Ok some one linked me to a site basically stating the the frequency band plan is getting used up. Now I did a basic search and found out the the VHF lo Band has plenty of room now, An The VHF band is starting to clear up, So why is the FCC stating the frequencies are being used up???
You've asked the $64,000 question.
Easy ones first - Low band IS clear in most places. Go back 25 years and that was NOT the case. This is what happened:
- Equipment manufacturers significantly cut back low band product lines
- There is large scale microprocessor noise from all sorts of consumer and industrial devices and computers
- Broadband over Power Lines (BPL) remains somewhat of a threat, although it's been largely supplanted by better ideas
- "Skip" continues to be problematic during upswings in sunspot activity
- Portable radios are very, very inefficient on low band because of helical antennas, inadequate groundplane, and detuning from construction materials
The biggest problem is the first one. Around 1992, Motorola discontinued Micor low band base stations and a while later, they discontinued the Syntor X-9000. Some of the Radius products remained and shops that had to support low band customers found themselves selling Radius mobiles, tone remote panels, power supplies, and outboard amplifiers in order to make base stations. Some of the after-market amplifier manufacturers would not make amplifiers below 35 MHz, negating an entire subband. I was not in a GE shop, but they (and Ericsson and M/A-Com) followed a similar trajectory. As of last year, Daniels was the only "real" base station manufacturer and many users were buying Kenwoods and Motorola CDMs. Kenwood seems to have cut back on their low band product line as some state patrols have been moving away from low band to go toward higher frequency systems.
Noise is also a major issue. That said, being a ham and really liking 6 meters, I think low band has a lot of life to it. But DX is bad for public safety. They need very reliable coverage in town, not coming in from 900 miles away.
VHF channels were 15 kHz apart. At some point, the FCC allowed "Limitation 27" frequencies to be shoehorned in between existing systems on 7.5 kHz channel centers. Now, EVERYONE has to narrowband. But this really did not help because in the places where people needed the spectrum the most, there was already someone on or adjacent to the frequency. A narrowband FM signal is 11.25 kHz wide and the channels can only hold 7.5 kHz before there is overlap. So, the adjacent channel cannot be used close-in to someone who is already there. Rechannelizing things to 6.25 kHz increments would have been much, much better, but then EVERYBODY would have had to change, and the FCC likes paths of least resistance (except for 800 MHz rebanding... not there...). While the pieces would have been up in the air, they could have had standardized splits so the channels could be orderly instead of haphazard. And, all of the high power systems could be "right-sized" so that jurisdictions would have great VHF coverage inside and maybe 3 miles around them, but not half way across the state. There could have been very effective VHF reuse. (I'm dreaming, can't you tell?)
What you don't see in a tabular readout are signal contours. If you take all of those stations, factor it terrain, then create service and interference contours, you will see that that potentially usable frequency is actually used 35 miles away and has to still be protected or interference would occur. Or, there may be a statewide user with a critical mission.
Signal strength is not affected by narrowbanding. A 100 Watt base is still a 100 Watt base transmitting at whatever ERP. INTELLIGIBILIITY is affected by narrowbanding. Digital has helped the recovery somewhat, but then digital coexisting with legacy analog users created an entirely new subset of problems.
The FCC usually doesn't say anything about things being used up. They are given a finite block of resources and usually tell the user community to cooperate to work out how the resources are best divvied up. When the FCC must make a decision solely on its own privilege, no one is usually happy. So, the stakeholders usually do come to some form of consensus. Narrowbanding was a joint initiative of many stakeholders.
We will begin to see some new technologies come out very soon. Some of these are kind of exciting, but in the same token, they may mean that scanning changes significantly. Hang on, because the need for revenue-bearing spectrum will drive a number of things in the coming years.