800 mgHz HATRED

[902]

Red* are Primary Control Channels, Blue* are alternate control channels ... Jerry

Wyoming has an average population density of 5.14 people per square mile. It is the exception, not the rule.

There are others. Read Larry Sheridan's NPSTC presentation which describes some of the systems in existence.
http://www.npstc.org/meetings/Sheri...tion Jan 2005.pdf#search="VHF Trunked system"
Larry doesn't mention Wisconsin, which could not deploy its system in 90.20 frequencies, so it found a way to build out a system with NTIA frequency resources adjacent to the 2 meter band.

The problem is that in most other places with higher population densities, VHF is not usable in that manner given present circumstances.

 

[N_Jay]

800 MHz 35 Years ago?

Jerry

Sorry, about 32 years.

The allocation was about '74, and the first trunking systems were commercial in '78.
I don't know when the first conventional equipment started being sold.

 

[N_Jay]

I really have to disagree with that. UHF & VHF are far better for trunking. Why do you think the government uses UHF? MANY agencies are finally realizing this.

Jerry

What band is best depends on lots of factors. Trunking requires clean repeater pairs and that is very hard in Part 90 VHF.

The Fed UHF trunking is in UHF because the Feds got those allocations long before trunking even existed. Not because they were better for trunking.:roll:

 

[N_Jay]

Red* are Primary Control Channels, Blue* are alternate control channels

Site Description Freqs
. . . . .
Just a sample of the NEW Wyoming Wyolink VHF trunked system.

Jerry

Why don't you talk to the person in charge of the system and ask how easy it is to get frequencies that work.

 

[SLWilson]

Not Really....

I think it has something to due with urban environments (ie. buildings). Higher freqs like 400 and 800 have better potential to work inside buildings. At least that's what I've heard.

I don't think UHF and even LESS on 800Mhz has ANY ability to penetrate buildings....Communications on those freqs SUCK....Our S.O. has UHF and VHF. When they get out of their cars at the local hospitel and go inside, the UHF is useless. THe VHF will penetrate farther into the building than the UHF (It goes about 30 feet)....Now we have a FD that is still on low-band. They can go all over the hospital and talk!!!! Too bad that everyone else in our county gave up their low-band!!!! Steve

 

[N_Jay]

I don't think UHF and even LESS on 800Mhz has ANY ability to penetrate buildings....Communications on those freqs SUCK....Our S.O. has UHF and VHF. When they get out of their cars at the local hospitel and go inside, the UHF is useless. THe VHF will penetrate farther into the building than the UHF (It goes about 30 feet)....Now we have a FD that is still on low-band. They can go all over the hospital and talk!!!! Too bad that everyone else in our county gave up their low-band!!!! Steve

I love these types of stories.:roll:

No reference to where the base/repeater is, how much power is used, if it is simplex or repeated.

In other words meaningless!

 

[Stick0413]

I love these types of stories.:roll:

No reference to where the base/repeater is, how much power is used, if it is simplex or repeated.

In other words meaningless!

Exactly. Its not so much to do with the frequency but more to do with how much power is behind it.

 

[N_Jay]

Exactly. Its not so much to do with the frequency but more to do with how much power is behind it.

It has to do with the band AND the power, and the distance, and the type of equipment used.

 

[N4DES]

***Trunking systems aside***

What is the advantage of having a conventional 800 mghz system?? From my scanning experience, they are weaker signals, harder to pick up, shorter range... and not to mention the interference/rebanding issues...

Is this one of those "hey, it's new so I have to get it" fads, or is there a real substantial reason for using conv 800 mghz systems?

You should be asking what is the advantage of having a non-simulcast single site system vs. a simulcast/voted system. Trunking doesn't extend your range and can exist in a single site system that could present the same "weaker signals, harder to pick up, shorter range" issues that you noted above.

As to interference/re-banding. A conventional system presents no different issues other than there is no place to go unless the re-banded system is put in place and tested before the radios are re-programmed and the units are switched to it.

 

[Stick0413]

Yeah I mean I am not saying that it has nothing to do with the rest of the stuff NJay. But The biggest part of it is power. The higher power the longer range. I am not saying it might not take more wattage to get signals at different mhzs to the same range. Just that the more wattage you use the longer range you are going to have. Distance yeah the signal is naturally going to get weaker the farther you go away. Equipment yeah that can make a difference too. I wasnt saying it was all to do with power but power is probably the biggest part of it (besides distance anyways.)

 

[OpSec]

Wyoming has an average population density of 5.14 people per square mile. It is the exception, not the rule.

There are others. Read Larry Sheridan's NPSTC presentation which describes some of the systems in existence.
http://www.npstc.org/meetings/Sheri...tion Jan 2005.pdf#search="VHF Trunked system"

Larry doesn't mention Wisconsin, which could not deploy its system in 90.20 frequencies, so it found a way to build out a system with NTIA frequency resources adjacent to the 2 meter band.

The problem is that in most other places with higher population densities, VHF is not usable in that manner given present circumstances.

No, we didn't build out the system. The initial "test" sites were installed, using borrowed federal NTIA frequencies and an FCC waiver, and it never got past that. The issue was frequency allocation, since almost all public safety uses VHF in this state...it left the state without the needed channel pairs to build out the trunked system statewide. At this point, I don't believe the system is even being used on a regular basis. The hardware is in place, and it's just sitting there.

It's a shame, since a VHF trunked system would work out great for the state.

 

[OpSec]

Yeah I mean I am not saying that it has nothing to do with the rest of the stuff NJay. But The biggest part of it is power. The higher power the longer range. I am not saying it might not take more wattage to get signals at different mhzs to the same range. Just that the more wattage you use the longer range you are going to have. Distance yeah the signal is naturally going to get weaker the farther you go away. Equipment yeah that can make a difference too. I wasnt saying it was all to do with power but power is probably the biggest part of it (besides distance anyways.)

No, that's not how it works. You can't just throw more power out and expect your range to increase. A power increase helps with RF saturation of a given area, which allows for better building penetration etc...but it doesn't make the signal go further.

 

[Stick0413]

Ok... I am just learning more and more about this. My question with that is that a radio station that is around here reaches well into NC (listened to it while i was going down there) and a radio station that was about 1mhz down would not even come close (lost it way before i got into NC.) I looked up the power of the signals and the one that reached NC was almost double the power. The towers for each of these stations are within 5 miles of each other. So wouldn't that tell you that the extra power got more distance on the signal. Everything else with them is extremely close to the same (tower location; tower height; right at the same frequency)

 

[N_Jay]

Ok... I am just learning more and more about this. My question with that is that a radio station that is around here reaches well into NC (listened to it while i was going down there) and a radio station that was about 1mhz down would not even come close (lost it way before i got into NC.) I looked up the power of the signals and the one that reached NC was almost double the power. The towers for each of these stations are within 5 miles of each other. So wouldn't that tell you that the extra power got more distance on the signal. Everything else with them is extremely close to the same (tower location; tower height; right at the same frequency)

I few facts.

FCC Licenses to NOT tell you the accurate ERP or antenna height of the system.
The power at a distance has more to do with the type of antenna and the height of the tower then the station power output.

1 MHz is irrelevant in propagation loss.

Sites 5 miles apart could have very different HAAT and path profile between them and you.

 

[N_Jay]

No, that's not how it works. You can't just throw more power out and expect your range to increase. A power increase helps with RF saturation of a given area, which allows for better building penetration etc...but it doesn't make the signal go further.

The best thing for saturation and penetration is proximity, Power is a poor substitute, but is sometimes your only option.

 

[N_Jay]

Yeah I mean I am not saying that it has nothing to do with the rest of the stuff NJay. But The biggest part of it is power. The higher power the longer range. I am not saying it might not take more wattage to get signals at different mhzs to the same range. Just that the more wattage you use the longer range you are going to have. Distance yeah the signal is naturally going to get weaker the farther you go away. Equipment yeah that can make a difference too. I wasnt saying it was all to do with power but power is probably the biggest part of it (besides distance anyways.)

Power out is way down the list.

Proximity is first, (+/-20 to 50 dB, or more)

Equipment (Site and field antenna) is next. (+/- 5 to 25 dB)

Tower Height (+/- 6 to 18 dB aprox.)

Power output (+/- 3 to 6 dB)

 

[Stick0413]

Thanks for the lesson.. lol.. gotta learn somehow... so more than likely it has to do with the equipment more than anything on the radio stations i am talking about.. power has a little to do with it but probably the one station has better equipment is a big thing too.

 

[N_Jay]

Thanks for the lesson.. lol.. gotta learn somehow... so more than likely it has to do with the equipment more than anything on the radio stations i am talking about.. power has a little to do with it but probably the one station has better equipment is a big thing too.

No necessarily "better" equipment.

It could be designed NOT to get to where you are trying to receive it.

 

[K5MAR]

N_Jay just about made the point I was going to make - directionality. Just as broadcast stations have patterns in their coverage area (for instance, a null in one direction to protect another licensee on the same frequency), so do Public Safety users. Say for instance the PD tower is on the north side of the city, the antenna might be designed to radiate more towards the south and less towards the north. If you happen to live north of the area, you might be SOL, even though the same distance to the south the listener has full quieting.

There are a LOT of variables in designing a radio system. That's why the pros get such big bucks to engineer a good system for the user.

Mark S.

 

[N_Jay]

. . . . . .That's why the pros get such big bucks to engineer a good system for the user. . . .. ..

(The bucks are not that big) :wink: