure.
I suspect your assumptions are correct as I also looked at the Dubois County link and other areas nearby and saw the UHF Links.

Assuming things has landed me in a lot of trouble over all my years so I've learned to not assume anything including the location info supplied by the users here being true.

It's not much different then the user that posts, "What's wrong with my scanner?" and then never says what kind of scanner they are talking about and what problems they are having!

I'm just saying that it only takes a few seconds to copy and paste a link or add a little more specific info in with your question to make it easier for someone willing to help with an answer. That's all.

[james812]

Thanks for the information kruser, n5ims, & 902.

I did not include the location because I wanted general information, and yes those were the ones I was referring to.

902, you mentioning the dead zones makes sense, I feel that is the correct answer and what I was looking for. I pick them up often, but as mentioned VERY low power and difficult to understand at times.

There is little to no information on the wiki page, I checked. I try to research and read first before posting.

Any other information would be appreciated or further links to reading.

THANKS again to everyone, much appreciated.

[902]

My pleasure. Let me get my facts and rules notes together and see what I can do with a Wiki entry. Hopefully sometime next week.

[902]

Check "UHF Link" in the Wiki. If anyone can put something a better way or maybe I didn't quite hit on something right (or maybe I just got something completely wrong), please do edit!