Interference between two agencies - how to get it resolved

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TomServo

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OK, I'm just a listener, but I am really tired of the interference problems my local PD (Grenada city) is suffering. It seems that the Yalobusha County Sheriff's department's repeater output is on the city of Grenada's repeater input. This causes problems on a fairly regular basis because the city of Grenada is only about 13 miles from one of the repeaters for the Yalobusha County system. I listen most nights to the Grenada repeater input and the Yalobusha system is strong enough to overwhelm some of the more distant patrol cars here in my city.

I want to get this situation resolved because it seems to cause some consternation amongst some of the city police here but no one has done anything about it in the three years I've been residing in Grenada.

Is there someone I can contact to get the ball rolling to get one of the frequencies changed to something else?

Grenada's PD input is 159.150, and Yalobusha's dispatch output is 159.1575. I don't have a radio capable of differentiating that channel spacing but even if I did the Yalobusha signal is wide and spreads well over onto the adjacent channel.

Is there a solution to this mess or am I, like the local PD, at the mercy of the interference?
 
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N_Jay

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Other then you asking them if they want you help, it is not your issue.

It is the right and responsibility of the LICENSEES who is being interfered with to make any complaints to the FCC, the coordinators, and/or the other licensee.

Your responsibilities are clearly explained on the Part 15 notice either attached to your radio or included in the instruction manual.
 

iamhere300

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The FCC - nor the APCO interference folks will not even accept your complaint as stated. If the licensee feels it is an issue, they SHOULD know how to resolve it.
 

Deeke

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Try using a less sensitive antennae. You will one or the other or try the attenuator on one.

Your in the twilight zone between the two i assume. You may not be able to have both w/o interference.
 

TomServo

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It's not a problem with my reception, it's a problem with interference on the local PD's end. Next time I talk to one of them I'll ask if anyone even knows how to get in touch with a local coordinator. Judging by some of the frequencies I find them on, I'm not even sure they know how to apply for a license with the FCC at all. ;)
 

kc2rgw

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If you don't hear them complaining, it's likely your receiver.....

I wouldn't touch that hornets nest with a 10 foot pole. Their radio guys would take care of it if there were a problem.

Public safety equipment...and current Uniden and other scanners have PL enabled or DCS...I would bet they don't hear it on their systems.
 
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TomServo

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If you don't hear them complaining, it's likely your receiver.....

I wouldn't touch that hornets nest with a 10 foot pole. Their radio guys would take care of it if there were a problem.

Public safety equipment...and current Uniden and other scanners have PL enabled or DCS...I would bet they don't hear it on their systems.
Oh no, I hear them complaining. "10-9, your radio is cutting out" is probably the thing I hear most on there at night, lol. Anyway if I listen to Grenada's repeater output I still hear the interference, so I dunno why anyone would think it was my radio. :confused:

They don't hear the other system since the PL codes are different, but if the Yalobusha repeater is keyed and one of the officers keys up the repeater outputs a mishmash of noise and everything's unintelligible.

If I can pick up the Yalobusha system on the ground, in a house, with a modest antenna, I'm sure their repeater up on top of the hill outside town is getting quite a strong signal.

Guess I'll just keep my mouth shut on the issue and if it causes some cop problems on the beat, well it ain't my problem. Just thought it might be easier to contact someone else about the problem in case the city doesn't know/understand that it can be fixed.
 

kc2rgw

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Very weird, those sort of conflicts are generally fixed right away. They must have lousy radio guys.

I'd still say, stay out of it. The towns/staff get really funny when it is brought to light that people are listening enough to notice things like this. Unless you know people well inside the town, then maybe that would be o.k.

The reason I mentioned your receiver is pretty simple.

If you are in the middle of co-channel stations you can have both signals vying for capture in your receiver, In the field with LMR equipment, they very well may not hear it on their system. You *could* have been hearing another co-channel station on that output that they might never notice with their gear.

Two sides to it with scanners. The receivers are not as selective as LMR equipment and often we have the squelch thresholds at about half what an LMR radio is programmed for. You can hear nearby adjacent signals as noise overlayed on the frequency you are monitoring etc. The other side is, that serious enthusiasts can actually have a better antenna configuration than some of the towns' equipment. Both can cause you to hear things that they wouldn't within their system.

The fact they are complaining on the air about it though confirms the interference....and again, I'm very surprised that it is going on It has to be a pretty strong signal to cause that much disruption.....I'm amazed they haven't fixed that.
 
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N_Jay

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They are 7.5 kHz apart.
That is not enough, but VHF frequency coordination is a mess everywhere.
They may be resisting spending anything on the old system hoping for a new one.

You can always try attending a "Public Safety Commission" (or similar) meeting (sitting quietly) to learn a little more about what is going on.

Just remember a good analogy is;
it is like you are a passer-by looking through their living room window, and feel like you want to help them settle a family disagreement. (you may be right, but most often your "intrusion" is not appreciated.)
 

radioman2001

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As far a fixing the problem for you, not likely. APCO is supposed to do an interference contour study on each application. I know because I am constantly fighting with them. Sounds like they dropped the ball big time on this one, OR the 7.5 kc away offending agency is doing the following, too much power out, above and beyond their license. Too much gain in their antenna, or their station is not located where they said it is. The other side is that the recipient of the interference station receiver is not narrow banded yet, and is locking on to the offending station. While they are not mandated to switch yet, I suspect they will not until the 01-01-2013 deadline or until some one gets killed as a result of the interference. The local radios shops can sometimes be more of a liabilty than an asset with these types of complaints. I suggest if you know someone in the department, just let them know they can have the problem resolved, but they need to file complaints with the FCC and APCO, and wait a long time for action. I suspect that APCO is waiting for the deadline to make the complaint moot.
 

milf

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Or its this- one agency has newer equipment already set up for narrowband operation on 7.5 or tighter spacing, and the other is using older wideband equipment. The interference issues can be solved by one of two methods by the agency that has issues... 1- Change the tone on input to block out the interference. 2- Upgrade to narrowband equipment. Or better yet, do both. Many agencies purchased newer gear to comply with the OLD narrowband ready requirement by 2013. Many others have not made the transition as of yet. Since the new date for compliance for both narrowband, AND digital readiness is now 2020 this will make it easier on the money strapped agencies, but will cause issues with those agencies that are being last minute lax on it.
 

TomServo

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Thanks for the continued input. I'll definitely stay out of it unless I wind up talking to someone who's more familiar with their setup than the beat guys. It does sound like maybe my town's repeater isn't yet set up for narrowband and that's why it's snagging those unwanted signals.

The two agencies do use different PL codes but of course that only keeps the repeater here from keying. The signal is still present though which of course causes the interference when both agencies are active.

Maybe it's just lately that Yalobusha has been more active at night, or atmospheric conditions are affecting things, but tonight there were no problems that I heard.

I can definitely understand cost being an issue, as well as them not wanting to know who's listening, so I'll just let it be. I just thought it might be possible for them to switch from the current repeater input to one of their other licensed frequencies, since they are all apparently programmed into the existing radios (they have two other simplex channels for car-to-car chatter, one in the license list and one not, I think.)

If nothing else, listening to public safety agencies in Mississippi has been an eye opener. I came from the Birmingham area where most of the systems (at the time) were on UHF, except for the smaller suburbs, and it wasn't unusual for me to grab those signals from 40 or more miles out with nothing more than a 5/8 wave mag mount on a car. Everyone just about got out real well. Here some agencies seem to barely cover their own towns, but at the same time I regularly hear Bolivar, Cleveland and Oxford stuff just fine with an antenna inside the house!

Oh well, live and learn. ;)
 

jim202

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I would say that the site your hearing is at 80 County Rd 437 in Water Valley, MS. The license is
WPQF602 issued 05-12-2005 and expires 06-26-2015.

This is much further than the 13 miles your talking about from their nearest site.

My thoughts are that the city of Genada needs to modify their repeater receiver to be a narrow band receiver
and the problem should be reduced if not eliminated. However, and I say this carefully, if the Yalobusha
County repeater is not running narrow band deviation, then they may be adding to the problem.

One good point to consider, that by January of 2013, this all should be moot. All the VHF radios
that are currently in service now will have to be switched over to narrow band operation anyway.
This means that all the repeaters, mobiles and portables now being used, will have to either be
replaced or reprogrammed to only transmit narrow deviation. Many of the radios that are old, can
not be made to function on the narrow band deviation mandate by the FCC and will have to be
replaced. If the equipment is new and only purchased in the last few years, it all ready is able
to go the narrow band. The radio shop will just have to reprogram them for the narrow mode.

As for the scanner people out there, you will have to turn up the volume control and put up with
the adjacent channel issues. I am not aware of any scanner out today that has been made to
do the narrow band channel deviation. I could be wrong, but for the majority of scanners out
in the hands of the listeners, this may become a problem.

Jim




OK, I'm just a listener, but I am really tired of the interference problems my local PD (Grenada city) is suffering. It seems that the Yalobusha County Sheriff's department's repeater output is on the city of Grenada's repeater input. This causes problems on a fairly regular basis because the city of Grenada is only about 13 miles from one of the repeaters for the Yalobusha County system. I listen most nights to the Grenada repeater input and the Yalobusha system is strong enough to overwhelm some of the more distant patrol cars here in my city.

I want to get this situation resolved because it seems to cause some consternation amongst some of the city police here but no one has done anything about it in the three years I've been residing in Grenada.

Is there someone I can contact to get the ball rolling to get one of the frequencies changed to something else?

Grenada's PD input is 159.150, and Yalobusha's dispatch output is 159.1575. I don't have a radio capable of differentiating that channel spacing but even if I did the Yalobusha signal is wide and spreads well over onto the adjacent channel.

Is there a solution to this mess or am I, like the local PD, at the mercy of the interference?
 

milf

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Again I must state the deadline has been switched. The old 2013 date has been moved to January 2020 for ALL agencies nationwide to switch to radios capable of narrowband operations and capable of digital operation. This includes ALL Public Safety, as well as Railroads. The FCC made this change about a month ago. I can't say for sure if the Federal deadline has been pushed back also, but the non fed systems must be operational in narrowband and capable of digital by 2020. The old deadlines were phase I narrowband by 2013, phase II narrowband by 2017. The Phase II (6.25 Khz) of course will require digital operation. At this time about half of the state of MS has already complied with the Phase I requirements in order to be ready by 2013, the OLD deadline. The following reasons are why this deadline was changed- 1: Not all radios on the market are fully compliant for both phases yet, though all the newest production models are Phase I compliant. 2: There are still MANY agencies nationwide that have not been able to afford to change out all their gear. Another little bit of information... This one is obvious- Bye Bye VHF Lo Band as of 2020.

Most current production scanners are fully narrowband capable for Phase I, and the newest can do Phase II narrowband. So you should not have any issues in that respect. The only thing that current scanners can't do is APCO P-25 Phase II digital. This may change by the time 2017-2020 rolls around and the mandate for switching to P-25 Phase II takes place.
 
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GTR8000

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Again I must state the deadline has been switched. The old 2013 date has been moved to January 2020 for ALL agencies nationwide to switch to radios capable of narrowband operations and capable of digital operation. This includes ALL Public Safety, as well as Railroads. The FCC made this change about a month ago. I can't say for sure if the Federal deadline has been pushed back also, but the non fed systems must be operational in narrowband and capable of digital by 2020. The old deadlines were phase I narrowband by 2013, phase II narrowband by 2017. The Phase II (6.25 Khz) of course will require digital operation. At this time about half of the state of MS has already complied with the Phase I requirements in order to be ready by 2013, the OLD deadline. The following reasons are why this deadline was changed- 1: Not all radios on the market are fully compliant for both phases yet, though all the newest production models are Phase I compliant. 2: There are still MANY agencies nationwide that have not been able to afford to change out all their gear. Another little bit of information... This one is obvious- Bye Bye VHF Lo Band as of 2020.

Most current production scanners are fully narrowband capable for Phase I, and the newest can do Phase II narrowband. So you should not have any issues in that respect. The only thing that current scanners can't do is APCO P-25 Phase II digital. This may change by the time 2017-2020 rolls around and the mandate for switching to P-25 Phase II takes place.
Please post links to reputable sources to back up your claims here. I have heard and seen nothing to suggest that the deadline for 12.5 kHz narrowbanding has changed from 2013. Where are you getting this "2020" date from? Also, narrowbanding only affects frequencies between 150 - 512 MHz, so the claim about VHF Low going "bye bye" is questionable as well.
 
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jim202

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I too am about as close to this issue as any other tech person and have not seen anything official released
about any date change. Please provide a link of your source from the FCC with their official release.

Jim




Please post links to reputable sources to back up your claims here. I have heard and seen nothing to suggest that the deadline for 12.5 kHz narrowbanding has changed from 2013. Where are you getting this "2020" date from? Also, narrowbanding only affects frequencies between 150 - 512 MHz, so the claim about VHF Low going "bye bye" is questionable as well.
 

milf

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I got this information from techs with the Arkansas State Department of Information Services (DIS) They were discussing various aspects of implementation on the AWIN, and mentioned that some things should be easier now that the narrowband/digital deadline was moved to 2020 by the FCC. This same conversation was also how I gathered information about the implementation of a statewide MED Net on the AWIN. This information was also repeated on the air during testing of a TG on the AWIN. Remember 12.5 is just the first step that would only last 4 years according to the original planning. In 2017 implementation of 6.25 spacing is required by the old deadline. According to ARDIS techs, the moving of the entire plan to 2020 allows for everyone to purchase, program, and install gear capable of both 12.5, and the fully digital 6.25 spacing requirements.
 

GTR8000

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Well, either those techs were mistaken, or you misinterpreted what they were saying. The narrowbanding deadline has not been altered, it stands at 2013 to move to 12.5 kHz. There was never a firm, official deadline for 6.25 kHz, the 2017 date was just industry speculation. It sounds like there is some confusion on their part or your part between the similar but unrelated narrowbanding issue versus the P25 Phase II issue.
 

milf

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6.25 spacing will be digital only. There is no other way for it to work. APCO-P-25 Phase II is the switch to TDMA digital, and is a separate issue. Phase II of narrowbanding is the switch to 6.25 KHz from 12.5 Khz spacing in VHF Hi. The DIS tech told the entire AR Hospital Ass'n, State EMS admin, and all others monitoring the date was moved to 2020 on air as well as at the meeting. So if he was mistaken, then there are a lot of folks that are in for surprises if this country is still in one piece in 2013.

The good thing is that all currently manufactured radios, as well as scanners are fully 12.5, and 6.25 capable. The remaining "old" equipment still on the market should be long gone by 2012.

As for Lo band, its well documented that the support is now extremely rare for any equipment in public safety usage, and only ONE state still has not made the move to abandon it. California. In business use Lo band seems to still have support. Call it an educated hypothesis, but when 2020 rolls around, the only VHF Lo Band usage will be in business.
 
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