Why the push towards higher frequency?

[lenk911]

Bell & Howell handhelds they were also sold under the GE brand

I worked for GE during the transition from BH to their own PC0x/PV0x pagers. What a disaster!. Someone sold some to a weather balloon company. The plan was when the test was done, they would two tone (Tone 99) the pager and it would release the payload. It should have just parachuted to earth. Well, they would false and drop the payload any where OR not respond at all and they would have to chase the balloon across the country or world until the helium leaked out.

The engineering departments final solution was the AH0x. Great pager but too late. Mention GE and pagers and most customers held their noses.

 

[Project25_MASTR]

Frequency availability and urban penetration has been the main push. I don't necessarily agree with some of the posts in the thread though. Specifically coming from the point of view of semi-rural Texas where we are still actively developing and deploying VHF trunking solutions for public safety. I will say, it is a balance though. Channel availability is scarce and the antenna systems can be complex (though they don't generate excess heat as suggested previously compared to 7/800 MHz systems) and we are really beginning to see that urban 7/800 MHz build out for coverage and capacity but utilizing VHF for rural coverage and that realistically is the thought process moving forward if we ever get to that "unified statewide system" it is pretty much guaranteed to be a mixed VHF 7/800 system favoring VHF for rural coverage in counties with populations less than 50,000 people. On average, seeing about 7 times the number of 7/800 MHz sites to make up the same area being currently covered on a single VHF site.

 

[mmckenna]

if we ever get to that "unified statewide system" it is pretty much guaranteed to be a mixed VHF 7/800 system favoring VHF for rural coverage in counties with populations less than 50,000 people. On average, seeing about 7 times the number of 7/800 MHz sites to make up the same area being currently covered on a single VHF site.

Exactly what the California CRIS system is doing. 7/800MHz in the urban/suburban areas, VHF in the rural areas. Should be a good system when it's fully built out.

Big game changer was the availability of multiband radios. Now that all the big manufactures have multiband products, the prices are being driven down.

Multiband radios are -real- interoperability.

 

[freddaniel]

Here is a photo of a Bell & Howell VHF radio with 2-tone decoder. About the size of two cigarette packs end to end.

 

[speedway_navigator]

I worked with a PE who was contracted by Rusk county TX to help with issues on their VHF system. They had the rolling hill terrain that 700/800 does not do well in for the same # of sites VHF handles. We found a bunch of little things that added together became bigger problems.
The sheriff had a 7 site voting system, 3 sites had the VHF omni and UHF link Yagi antennas swapped on the radios.
After the first site I put my VNA to 100-1000 MHz to make those easier to find.

The south part of the county had poor coverage, this photo is the repeater site about 3 miles north of the southern county line, should be obvious why the north had no complaints.

 

[speedway_navigator]

I thought Bell and Howell only did 8mm movie projectors.
I sent Fred's link to a friend in NJ, this was his reply.

I BEGAN my two-way radio servicing when "LINK RADIO COMPANY" was still in
business here in UNION NJ. and the RADIO CLUB OF AMERICA recognized Mr.
Link as the developer of those early 39 mc. mobile FM transmitters.
Link was first to develop the two-unit (RX & TX) VHF FM radios.

Hey Fred - your message posting count is way too low for all your wisdom and expertise. Maybe the forum bosses could start an new one for 'war stories' or 'the good old days' so we don't tie up these posts with topics not directly related.