[LINK] TV Spectrum for Last Mile

[Adam Todd]

At 10:54 AM 9/06/2007, George Bray wrote:
>>So. Does anyone on Link care enough about the broadband-over-TV-channels
>>idea to explain how it stacks up into a business case that genuinely
>>competes with DSL etc?
>>
>>RC

It doesn't.

>1) The early work on BushLan by ANU said they were achieving
>100-200kbps. Many years ago now.
>
><http://wwwrsphysse.anu.edu.au/bushlan/background.html>
>
>2) When I investigated this issue for the wireless broadband enquiry
>my discussion with management of Broadcast Australia indicated that
>yes, using the VHF band was certainly possible and there existed at
>the time USB modems that worked to 400kbps. That technology might be
>better now too. The upstream link still uses a copper modem line, at
>whatever that will do.

This is great if you are a user who doesn't sent files via email or 
HTML designed email's with lots of graphics and extar's (smirk)

But what if you don't have access to a land line (in the bush).

The system is useless.

It would be better to backchannel on the microwave links that are 
around the country, than to try and install a copper cable to a 
homestead in the middle of nowhere.

>3) We have world's best expertise in RF electronics in the CSIRO, so
>it's plausible that IP over VHF/UHF could be developed further.
>Perhaps specifically to make good use of the national BA network for
>regional users.

And there is Trunk Radio and it's ability to forward packets and switch.

>Using the TV spectrum for a downlink has been diss'd on this list
>before, based on the experiences of people trying to get DVB-T
>television channels. Certainly, it's not ideal reception everywhere.
>But where it does work, it works well. That digital TV channel you're
>getting is up to 10Mbps coming down that antenna.

The power output is too high and again, the issue of privacy of your 
data and everyone else's streamed in a wireless environment that is 
open to interception hundreds of km's away is of course questionable.

>At this point in the debate, however, I'd say that IP over VHF/UHF is

Amateur radio operators had been doing this for years.  Unfortunately 
the law changes in 1997 and 2001 caused the entire 144 Mhz network to 
be shut down because they were technically becoming carriers without licences.

The Government didn't want to hear about it and didn't care.

For some people this was the ONLY way they could access the Internet, 
and now they have no access at all.  Even better, it cost nothing 
:)  (Except a Ham Licence and some kit!)

>I firmly believe that the VHF/UHF network can contribute to more
>diversity in the BB last mile solutions. If the regional copper
>network is not capable of high downstream speeds, why not use existing
>high-bandwidth, wide area RF?

I do agree though :)

But then, my mind set is placed in a world where everyone is honest 
(including ones own parents) and people work together for common 
goals and survival.

Sadly this is not the world we live in.