Input needed: Low band NEW multi-user system
Posted: Thu Jan 25, 2007 8:25 pm
I'm working with a rural county. About 450 square miles, rectangular shaped, county seat in the middle, various cities and towns throughout the county, rolling hilly topography with a few REALLY cavernous hollows and valleys.
Right now, public safety radio is a hodgepodge. The cities all run VHF simplex or repeater stations, a few with horrid input/output issues, and most with no more than 40 watts RF output. The sheriff has a 110 watt VHF repeater with a remote receiver. They dispatch two part-time village police agencies (one car each) and have two or three county cars on the road at any time. No vehicular repeaters anywhere in the county.
Fire: One department uses VHF Low (33 MHz), the "county" fire dispatcher uses a UHF local government repeater with about 70% portable coverage, and one department is on a 50 watt VHF high band repeater.
The county road department uses 37.98 and a 453 MHz highway maintenance repeater. Base to mobile coverage on UHF is about 85-90%, low band is countywide but the channel is shared with a much larger highway department about 30 miles away, so interference routinely kills them. School buses either use CB radios or have a 460 MHz business band repeater system with decent coverage.
No other county or township agency has any radio communication at all.
We'd like to standardize everything as much as possible, for interoperability, homeland security, and just plain old common sense communications. This project is dependant on money, but the county formed a technical advisory board (I am a member) and things are moving ahead slowly.
As you might imagine, the politics of radio system design are quite interesting. Most agencies feel they have a good radio system and want everyone to "standardize" on their band. I am looking at a different direction.
Low band. Specifically, 45-47 MHz.
I've worked this out on paper, and here's what we would probably need:
1 - Sheriff dispatch
2 - City #1 police dispatch
3 - City #2 police dispatch
4 - Police tactical common
5 - Fire dispatch
6 - Fireground
7 - Emergency Medical Service and Rescue
8 - EMA/Disaster
9 - County road department
10 - County government common
11 - City #1 public works
12 - City #2 public works
13 - Township road and maintenance common
14 - School District #1
15 - School District #2
16 - School District #3
From searching the FCC files, there are dozens of frequencies available in the 45-47 MHz band on the old Police, Fire, Local Government and Special Emergency assignments. Most were never used in this area, even back in the day, and all those agencies 50-100 miles away that did use these frequencies have migrated to high band or UHF.
Even with narrowbanding, there are precious few VHF and UHF repeater pairs available. So may of our surrounding counties have scarfed up a dozen or so new channels ... thete just isn't a lot left to pick from.
I have always been a low band fan of sorts, especially for rural, hilly areas. I really like the stand alone design of low band, where mobiles and base stations operate on their own stick and steam, and aren't dependant on a trunking network or a repeater station for wide area coverage. In a disaster situation, you just can't kill 'em.
I'm leaning toward mobile repeaters in law enforcement vehicles, fire trucks, and ambulances, with UHF portables capable of "one hop, two hop" operation where the PAC-RT can be bypassed for on-site communication, but the operator can still monitor the dispatcher and not get "lost".
Has anyone else put together such a proposal? Do you foresee any problems? I am concerned about equipment availability, especially since most manufacturers have essentially given up on 30-50 MHz.
Ideas? Comments? Rotten Tomatoes to throw at me?
Right now, public safety radio is a hodgepodge. The cities all run VHF simplex or repeater stations, a few with horrid input/output issues, and most with no more than 40 watts RF output. The sheriff has a 110 watt VHF repeater with a remote receiver. They dispatch two part-time village police agencies (one car each) and have two or three county cars on the road at any time. No vehicular repeaters anywhere in the county.
Fire: One department uses VHF Low (33 MHz), the "county" fire dispatcher uses a UHF local government repeater with about 70% portable coverage, and one department is on a 50 watt VHF high band repeater.
The county road department uses 37.98 and a 453 MHz highway maintenance repeater. Base to mobile coverage on UHF is about 85-90%, low band is countywide but the channel is shared with a much larger highway department about 30 miles away, so interference routinely kills them. School buses either use CB radios or have a 460 MHz business band repeater system with decent coverage.
No other county or township agency has any radio communication at all.
We'd like to standardize everything as much as possible, for interoperability, homeland security, and just plain old common sense communications. This project is dependant on money, but the county formed a technical advisory board (I am a member) and things are moving ahead slowly.
As you might imagine, the politics of radio system design are quite interesting. Most agencies feel they have a good radio system and want everyone to "standardize" on their band. I am looking at a different direction.
Low band. Specifically, 45-47 MHz.
I've worked this out on paper, and here's what we would probably need:
1 - Sheriff dispatch
2 - City #1 police dispatch
3 - City #2 police dispatch
4 - Police tactical common
5 - Fire dispatch
6 - Fireground
7 - Emergency Medical Service and Rescue
8 - EMA/Disaster
9 - County road department
10 - County government common
11 - City #1 public works
12 - City #2 public works
13 - Township road and maintenance common
14 - School District #1
15 - School District #2
16 - School District #3
From searching the FCC files, there are dozens of frequencies available in the 45-47 MHz band on the old Police, Fire, Local Government and Special Emergency assignments. Most were never used in this area, even back in the day, and all those agencies 50-100 miles away that did use these frequencies have migrated to high band or UHF.
Even with narrowbanding, there are precious few VHF and UHF repeater pairs available. So may of our surrounding counties have scarfed up a dozen or so new channels ... thete just isn't a lot left to pick from.
I have always been a low band fan of sorts, especially for rural, hilly areas. I really like the stand alone design of low band, where mobiles and base stations operate on their own stick and steam, and aren't dependant on a trunking network or a repeater station for wide area coverage. In a disaster situation, you just can't kill 'em.
I'm leaning toward mobile repeaters in law enforcement vehicles, fire trucks, and ambulances, with UHF portables capable of "one hop, two hop" operation where the PAC-RT can be bypassed for on-site communication, but the operator can still monitor the dispatcher and not get "lost".
Has anyone else put together such a proposal? Do you foresee any problems? I am concerned about equipment availability, especially since most manufacturers have essentially given up on 30-50 MHz.
Ideas? Comments? Rotten Tomatoes to throw at me?