902
Member
This wouldn't happen to be the system that's licensed to the wrong coordinates from the industry discussion thread, is it?
158.9400 Interference
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This is the same system. I know many people may say that this is the cause of the problem. However regardless of whether the coordinates are right or wrong our systems have been in operation where they currently exist for over 12 years. Why would we now be experiencing problems? With that being said I still would like to get our coordinates updated.
Cheers,
Brandon
Cheers,
Brandon
902
Member
By all means.
The first thing you need to do is complete a Form 601 as a "Modification" listing the proper coordinates (X-Y-Z), HAGL, ERP, and HAAT information. Then send that to a public safety frequency coordinator of your choice. The person northwest of you, whom you spoke with, could probably help you. Make sure it's right before you press the send button on whatever software or website you choose. Both your PS frequency output and PX frequency input will need to be recoordinated. The input because the point coordinate on which it is centered has moved. It may be necessary to reduce your 80 km area of operation (the ski lodge seems to be less than 50 miles in all directions).
That's step 1.
Are you sure you've positively identified that system as the culprit? Yes, it's on a mountain and has an astronomical footprint for the area it attempts to cover (just like yours), but a road trip, or at least further communication with the other party might be in order to confirm.
The other question to ask, since your system predates your involvement and is 12 years old, and the other system has had a high-ERP simplex base for 30 years and a lower power repeater for 4 years, what changed? Have you always been receiving this interference, or did it start now? Is it always there, or do you notice it only during incidences of tropospheric ducting?
Your problem is not unique. It's fairly common in the Rockies, where systems seem to be placed on the mountain top or face to cover the valley immediately below. The better your system works, the more it will pull in for miles. Also, stock antenna configurations will send your signal into another state (or states) - exactly where you don't need the coverage. You may want to investigate an electrical downtilt antenna that has characteristics that saturate downward coverage, rather than outward coverage, or a unity gain antenna that would have a very large vertical beamwidth and direct less signal outward toward the horizon and more downward into the intended area. You also seem to have a lot of terrain blocking. Employing an electrical downtilt would be advantageous to your close-in operations and would cut down on diffraction well outside your area. Also a different CTCSS tone, but considering the potential for ducting and the use of a fairly common frequency, using a CDCSS code. The same might apply for them (except a different CDCSS from yours). The alternative is looking for another frequency, and mountaintop VHF is no plum. You essentially trade one set of problems for a yet-to-be-discovered other set of problems.
I also have a feeling that 90.205 Safe Harbor may come into play here.
Just stuff to think about.
902 you offer a lot of great suggestions and advice. I greatly appreciate your reply, time, and help!
We definitely intend on updating our GPS Coordinates for our repeater. However we want to do this at the right time and I am not sure if right now is the right timing. I have read some information that suggests if your physical address of the repeater is accurate then updating the GPS coordinates is not as difficult. Since I am not a frequency coordinator I can only assume that they use the GPS coordinates of transceivers instead of physical addresses for coordination purposes therefore suggesting to me an accurate physical address isn't going to help or gain us a whole lot.
I have positively identified the "culprit." I have been in contact with them directly and I have provided them with video recordings of the interference we have been picking up. They have confirmed that their repeater output is operating on the same frequency as our repeater input. They are utilizing the same CTCSS Tone that I decoded with the interfering signal further suggesting they are the source. They are also using the Kenwood Fleetsync system which is easily detected on all the interfering signals we have been receiving.
I am not sure what has changed. We have not experienced this interference in the past and I have been heavily involved in our communications system for the past 7 years. The high-ERP simplex base is reported to be offline. This means the source of the interference is the lower power repeater. They use their repeater for their Public Works Department and coordinating trucks and snow plows. They have had a lot more snow in their area this year which has increased the amount of radio traffic. Our systems are operating on different CTCSS Tones so we only notice the interference when our repeaters receiver is successfully opened up with the correct tone. At that point the receiver picking up any carrier on that frequency for as long as the correct tone is keeping the receiver open. We have been keeping a log of the interference and we only notice it from about 6am-1pm Monday-Friday however during that time there is A LOT of traffic on that frequency. We haven't noticed any issues on the weekends or holidays. Weather and atmospheric conditions do not seem to play any role or factor in the interference.
The radio techs for Kootenai County volunteered to go check on their repeater and make sure it was operating within specifications and the parameters of their license. They performed this task last week and advised that everything checked out fine. They confirmed the repeater was transmitting at 20watts with an ERP of 15. They even went as far as to decreased the power of their repeater to 10watts bringing their ERP down to 7.5. We have noticed a change in the level of interference however it is still present. They are going to leave their repeater at the lower transmit power for a couple weeks to see if they notice any significant change or problems with their coverage area. They told me that they have been operating with a low gain antenna with some down tilt.
Even if they are able to continue operating at the lower wattage output I am not sure if we can continue to operate with the level of interference we are still experiencing. Given that we will have to update our license to reflect the actual GPS coordinates of our repeater and go through the frequency coordination process anyway we may look into getting a different input frequency. Right now we are operating with a StationMaster High Gain Omnidirectional type antenna. We don't need the 80km radius however we do need to talk outside of the resort as we are responsible for maintaining the Forest Service road and communicating back to our Downtown Office.
Needless to say there are a lot of variables and lots to consider as we move forward.
We definitely intend on updating our GPS Coordinates for our repeater. However we want to do this at the right time and I am not sure if right now is the right timing. I have read some information that suggests if your physical address of the repeater is accurate then updating the GPS coordinates is not as difficult. Since I am not a frequency coordinator I can only assume that they use the GPS coordinates of transceivers instead of physical addresses for coordination purposes therefore suggesting to me an accurate physical address isn't going to help or gain us a whole lot.
I have positively identified the "culprit." I have been in contact with them directly and I have provided them with video recordings of the interference we have been picking up. They have confirmed that their repeater output is operating on the same frequency as our repeater input. They are utilizing the same CTCSS Tone that I decoded with the interfering signal further suggesting they are the source. They are also using the Kenwood Fleetsync system which is easily detected on all the interfering signals we have been receiving.
I am not sure what has changed. We have not experienced this interference in the past and I have been heavily involved in our communications system for the past 7 years. The high-ERP simplex base is reported to be offline. This means the source of the interference is the lower power repeater. They use their repeater for their Public Works Department and coordinating trucks and snow plows. They have had a lot more snow in their area this year which has increased the amount of radio traffic. Our systems are operating on different CTCSS Tones so we only notice the interference when our repeaters receiver is successfully opened up with the correct tone. At that point the receiver picking up any carrier on that frequency for as long as the correct tone is keeping the receiver open. We have been keeping a log of the interference and we only notice it from about 6am-1pm Monday-Friday however during that time there is A LOT of traffic on that frequency. We haven't noticed any issues on the weekends or holidays. Weather and atmospheric conditions do not seem to play any role or factor in the interference.
The radio techs for Kootenai County volunteered to go check on their repeater and make sure it was operating within specifications and the parameters of their license. They performed this task last week and advised that everything checked out fine. They confirmed the repeater was transmitting at 20watts with an ERP of 15. They even went as far as to decreased the power of their repeater to 10watts bringing their ERP down to 7.5. We have noticed a change in the level of interference however it is still present. They are going to leave their repeater at the lower transmit power for a couple weeks to see if they notice any significant change or problems with their coverage area. They told me that they have been operating with a low gain antenna with some down tilt.
Even if they are able to continue operating at the lower wattage output I am not sure if we can continue to operate with the level of interference we are still experiencing. Given that we will have to update our license to reflect the actual GPS coordinates of our repeater and go through the frequency coordination process anyway we may look into getting a different input frequency. Right now we are operating with a StationMaster High Gain Omnidirectional type antenna. We don't need the 80km radius however we do need to talk outside of the resort as we are responsible for maintaining the Forest Service road and communicating back to our Downtown Office.
Needless to say there are a lot of variables and lots to consider as we move forward.
12dbsinad
Member
- Joined
- Mar 15, 2010
- Messages
- 2,005
You mention that this low power repeater is used by Public Works. It's odd that this isn't used more often than the hours you indicate. I know in my area if it's snowing and crews are out, the Public Works channel is active no matter the time of day, weekends, etc.
On a positive note, at least they are willing to work with you on this. That's a good thing.
On a positive note, at least they are willing to work with you on this. That's a good thing.
902
Member
Brandon,
The PD-220 might have a 3 or 6 degree electrical downtilt, but it's not a stock item, so unless you know for sure, you'd be okay presuming most of the signal is directed to the horizon. Using DT will reduce your susceptibility to Kootenai - or anywhere else far away while looking down the mountain and concentrating signal there. It would probably improve your local coverage, too. Interference is a locational issue when you're on a mountaintop (and sometimes you have ducting which is a completely different issue). Any frequency you choose will more than likely have something on or immediately adjacent to it that you'll have to mitigate, and that could be exacerbated by the HAAT values on either end.
You probably should consider correcting your license right now. The Commission looks at a situs address or description for access, but when determining the power levels received, or if they have to use the site in resolving a dispute (not all interference cases cooperate), they look solely on the licensed parameters provided. Each of the coordinators goes solely on coordinates. In general, a move of less than 5 arc-seconds latitude or longitude (the distance in km differs based on where on the world you are), AMSL height of no greater than 2m, and no increase in ERP is considered a "de minimis" move in terms of coordination (you still have to modify the license with the correct data), but exceeding those values requires full coordination. There is some consideration given to stations already on the air, but that can't be guaranteed if they are fairly far off. As for reconciling coordinates to a situs address, a preparer, processor, or advisor may catch that, but your mileage may vary. Many presume the applicant has provided accurate information (and the applicant signs that they did on the main form - ultimately it's their responsibility). Sometimes another coordinator catches it during the "notification" process, and sometimes (but not always) it's corrected.
As far as changes, maybe it's always been there but your use has picked up and it's now noticeable, or maybe your predecessors didn't pick up on it or know what to do with it. Either way, if they're direct line of sight to you (which seems to be the case in at least one of their sites, the other one kind of diffracts over some peaks), you reach the point of diminishing returns with their power reduction.
Like I said earlier, feel free to PM or email me (email may work better, as my message folder is cluttered and usually maxed out) and we can continue this offline.
The PD-220 might have a 3 or 6 degree electrical downtilt, but it's not a stock item, so unless you know for sure, you'd be okay presuming most of the signal is directed to the horizon. Using DT will reduce your susceptibility to Kootenai - or anywhere else far away while looking down the mountain and concentrating signal there. It would probably improve your local coverage, too. Interference is a locational issue when you're on a mountaintop (and sometimes you have ducting which is a completely different issue). Any frequency you choose will more than likely have something on or immediately adjacent to it that you'll have to mitigate, and that could be exacerbated by the HAAT values on either end.
You probably should consider correcting your license right now. The Commission looks at a situs address or description for access, but when determining the power levels received, or if they have to use the site in resolving a dispute (not all interference cases cooperate), they look solely on the licensed parameters provided. Each of the coordinators goes solely on coordinates. In general, a move of less than 5 arc-seconds latitude or longitude (the distance in km differs based on where on the world you are), AMSL height of no greater than 2m, and no increase in ERP is considered a "de minimis" move in terms of coordination (you still have to modify the license with the correct data), but exceeding those values requires full coordination. There is some consideration given to stations already on the air, but that can't be guaranteed if they are fairly far off. As for reconciling coordinates to a situs address, a preparer, processor, or advisor may catch that, but your mileage may vary. Many presume the applicant has provided accurate information (and the applicant signs that they did on the main form - ultimately it's their responsibility). Sometimes another coordinator catches it during the "notification" process, and sometimes (but not always) it's corrected.
As far as changes, maybe it's always been there but your use has picked up and it's now noticeable, or maybe your predecessors didn't pick up on it or know what to do with it. Either way, if they're direct line of sight to you (which seems to be the case in at least one of their sites, the other one kind of diffracts over some peaks), you reach the point of diminishing returns with their power reduction.
Like I said earlier, feel free to PM or email me (email may work better, as my message folder is cluttered and usually maxed out) and we can continue this offline.
For those of you who have been following this interference discussion I have some new videos and pictures that you may be interested in. I also have some updated information that I can share with you.
We are still experiencing interference with Kootenai County (ULS License - Public Safety Pool, Conventional License - WNHR372 - KOOTENAI, COUNTY OF). I guess to be more accurate it is not necessarily interference since we are both licensed to use this frequency. Our repeater is just receiving competing signals. Kootenai County voluntarily decreased their power output of their repeater last week to 10watts with an ERP of 7.5. The YouTube video links that I have shared in this post were taken today and show the strength of the signal we are receiving even with the decreased power output of their system. The video obviously shows that I am using a handheld VX150 with a 3" rubber duck antenna for my testing purposes. If my handheld is picking up the Kootenai County repeater which is located about 120mi North of us then I can only imagine what the repeater is receiving with the high gain base station antenna. As compared to my previous videos I did notice a slight decrease in the strength of the signal we are picking up from Kootenai County and we have noticed the distortion is not as frequent or severe. However the distortion is still frequent enough and severe enough that I am not sure we can tolerate it even if they can continue operating at a reduced ERP.
Here is a picture of our repeater site: Panoramio - Photo explorer
Here are the YouTube Videos from today:
https://youtu.be/smJM7CGX-dU
https://youtu.be/AT3Y_aMRmaA
https://youtu.be/u2BGSNLQALI
We are still experiencing interference with Kootenai County (ULS License - Public Safety Pool, Conventional License - WNHR372 - KOOTENAI, COUNTY OF). I guess to be more accurate it is not necessarily interference since we are both licensed to use this frequency. Our repeater is just receiving competing signals. Kootenai County voluntarily decreased their power output of their repeater last week to 10watts with an ERP of 7.5. The YouTube video links that I have shared in this post were taken today and show the strength of the signal we are receiving even with the decreased power output of their system. The video obviously shows that I am using a handheld VX150 with a 3" rubber duck antenna for my testing purposes. If my handheld is picking up the Kootenai County repeater which is located about 120mi North of us then I can only imagine what the repeater is receiving with the high gain base station antenna. As compared to my previous videos I did notice a slight decrease in the strength of the signal we are picking up from Kootenai County and we have noticed the distortion is not as frequent or severe. However the distortion is still frequent enough and severe enough that I am not sure we can tolerate it even if they can continue operating at a reduced ERP.
Here is a picture of our repeater site: Panoramio - Photo explorer
Here are the YouTube Videos from today:
https://youtu.be/smJM7CGX-dU
https://youtu.be/AT3Y_aMRmaA
https://youtu.be/u2BGSNLQALI
jrw14493
Member
- Joined
- Dec 30, 2003
- Messages
- 69
It appears that Ski Bluewood is a private entity?
If I were you, I'd go get new frequencies in the 90.35 which is a lot less congested than the 90.20. You'll need to re-tune the duplexer and reprogram everything but it's a lot better than dealing with interference you can't do anything about.
And not that it matters but Kootenai County has a build out date of 1986, about 18 years before your input freq was constructed. They were there first. I'd get the money back from your coordinator...
If I were you, I'd go get new frequencies in the 90.35 which is a lot less congested than the 90.20. You'll need to re-tune the duplexer and reprogram everything but it's a lot better than dealing with interference you can't do anything about.
And not that it matters but Kootenai County has a build out date of 1986, about 18 years before your input freq was constructed. They were there first. I'd get the money back from your coordinator...
jtstockton
Member
- Joined
- Aug 7, 2011
- Messages
- 4
I know I am a little late to the party...
I am in Kootenai county, about 7 miles from the repeater site. If I can help in any way, let me know.
Justin
I am in Kootenai county, about 7 miles from the repeater site. If I can help in any way, let me know.
Justin
jtstockton
Member
- Joined
- Aug 7, 2011
- Messages
- 4
I set up a vox recorder to listen to 158.9400 today, I will give it a listen tonight and report back. It's been a while since I have been up to the site (it's a fairly busy site) I will see what I can dig up for you.
If you like, I can setup a live stream so you can listen from my side and compare to what you are hearing
If you like, I can setup a live stream so you can listen from my side and compare to what you are hearing
jtstockton
Member
- Joined
- Aug 7, 2011
- Messages
- 4
I had a chance to review the recordings this evening.
From what I can determine, there is a CW broadcast 15-16 minutes after the hour -
CW Audio - https://db.tt/1LL6jxlS
If I remember my CW this translates to "KJG991" According to ULS belongs to The City of Post Falls, but I dont see a license for that freq
ULS License - Public Safety Pool, Conventional License - KJG991 - POST FALLS, CITY OF - Frequencies Summary the site is on Blossom Mtn which is a few miles NE of Mica.
Here is a small sample of the audio collected today, keep in mind that the recorder removes dead air so the time is compressed -
https://db.tt/PrE0ecOO
Not sure if any of this helps at all?
Cheers,
Justin
From what I can determine, there is a CW broadcast 15-16 minutes after the hour -
CW Audio - https://db.tt/1LL6jxlS
If I remember my CW this translates to "KJG991" According to ULS belongs to The City of Post Falls, but I dont see a license for that freq
ULS License - Public Safety Pool, Conventional License - KJG991 - POST FALLS, CITY OF - Frequencies Summary the site is on Blossom Mtn which is a few miles NE of Mica.
Here is a small sample of the audio collected today, keep in mind that the recorder removes dead air so the time is compressed -
https://db.tt/PrE0ecOO
Not sure if any of this helps at all?
Cheers,
Justin
I had a chance to review the recordings this evening.
From what I can determine, there is a CW broadcast 15-16 minutes after the hour -
CW Audio - https://db.tt/1LL6jxlS
If I remember my CW this translates to "KJG991" According to ULS belongs to The City of Post Falls, but I dont see a license for that freq
ULS License - Public Safety Pool, Conventional License - KJG991 - POST FALLS, CITY OF - Frequencies Summary the site is on Blossom Mtn which is a few miles NE of Mica.
Here is a small sample of the audio collected today, keep in mind that the recorder removes dead air so the time is compressed -
https://db.tt/PrE0ecOO
Not sure if any of this helps at all?
Cheers,
Justin
Thanks for all your help. I will include this in my documentation. It sounds consistent with the co-channel interference that we are experiencing.
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