[NLRS] Important matter for VHFers

[Dr. Gerald N. Johnson]

On 4/22/2011 9:39 PM, Marciniak, Ed wrote:
> Perhaps it would be a better argument that:
>
> The cellular providers should adopt a lower bandwidth codec such as
> AMBE or IMBE that could double the capacity before relentlessly
> seeking more spectrum.
>
The have spent money on what they have, they don't want to change,
though lower bandwidth CODECs would probably make their hardware work
better. In urban areas they are going to tiny cells because a city block
or two can use up more bandwidth than a cell tower can supply all at
once so the cell size is shrinking. I just saw a news headline that AT&T
is offering shoe box sized cell sites for such applications. I haven't
seen explained how the myriad show box sized cell sites communicate with
each other and the central office, but that bandwidth is running into
limits too.

Part of the problem is that we showed the world how handy it was to have
low cost mobile communications, and now the cell phone industry has made
that low cost mobile communications even more mobile and available to
everybody. And the demand for frequencies is much increased.

> That lower frequncies increase the cost of certain components in
> radio hardware, as well as antenna size...and that it is not the best
> place to add a spectral allocation.
>
Especially a limit for cell phones in the hand. Antennas for LF are large.

> Data over 9600 bps, and atv are two modes that can't be served by 2m
> allocations. Sure they could be done on 1.2ghz but we've leaned from
> 800mhz digital radio that certain terrain and foliage conditions can
> cause coverage issues on long hops. To arrive at reasonable capacity
> cellular networks (usually) place towers close enough together that
> that isn't an issue.
>
If we worked at it we could get higher speeds than 9600 in 15 KHz
bandwidth. It would take multiple tones like land line modems that get 
nearly 56 KB in less than 3 KHz bandwidth. It would take serious modem 
modifications to accommodate varying pass bands without having to 
negotiate phase and amplitude equalization for each transmission. 
Probably would have to use complex forward error correction.

>
73, Jerry, K0CQ