[HomeBrew] Re: Wireless CATV

[Diane Bruce]

On Tue, Aug 03, 2004 at 02:49:12PM -0400, Steve Uhrig wrote:
> ** Please do NOT cross-post messages in the TO: or CC: field of the e-mail message. **
> 
> On 3 Aug 2004 at 4:00, Jim N2EY, who eschews obfuscation, wrote:
> 
...
> 
> Broadcast video picture is AM. Sound is wide FM on a subcarrier. 

Well, to be pedantic, its vestigal side band VSB. Its still AM though ;-)
 
> If you do an amp, which is not a good idea, you will have a lot of work 
> ahead of you. You'll need a broadband linear amp as you mentioned (sound 
> subcarrier is 4.5 mgacycles up from the video carrier), and the amp will 

Well, he mentioned it works already. I just pointed out that its
not really going to be worth building a separate amp for the FM subcarrier.
I suppose if you were really really bored, you could strip out the FM
at the SAW filter from a junked TV I.F. Then linear translate this. ;-)
Or simply take it to audio baseband and re-modulate a separate FM
transmitter. The TV won't notice, its a common trick in ATV anyway.
You could also take the baseband video sans FM subcarrier
and remodulate an AM transmitter. Unless you are really really bored,
it simply is not worth it.

> To extend the range, improve your antenna, esp on the receive end. Try a 
> simple dipole. 

I agree. If he is not getting into trouble with the FCC i.e. he is
meeting part 15 and he is not annoying the neighbours, a better antenna
is the answer.

> 
> There are cheap Wavecom or equivalent 2.4 gig license-free wireless 
> video/audio boxes which will give 150 feet through inside walls if you 
> play with the antenna positioning and don't need to penetrate any metal. 
> They won't give more range than that unless you improve the receive 
> antenna which is legal.

This would be his better/best bet esp. if he has neighbours. 

The idea of transmitting on channel 3 makes me nervous. If he is on
a farm house or on a very large lot and the signal drops dramatically
outside the house, I suppose its legal (I don't know u.s. regs that well.)
Seeing as he has lready built the thing. But I sure wouldn't do it here.

If I was him, I'd take a small portable receiver outside and *make sure*
he was not going to cause any interference. Getting a visit from
the FCC (or I suppose the CATV people) sure would spoil your day.

> The work in small area coverage wireless video is done with antennas, not 
> with power. See some of the White Papers on my website for details.

Again, agreed.

- Diane Bruce, VA3DB
  AMSAT local coordinator