UHF Channels stop Scan

[GSHastings]

I'm new to current scanning, having just purchased a BCP996P2. Turns out, that scanner is significant overkill. I live in Mayberry, and the few channels here are "conventional".

After loading in the public service channels from Radio Reference, there are two UHF channels which always hang the scan. They seem to do this because both have some kind of perpetual hiss being transmitted.

I have tried to adjust the Squelch control for those channels, but that hiss cannot be squelched away. So, every time the scanner lands on one those channels, it assumes that it is active, and will hang onto that channel indefinitely.

I have locked out both of those channels, and the rest of the scanning seems to function properly.

Those are the only UHF channels which are used in my area (according to the data imported from RadioReference).

So, I'm not understanding what is happening, or is wrong. I assume they are supposed to be used for something, otherwise why would they be included in the database?

Thanks,
Greg

 

[jonwienke]

Perpetual hiss indicates some kind of digital repeater or digital trunked system control channel.

it's quite possible that they are undocumented DMR, since the ability to decode DMR was only recently introduced. Unfortunately, it requires a payment to unlock. You may want to buy the DMR upgrade for your scanner so you can hear what is being broadcast on those frequencies.

 

[Delta33]

Perpetual hiss indicates some kind of digital repeater or digital trunked system control channel.

it's quite possible that they are undocumented DMR, since the ability to decode DMR was only recently introduced. Unfortunately, it requires a payment to unlock. You may want to buy the DMR upgrade for your scanner so you can hear what is being broadcast on those frequencies.

NOT necessarily. It could be a simple birdie, or IF interference from another device.

 

[GSHastings]

Thanks for the suggestion. I'm not able to try it out right now, but will soon. I'll come back with the results.

 

[GSHastings]

Not sure I want to spend $60 on the chance that it is DMR. I've tried a couple of DMR database resources (one was a maaassssiiiivve excel spreadsheet), and it the frequencies don't show up there.

The reason I have those frequencies programmed into the scanner, is that they are listed in the frequency database I imported from this website. The only thing different I can spot in the data for those frequencies, is in the column titled "Type". Those frequencies are listed as Type "F". Most of the other frequencies are types "BM", "M", or "RM".

I have been unable to locate anything which explains what "Type" refers to, or what Type "F" is specifically.

 

[GSHastings]

By clicking on the Call Sign for each of these UHF channels, it does appear that they are the input channels for repeater systems. One is for the county sheriff, and the other the city police. They use a central dispatch, which is only about 2 miles unobstructed line of sight from my house. I get traffic on the central dispatch channel pretty consistently. And I can usually hear both sides of the conversation.

I'll read up on how to best set up a repeater system.

Thanks,
Greg

 

[RFI-EMI-GUY]

I'm new to current scanning, having just purchased a BCP996P2. Turns out, that scanner is significant overkill. I live in Mayberry, and the few channels here are "conventional".

After loading in the public service channels from Radio Reference, there are two UHF channels which always hang the scan. They seem to do this because both have some kind of perpetual hiss being transmitted.

I have tried to adjust the Squelch control for those channels, but that hiss cannot be squelched away. So, every time the scanner lands on one those channels, it assumes that it is active, and will hang onto that channel indefinitely.

I have locked out both of those channels, and the rest of the scanning seems to function properly.

Those are the only UHF channels which are used in my area (according to the data imported from RadioReference).

So, I'm not understanding what is happening, or is wrong. I assume they are supposed to be used for something, otherwise why would they be included in the database?

Thanks,
Greg

By "perpetual hiss", do you mean it is uninterrupted or are they "bursts of hiss". If in is uninterrupted, you might want to rule out interference from a computer, computer monitor etc. I have a new BCD536HP I am setting up and with the antenna furnished (not external to my house), the scanner stops on several UHF channels that relate to RF emanations from my nearby computer monitors.

Unless RR indicates some DMR licensees of interest in your area, ("Mayberry") I would not spring for the DMR upgrade on the chance these might be DMR signals. You could record and post this sound and even compare with DMR signals recorded on other websites for comparison.

 

[GSHastings]

It's a perpetual hiss. It doesn't seem to be coming from any nearby electronic items. I have a hand held also, so can get quite a ways away from everything, and it picks up the steady hiss also.

But, one of the two UHF channels has stopped hissing for the last couple of days. So I have included it in the scan. So far, no further problems with that one.

Thanks,
Greg

 

[jonwienke]

It's probably some type of digital. But you would probably need to get confirmation what type of digital before buying a key for Provoice or whatever.

 

[sparklehorse]

I was over in The Dalles a few months ago and my scanner stopped on one, maybe both of those UHF frequencies. I don't know what those signals are, I just locked the channels out. I think, as you surmise, you're hearing all the Wasco public safety there is to hear on the other channels that are listed in the DB. The RR database is full of outdated or inacurate information. It is dependent on hobbyists such as yourself submitting the information. In rural areas there may be few, if any, scanner enthusiasts around to update the information when things change, or verify if what is listed is correct. If you're curious about what those signals are you could get one of the cheap SDR dongles and pipe that signal into Unitrunker or other software that might recognize it. Could be control channels for a DMR system, or NXDN, or something else altogether. Might even be P25. Once you know the signal type you could investigate further. And your 996P2 is hardly overkill, you have a P25 Phase II system right next door in Sherman & Gilliam county's system (Frontier Digital), plus WSP is using P25 right across the river, and the Oregon State Radio Project P25 Phase II system will eventually be fleshed out in your area as well. Digital is slowly replacing analog just about everywhere. Food for thought.

.

 

[sparklehorse]

Drilling down a little on those UHF frequencies I see both are licensed as type FXO, which means:

FXO - Operational Fixed Station - A transceiver which may operate as a link between two or more fixed locations. The designator is often used in radio link or SCADA telemetry systems. With the exception of certain frequencies, operational fixed stations are typically secondary to land mobile communications.


So they may serve as links to Sheriff repeaters in the southern part of the county or something similar.

.

 

[sparklehorse]

You could also ask a moderator to move this thread to the Oregon Forum where someone in that area may have more information.

.

 

[robertmac]

Unless I missed them, I did not see any frequencies posted. This may help narrow something down even in other areas of the country that have similar problems. For instance, I have been picking up a steady noise on 444.800 + or -. And no, these are not digital signals. They are largely just in my block, but I have also encountered them in other areas. I know 70 cms ham is secondary and there are door openers, weather stations. The UHF band is large so specifying frequencies might help to clarify if digital, control frequency or other users in the UHF band.

 

[slicerwizard]

It's probably some type of digital. But you would probably need to get confirmation what type of digital before buying a key for Provoice or whatever.

Digital signals don't hiss. Sounds more like an open carrier, birdie, etc.

 

[buddrousa]

Is the scanner located near your internet router and is this in open squelch

 

[GSHastings]

One of the frequencies is 453.4875. I have been listening to that channel on an old hand held (Realistic PRO-37), and it does have some voice communications on it. The RR database lists it as the Wasco Co. Sheriff.

I can't locate any local sources of the hiss (monitor, wifi router, computer, etc).

But, I have discovered that if I position myself in just the right way, with the handheld on my desk, I can make the hiss go away. And when it goes away, it is just like using the squelch. The hiss is there full volume, and then I move to the right location, and it shuts off instantly and fully.

So, possibly it is something in my local environment. I'll keep looking.

 

[GSHastings]

All good info, thanks.
That's kind of why I decided to keep the radio. As things progress, I'll get more benefit out of the capabilities of the scanner.
The frequency with the hiss I'm exploring right now is 453.4875. The scanner shows that there is an associated input frequency of 458.4875. So it probably does have something to do with linking various repeater sights together. Wasco county is a big county with lots of high hills, and roads down in gorges. There are about 6 sites scattered around the county for the Sheriff.

 

[sparklehorse]

<snip> So, possibly it is something in my local environment. I'll keep looking.

I'll bet not. Like I say, I've picked up a constant signal of some sort on that frequency when I've been over in that area.

.

 

[RFI-EMI-GUY]

These two sites have samples of various radio sounds most are what you would hear on an FM scanner or other receiver. Listen to these to see if any have a hiss you describe.

The remainder of the sample are how they would sound on a proper radio. For example Securenet DES-XL can be compared with P25 IMBE. The Securenet is really not that bad in that you can understand the inflection.

W2SJW - Radio Sounds

Digital Modes Samples

 

[GSHastings]

Using my handheld tuned to 453.4875, and my BCD99692 scanning the other channels (with 453.4875 locked out), I have been able to determine that when there is transmission on the UHF channel, the same transmission is simultaneously on one of the VHF channels in the mix for the county sheriff.

So it does have something to do with broadcasting to the other remote antenna sites scattered around the county.

I haven't been able to locate any source of the background hiss, but have found multiple locations where it abruptly and completely stops. Those locations are very specific and small. Moving the handheld just 1/2" around one of those locatons, will switch the hiss off and on (just as if you were twiddling the squelch control). But the squelch control has no affect on the hiss at all.