NCSHP Low Band

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KD4MEA

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Does anyone have a timeline as to when the NCSHP will be doing away with their low band radios. Everything in my area is just about totally Viper. Occasionally I will hear Motor Carrier guys talking car to car on low band but not often. Some telecommunicators will simulcast on low band at the same time as Viper but fewer and fewer are now. I have a DB201 low band ground plane that is tying up valuable space on the top of my tower. Any information will be appreciated. Rumor has it that the NCSHP acquired the NCWRC highband frequencies and will use highband repeaters as the backup to Viper. Any good info is appreciated. Just planning ahead to rearrange my tower antennas for the appropriate antennas.
Thanks, Morris
 

jthorpe

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I haven't made a transmission on my low band in over a year. I know it's used some but it's slowly going away.
 

yardbird

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I don't think you will see a transition to strictly 800Mhz for the highway patrol anytime in the near future .

It is a major task is obtaining funding to outfit all SHP vehicles and spares with 800Mhz. mobiles.

That doesn't include ALE and other state agencies.

I would hold on to my low band, because it want be going away for a while.

David
 

sloop

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Lewisville, NC
Low band is still very active in the western NC mountains and foothills....too many elevation changes and not enough repeaters.
 

Flyham

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Low band is still very active in the western NC mountains and foothills....too many elevation changes and not enough repeaters.

This just goes to show that regards to the thread title, it all varies with part of the state your located.
I'd expect Mr Thorpe to be able to work better than 99% of his area from a portable radio, same with the area that I reside in. As the build out continues, I'd expect more and more to be able to do the same.

Also just because I know someone's going to say that one will work over the other, remember this, regardless of the band (Lo-High-UHF-800) they all use the same "link" back to the respective comm centers!
 

kd8x

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From here in Cabarrus County I can hear all these low band channels being still used.

42.38
42.5
42.94
42.82
42.58
42.68
42.60
42.62
42.64
42.52
42.66
42.86
 

RohnsRadio

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Duplin County, NC
i have said it before and i will still say it.
the state does not need to give up low band. they should keep it for back up.

like Forest Gump "....that's all i have to say about that."
 

Flyham

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i have said it before and i will still say it.
the state does not need to give up low band. they should keep it for back up.

like Forest Gump "....that's all i have to say about that."

Why keep something that's costly to repair and has next to no manufacturers support?
Oh and let's not forget, SHP links to the low band sites the same they link to the 800mhz trucked sites, via microwave. So it ain't the rf band you go to worry about, it's the link path to the txmt site.
I'd say the better backup solution would be to repurpose the vhf hi-band freqs, set up some repeaters at some select hi elevation/hi coverage sites and give local and state comm centers access from their local comm towers.

My .02 cents and your mileage may vary!
 

televiper75

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Newton announced this morning, effective at 9AM - no more receiving or transmitting on low band for them.
 

yardbird

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As of 9am this date

Per an email from Raleigh

All Troop G low-band communications has been decommissioned.

They will now be utilizing 800 Mhz. Viper for communications.

David
 

KD4UXQ

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NC SHP Low Band

So this has been on my mind for a while. Why do they not consider adding VHF High to the Viper System in the western part of the state? MOTO makes multiband radios that cover 150/700/800 MHz.

Only need to add the transceivers and antennas to the western NC sites.

NC Uses 220+ sites on 800 MHz to cover the entire state. Virginia only needs 61 sites on VHF High to cover the entire state including the mountains.
 

SquareCircle

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So this has been on my mind for a while. Why do they not consider adding VHF High to the Viper System in the western part of the state? MOTO makes multiband radios that cover 150/700/800 MHz.

Only need to add the transceivers and antennas to the western NC sites.

NC Uses 220+ sites on 800 MHz to cover the entire state. Virginia only needs 61 sites on VHF High to cover the entire state including the mountains.

I think that for some places that works and VA is one of them, however some times there are different design criteria for the systems.

I believe the Virginia system was designed for mobile only coverage, as the VSP vehicles have high power mobile radios and 7/800 portable radios with in-vehicle repeaters/DVRS systems. This is quite a bit different than designing a system for example to provide direct portable coverage outside, which needs quite a good deal more sites than mobile-only.

Another thing is that the cost of combining equipment for VHF systems is quite a big higher than that for 700/800 systems typically.

Just a few things to consider!

--SC
 

KD4UXQ

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I think that for some places that works and VA is one of them, however some times there are different design criteria for the systems.

I believe the Virginia system was designed for mobile only coverage, as the VSP vehicles have high power mobile radios and 7/800 portable radios with in-vehicle repeaters/DVRS systems. This is quite a bit different than designing a system for example to provide direct portable coverage outside, which needs quite a good deal more sites than mobile-only.

Another thing is that the cost of combining equipment for VHF systems is quite a big higher than that for 700/800 systems typically.

Just a few things to consider!

--SC


What sort of design criteria did you have in mind? 800mhz and 150 mhz transceivers can operate at the same site. Voice can be enabled by the extended propagation on 150 mhz. Other mobiles or handhelds can still utilize 800 mhz on the same site. Sure it will cost more but if the area cannot be covered adequately with 800 and without Low Band what are the options?


Still amazing VA only has 61 sites vs 220 for NC. Sounds like Motorola saw lots of dollars in NC and no one got a much needed second opinion. Florida really screwed up too. But taxpayers are a bottomless pit to legislatures.
 

KM4WLV

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It was relayed to me recently that pretty much all patrol vehicles now have mobiles for VIPER and the low band mobiles are starting the be phased out, left out of new vehicles, not repaired/removed if they stop working, etc. Here in Rowan County Troop E is still transmitting on both LB and VIPER, and of course I hear them everyday on the Salisbury P25 system on the link radio they have setup for us. I've still my lowband A9 Syntor in my vehicle and scan all the LB channels for Troop E, and I also have the Troop H channel for Mecklenburg in my scan list which I still here up here as well. I have noticed on the LB side in a few spots in Rowan County where the signal seems to be falling off, but I'm not sure if it's on the transmitter side where it's slowly starting to give up and SHP isn't going to repair it, or if it's the sensitivity on my Syntor going bad which wouldn't be hard to believe since the manufacture date for it is 1986 LOL
 

WG3K

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Still amazing VA only has 61 sites vs 220 for NC. Sounds like Motorola saw lots of dollars in NC and no one got a much needed second opinion. Florida really screwed up too. But taxpayers are a bottomless pit to legislatures.

It's all about capacity. The Virginia system doesn't have the same capacity as the VIPER system does. Because VIPER has so many more site that cover a smaller area (footprint), they don't have to share those sites with a larger geographic area. Because Virginia is using VHF, which has a larger footprint (just based on free-space propagation), they would have to significantly increase the number repeaters at each site to even get close to the capacity of VIPER. This is the same reason cellular sites are much lower and closer together in high population areas because of all the users.

Check to see who is on the Virginia system and compare that to who is on the North Carolina system and I think you'll see a difference.
 

CFP387

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...I have noticed on the LB side in a few spots in Rowan County where the signal seems to be falling off, but I'm not sure if it's on the transmitter side where it's slowly starting to give up and SHP isn't going to repair it...

On my base radio, an old TruckTracker III with a 25' outdoor antenna, it seems like the low band side of Salisbury sounds different from day to day. Sometimes the signal appears stronger and sometimes it appears weaker. Is Faith Mountain still the closest TX site to us?
 

KD4UXQ

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It's all about capacity. The Virginia system doesn't have the same capacity as the VIPER system does. Because VIPER has so many more site that cover a smaller area (footprint), they don't have to share those sites with a larger geographic area. Because Virginia is using VHF, which has a larger footprint (just based on free-space propagation), they would have to significantly increase the number repeaters at each site to even get close to the capacity of VIPER. This is the same reason cellular sites are much lower and closer together in high population areas because of all the users.

Check to see who is on the Virginia system and compare that to who is on the North Carolina system and I think you'll see a difference.

I was primarily referring to the geographic coverage in Virginia. Amazing it only requires 61 sites, which is of course due to increased free-space propagation. Number of subscribers was not in my thoughts since I was asking why not 150 MHz in western NC. Virginia maybe could add 800 MHz sites in metropolitan areas if they wanted to add subscribers there and get the increased density.

I certainly understand Cellular Radio and free-space propagation. None of this explains why 150 MHz cannot be used in the mountain counties.

There may be other technical or cost considerations we are not aware of, that surely the Viper Engineers are. Is it just cost? There seems to be an officer safety issue if loss of low band coverage is not addressed.

If NC does not maintain low band, what will be the solution for the mountain coverage?

This is what I was thinking.

I was wondering why 150 MHz could not be a solution since they need to buy more radios, and they could buy multiband to add to the fleet. The major cost would be adding 150 MHz to the existing sites. 800 Mhz and 150 MHz transceivers could be used on the same sites utilizing different trunk channels. If a radio is only 800 Mhz capable it just uses an existing ID for"Trp F Dist 2" and for 150 Mhz a different ID with maybe the name of "Trp F Dist 2V", or whatever. Same traffic on both. The multiband radio could use either and also be compatible in the rest of the state where 800 MHZ is used.

Except for major metropolitan areas, site density is not as much the concern, but site coverage is.

NC requires 220 sites due to free-space propagation and not capacity. Monitoring sites in NC it is obvious they are very under utilized. NC is very rural compared to other states that probably would have to have a high density of sites to provide enough channels using limited range per site. NY and NJ certainly comes to mind.

Wake county is covered by 6 sites and Durham by 4. Not huge numbers where the number of subscribers is so high. Cellular traffic has a much higher utilization of time slot per channel than 2 way traffic on a trunked system, and cellular has much higher subscriber numbers per geographic area. Trunked systems usually would not need as much channel capacity as cellular for the same number of subscribers. In trunked systems, adding channels up to the max is more often the consideration for increased capacity than adding sites as long as the sites can cover the geographic area. Cellular is usually the other way around due to such high subscriber density. Which as you pointed out, is the reason for limited range and high site density. Cellular sites are certainly engineered to cover a footprint. Many are not even omnidirectional, especially in metropolitan areas. Sites in rural areas are at higher points, sites in metro areas not nearly as high.

It would be interesting to see how they address the coverage issue without low band. I would imagine maintaining low band for safety will be far cheaper than anything I suggested using 150MHz on Viper. Why not keep it? There are still plenty of low band radios available new. There was a big drop in supply years ago. Now seems the options are much better. Vertex certainly makes good radios.Vertex Standard | vx-5500 Low band radios need repeaters so they are still making low band transmitters and receivers. https://midlandusa.com/product/71-0100a-analog-transceiver/
 
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Quantar22

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First off I personally like VHF as a suggestion but I think you are missing the point that these systems are designed completely differently... The Stars system was designed for state agencies only and is designed for 100W mobiles.... VIPER was designed for state, federal, local users and was designed for a 3W handheld radio held at chest level with 95% in street coverage. There is a big difference in design parameters.

I am not trying to be insulting to you so please do not take it that way but there are many reasons that 800 was chosen for the state system. Unlike Tennessee who has a VHF/800 system from the design phase NC chose 800. Why they did I do not personally know. I do know this there are many agencies (local, state, federal) who have better coverage on VIPER than they had with their legacy systems. One county in the mountains that I will not mention has better coverage on 800 than they have on their VHF system.. might I add their VHF system shares the same exact tower sites that VIPER has. I know someone will say but VIPER has sites in the adjacent counties that provides coverage into those counties and yes they are correct.... BUT the tests were done using only the same sites in that county on 800..

I would suggest you spend some time reading on Motorola 7.X P25 trunking as well. I am not going to comment any further on this but please do not bash those who made the decisions they did to go with 800 nor infer they were in cahoots with Motorola. The train has left the station and it is too late to do such a big system direction/type change at this point. 800 coverage in WNC is pretty darn good and in many places 800 coverage is better than LB coverage from the troopers I have spoken with.

Do I think VHF merits looking at for some type of coverage absolutely as it is a great interop tool for counties to have. Most counties have some sort of VHF subscribers even if they are on 800 or UHF. This is very handy when interop with federal agencies is desired along with other reasons. I think a VHF system as some sort of conventional backup would be great but VHF trunking is a whole 'nother deal. VHF combiners/multicouplers can take up a huge amount of physical building space even if you can find frequencies that will fit into a combiner/rx multicoupler. Another problem with VHF is the increased coverage versus 800 due to path loss being less. So when you try to keep 800 co channel use to say 75-90 miles between sites you would have to go to 150-200 miles on VHF to ensure a good frequency reuse. When you are bordering with Georgia, Tennessee, South Carolina, Virginia, and Kentucky you have to make sure those VHF frequencies are clear in those states also. It is a mess to say the least...

Another problem is with 800 when a channel is needed to be added one generally looks at 150-250 KHz of spacing between channels to make sure the combiner will tune up... That is generally simple to find with help of frequency coordinators. With VHF/UHF if a frequency is found it could require a complete rework of the combiner/rx mulitcoupler system. Those systems are terribly expensive so a rework to add one channel could be $10-20K. I am sure if Stars was to go for the portable coverage you would see the number of sites at least double if not possibly triple. VHF antennas on radios are not much more efficient than a 50 ohm dummy load with no gain... luckily at 800 you get some gain as well. 800 base antennas have more gain than their VHF counterparts and generally the noise floor at tower sites is lower on 800 than VHF. VHF noise floor at some sites can regularly be in the -105 to -95 dBm level. Most 800 sites are in the -115 to -120 range. That is a big difference also. With the difference in frequency and loss being calculated there is about 16 dB difference between 150 and 800 MHz for path loss for signals transmitted from the same location.
 
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