[LINK] US switch to dig TV - potential for Internet?

[Adam Todd]

At 10:43 AM 26/05/2007, rchirgwin at ozemail.com.au wrote:
>Geez, Stil, get with the program. The whole purpose of all bandwidth 
>is to allow "content producers" to stuff things down the pipe at 
>"content consumers". All else is anarchy. What fool considers 
>democratic use of spectrum when it can be sold to pigopolists for 
>buckets of cash?

Which are acquired from Bank Loans from banks who charge interest on 
the buckets of cash to fill more buckets of cash so that the money 
can be given to someone else for some other over priced, really free 
natural resource, in order to charge more interest and fill more buckets.

>Well, I agree with you, actually. Shoving things down in one 
>direction is not communication, because there's only one party.

Yeah, you mean like 1MB/128K DLS connections?  What's the point!

>Most TV spectrum is useless for the mooted applications, but 
>technology doesn't ever seem to get much traction once visionaries 
>get their hands on the theories of social science.

Well wireless networking seems to be a great option for all this 
awesome and free bandwidth.  Up the power output of base units to say 
1 W and allow anyone to have the ability to connect via hubs and away you go!

Why can't the spectrum be free for everyone?

>Let's imagine, say, a symmetrical channel using a vacated ABC 
>channel at 70 MHz, and let's ignore any question of bandwidth. From 
>transmitter to receiver, those kinds of signals are not particularly 
>directional; so unless you want to encrypt the channel, everybody in 
>range can see what you download. In the upstream channel, the same 
>problem occurs.

70 MHz is a tad low :)  Go up a bit :)  There is plenty of bandwidth 
available and lets face it 70 Mhz to 500 Mhz has a far better TX 
range than 2.4 Gigs!

>(For those who don't believe me, before you dismiss what I'm saying, 
>do some reading. Find out how big an antenna you need to get 
>reasonably directional behaviour from a 4-metre wavelength. You will 
>need a damn big Pringle's can...).

Which is why ideally you want to start around 150 Mhz and go 
upwards.  But the  bandwidth was allocated and hence not easily 
available for spread spectrum applications.  Now it's freeing up, I 
say make it available for spread spec!

>At best, most vacated TV channels will be good for some kind of 
>broadcast - a digital broadcast perhaps, or a data broadcast maybe, 
>but a broadcast nonetheless.

Everyone can have their own TV station :)  Actually, digital 
transmissions on those frequencies would amount to 16-48 channels in 
a bandwidth.  Not bad really.


>Now. I haven't actually done much background reading on the 
>relationship between channel width and data rates, so this is a 
>"thought experiment". Please correct me, anyone with better clue.
>
>If 10 Mbps symmetrical needs 20 MHz channels (ie, one bit per 
>hertz), then *one* customer connection on a 70MHz carrier signal 
>needs a channel from 60 MHz to 80 MHz; and per 100 MHz you have five 
>channels. Even with oversubscription you get, say, 50 customers per 100 MHz.

Not necessarily so.  You are relating transmission bandwidth to bit 
width.  I don't see 200 wires coming into my home!

What you could do is have a bit stream on say 70 Mhz, within a 10Khz 
channel. You can pulse your bit streams nicely in that 
space.  Multiplex and use spread spectrum concepts and you have 
masses of bandwidth available.

>Even if there were 500 customers per 100 MHz of spectrum, I doubt 
>that the economics would work that well...

Ultimately it's more to do with noise and accuracy of the data being 
received, than how many you can fit in a range of spectrum.

The lower the frequency, the more noise, the wider your data channel 
has to be, the longer the range.

The higher the frequency, the less noise, the wider your data channel 
can be, the shorter the range.