Question Around Licensing and Proximity To Others

[jackw414]

Hello All,

We are currently licensed for a set of frequencies but in searching the ULS I am noticing some oddities around proximity to others on the same frequencies.

Take for example a FB2 we have with the following:

Output power/max ERP 40 watts
Emissions designators: 11K2F3E, 4K00F1W, 7K60FXW
Locations include: 16 km around the fixed point of the repeater.

A quick search of the ULS shows someone 12 km away running an FB2 with the following on the same frequency:

Output power 50 watts/max ERP 25 watts
Emissions designators: 11K2F3E, 7K60FXD, 7K60FXE
Locations include 8 km around fixed point of the repeater.

The reason I ask is that as I sit with 3 HTs in front of me on that repeater (and within our radius around the repeater, quite close to it actually) something is transmitting on the RX frequency of the HTs (the TX for our repeater).

I have a few other frequencies on our licenses that fit the same criteria, someone in close proximity often is licensed on the same frequency and often for FB2 at 40-50 watts. Many of them are likely placing their repeaters on roofs like ours, we are in a suburban area north of the downtown, the one listed above is a BANT with a reported height of about 30 meters without appurtenances.

I know we got everything done legitimately via a coordinator, they were recommended to me by someone I totally trust, so I guess I was just wondering if this is normal or do we have a potential problem I should bring to the coordinator? I plan to make some improvements to our repeater infrastructure and would hate to have it being stepped on once it is finally working, right now it is pretty lackluster so it barely gets used. I would also hate to create interference for someone with a legitimate purpose to be using a frequency that they also licensed to, in this case the other user is a hospital, their coordination appears to have been done by a reputable company as well.

Again just not sure and would hate to potentially insult our coordinator by asking the question, but this seemed possibly problematic to me.

Thanks,
Jack

 

[mmckenna]

Frequency coordinators can make mistakes. Unfortunate, but it happens.

For most non-public safety users, there usually isn't a guarantee that you'll have your own private frequency. Usually they need to be shared in urban areas. Choosing PL/DPL codes is important.

It's also entirely possible that the other co-channel users are not following the limitations on their license. There's no shortage of people that assume "it doesn't matter", or "I'll do whatever I want", or "It's my private channel and I'll push everyone else off with more power".

Wouldn't hurt to reach out to the frequency coordinator and ask them "WTF?" if you think it's going to be an issue. They should be doing their job correctly. Upgrading your system shouldn't be an issue as long as you stay within the confines of your license.

But, ultimately, the FCC will say it is up to the individual licensees to cooperate and share resources. Licensees should cooperate.

 

[jackw414]

Another valuable lesson from you @mmckenna, thanks for your insight! I understand a good bit of the general technology but I am still learning some of the specifics on the Kenwood gear and FCC licensing so I appreciate your willingness to explain, it is remarkable how much of a mess the airspace is especially in urban areas the more I research.

It sounds like this is something for my coordinator to check out so I will get in touch with them, fortunately we are not using the repeater much if ever right now and I will be reprogramming all of our gear in a few months anyways so that gives me time to sort out any changes on the repeater if necessary.

Thanks Again,
Jack

 

[kf8yk]

Assuming these are Part 90 licenses, review 90.173. Coordinators select frequencies to minimize interference, not guarantee interference free channels or provide for the exclusive use of a frequency.

You have some leverage if you are the incumbent or earliest licensed user of a frequency. Usually any FCC restrictions or modifications in an interference case that fails to resolve by mutual cooperation are imposed on the newcomer.

 

[mmckenna]

it is remarkable how much of a mess the airspace is especially in urban areas the more I research.

There's been so much change that it's created this mess. Unfortunately it's not fixable without forcing everyone to change. That change would cost a lot of money, and no one is going to want to do that.

The UHF band isn't as bad as VHF. UHF (as well as 700, 800, 900MHz) mostly uses standardized repeater offsets. VHF, hasn't enjoyed this benefit. It's a real mess.

Also, many of the current frequencies were set up for the older 5KHz deviation radios, so there's now a lot of wasted space in the gaps. If entire bands could be refarmed into closer channel spacing, it would make life easier.

 

[jackw414]

Assuming these are Part 90 licenses, review 90.173. Coordinators select frequencies to minimize interference, not guarantee interference free channels or provide for the exclusive use of a frequency.

You have some leverage if you are the incumbent or earliest licensed user of a frequency. Usually any FCC restrictions or modifications in an interference case that fails to resolve by mutual cooperation are imposed on the newcomer.

I suspected if it came down to it there would be a decision based on "who was there first", in that case it appears it may be on us to move.

It really looks like this may be on a coordinator we used a while back... it shows the other user getting the frequency in 2013 and looks like we got it in 2016. When I took over last year and was trying to clean things up a bit I approached another coordinator who modified our license, so I could see how to them there would be nothing of concern with that frequency as it had been on the license without incident for seven years. Little did they know that the repeater power was unplugged at some point (not kidding, found it that way in an equipment closet), and nobody even set their HTs past about channel 5 (repeater is on 16), so there was rarely anyone using it on our end to notice.

Ah the joys of working in the public sector, they "needed" the repeater so much years ago that they forgot they even had it let alone tried to use it.

 

[jackw414]

That change would cost a lot of money, and no one is going to want to do that.

I recall a time when a good quantity of wireless microphone and in ear monitor systems got caught in the FCC's crosshairs years back and were no longer usable, I spent some time working in live sound and still do on occasion. People had a fit over the change, I can only imagine what it would be like to force people to change on something with a wider impact.

 

[mmckenna]

Ah the joys of working in the public sector, they "needed" the repeater so much years ago that they forgot they even had it let alone tried to use it.

Them abandoning the repeater for so long sort of gives up any claim they have to the frequency. When licensing a channel, there's usually a one year clock that starts where the licensee has to file with the FCC saying the channel is actively in use. If the licensee fails to do that, or stops using the channel for a long time, it's sort of an abandonment and a frequency coordinator could reuse it.

I had that happen about 25 years ago when I took over our radio systems. Found we had a really good repeater pair on VHF that had been forgotten about. Went about the steps to put it back in service only to find the adjacent county had found it and licensed it for their fire department.

People had a fit over the change, I can only imagine what it would be like to force people to change on something with a wider impact.

There would be many tantrums thrown, as well as those that would just refuse to change and screw it up for everyone else.

In a way, I'm glad to see more and more non-public safety two way radio users move to cellular. Give me a bit of hope that at some point in the future the bands can be cleaned up for those that actually need it.

 

[alcahuete]

There are currently 4 or 5 others that overlap with one of my IG frequency assignments. We were the 2nd ones to get coordinated on that frequency, and our coordinator obtained permission from the other coordinator for our co-use of the frequency. No interference to or from them at all. As a good steward of the bandwidth, I actually reached out to their business and did some testing.

The other ones popped up years later, one as recently as last year. I will pretty regularly hear a couple of them on analog if I run CSQ, but we just keep blasting away our encrypted digital at 200W ERP, without a care in the world. Certainly no interference to our system.

 

[cavmedic]

I have 7 IG pairs and every single one of them have multiple co-channel users licensed on them within a few miles. The latest pair is about one air mile from another user. When submitting coordination, they do say that that the frequencies are shared.

It works out most of the time being 3 sites are IPSC and the users who roam are limited. Two other sites are simulcast with different users than the first system.

The closer you get to urban areas, the more you will find co-channel.

 

[N4DES]

I licensed my HOA to a low power/low altitude UHF pair and not long after putting it on the air we received constant interference from another licensee that had just the input frequency for an irrigation system that was operating outside of its licensed parameters and with no call sign. After I did some research and direction finding I presented the findings to the coordinator, and they reached out to the other licensee. After some bickering from the other party the coordinator got the FCC involved and they wrote a pretty stern letter to the other licensee and golf course management company. In the end the other party brought their system into compliance about 4 months after the FCC letter was generated and my HOA's repeater hasn't heard them since.

 

[prcguy]

The information a frequency coordinator uses to help you choose a frequency for licensing is not always realistic and some users of that frequency may be long gone or may have increase their operations beyond their limits. When I owned a repeater business I used a RS Pro 2004 scanner with a PL/DPL decoder and computer logger to capture what tones are used and for how long, giving me a real picture of channel usage.

It would take about a month to monitor a group of frequencies one at a time choose the one with the lowest use and request licensing on that frequency from my coordinator. Pretty much all of the coordinator recommend frequencies were hogged by big time users and my method gave me some pretty quiet channels at that time.

 

[freddaniel]

I second what prcguy suggests. Be aware coordinators have only the FCC database to work with. They have no way to know of users who use excess airtime or even if they are on the air, at all. Also, there are a significant number of users who continue to operate with expired licenses and fall off the FCC database.
This type of real-world on-the-air survey is always best, before requesting coordination. Local radio shops who do this always have happy customers. In urban areas with lots of co-channel users, repeaters with voting receivers can overcome co-channel interference on the input.

 

[ecps92]

Hello All,

We are currently licensed for a set of frequencies but in searching the ULS I am noticing some oddities around proximity to others on the same frequencies.

Take for example a FB2 we have with the following:


The reason I ask is that as I sit with 3 HTs in front of me on that repeater (and within our radius around the repeater, quite close to it actually) something is transmitting on the RX frequency of the HTs (the TX for our repeater).

I.

Again just not sure and would hate to potentially insult our coordinator by asking the question, but this seemed possibly problematic to me.

Thanks,
Jack

Your noted "something is transmitting" - have your dropped PL/DPL and actually heard Voice or Telemetry ?
or might this be something local causing interference, such as a computer, cable box, monitor, Microwave, Fridge etc ??

 

[speedway_navigator]

Also, many of the current frequencies were set up for the older 5KHz deviation radios, so there's now a lot of wasted space in the gaps. If entire bands could be refarmed into closer channel spacing, it would make life easier.

I wonder if some time in our future we might see the FCC encourage (or require) trunking on a multi user scale between different systems to get away from the 'stove pipe' system now where each user licenses a set of freqs.
I'm talking about roaming from Joe's DMR to Bob's system even though they might be competitors renting airtime, or single user systems tying together to share freqs.

This wasn't possible until IP linking came along

 

[mmckenna]

I wonder if some time in our future we might see the FCC encourage (or require) trunking on a multi user scale between different systems to get away from the 'stove pipe' system now where each user licenses a set of freqs.
I'm talking about roaming from Joe's DMR to Bob's system even though they might be competitors renting airtime, or single user systems tying together to share freqs.

This wasn't possible until IP linking came along

Kind of like roaming on cellular.

I think the FCC would like it if many business users migrated to LTE.

 

[AM909]

The problem is that it relies on both Joe and Bob to know what they're doing and build and maintain their systems well. Say what you like, but that's a lot more likely for big cellular carriers than Joe's Two-Way Shop.

 

[Echo4Thirty]

Cellular companies do it because they get paid from their competitors. They dont do it out of the kindnes of their hearts. Its also why you see carriers impose limits to roaming in their TOS and will boot a subscriber for excessive roaming. The odds of getting Joe to pay Bob the fees for when his users roam over is next to nil.

I would bet paychecks you would never see the FCC attempt to tell business radio carriers they have to allow roaming between systems. For that matter Id extend that to part 90 public safety systems. While PS systems often connect to each other, they did it on their own without an FCC mandate.

As someone who managed a few for profit business SMR systems in my past, i cant see any owners allowing their systems to be connected to a competitor any more than Burger King selling a Big Mac because someone at the FDA chose to create a mandate.

 

[N4DES]

The FCC provides annual benchmarks to Congress that justifies their existence and license grants is included as one of them. I doubt that they would look to eliminate individual frequency issuance anytime soon.