RE: Confusion getting homevison onto TV

["Keith Doxey" <ukha.diyha@xxxxxxx>]

Hi Graham,

you CAN NOT have HomeVision overlayed onto 2 or more different sources.

One option for relaying it round the house is to use an old Analogue
Satellite receiver and connect HV to the VCR scart. The advantage in using
a
Satellite receiver rather than a VCR is that many Satellite receivers have
a
UHF modulator that can cover the whole UHF band (21-69) whereas most VCR's
are 30-39 only.

If your primary requiremt is that every TV should display a pop up message
then there is a compromise. Connect the HV to the main TV using the output
of a SCART thereby feeding HV with the output of the main TV's tuner.
Distribute the output of Homevision as composite video and feed it into a
SCART on each TV. Use HV to control pin 8 of the SCART. You can selectivly
"grab" any or all of the TV's. The only failing with this plan is
that TV's
other than the main one may get a different channel whilst the message is
displayed. eg

Normal Viewing			HomeVision Message
Main TV on BBC1			Text overlayed on BBC1
Kitchen TV on ITV			Text overlayed on BBC1

When HV releases control the TV's return to what they were watching. The
only other drawback is if you have another active SCART signal that has
been
overridden because some TV's will revert to that source instead.

One thing I am working on for the KAT5 switcher is the ability to integrate
Homevision for messages in the room where commands are being received. If
you are in the Kitchen and are watching the DVD via KAT5 and sent some
commands to HV then the switcher would select Homevision's input from DVD,
overlay text and temporarily change the source for the kitchen from DVD to
Homevision. It would then revert back to DVD ready for some other room to
use HV. "Broadcast" messages like Caller ID still present the
problems you
describe of not being able to overlay several different sources.

The only way round that is to duplicate the video overlay section of
Homevision x number of times. It would probably be quite easy to drive all
the video circuits with the same text so that every overlay unit did the
same, but if you are goig to that much trouble you want the ability to
display different text in each zone.

There are several video overlay units available. Look at
http://www.decadenet.com/ for the
"BOB-11"

Keith

-----Original Message-----
From: Graham Howe [mailto:graham@xxxxxxx]
Sent: 22 March 2001 17:41
To: UKHA List (E-mail)
Subject: [ukha_d] Confusion getting homevison onto TV


I want to be able to show homevison messages on TVs around the house, with
the messages broadcast over the top of the existing TV program, is this
possible? I can see that it is possible to have a composite video feed
passed into Homevision and then the 'combined image' to be sent back out as
composite video. I can take a composite feed and modulate it so that it
appears on a dedicated channel. I can also use a signal booster/distributor
to pass UHF around the house.

I can see that if I had an aerial feed into a video recorder, took a
composite video feed out of that and into homevision, took a composite
video
feed (with overlay) out of homevision and into an rf modulator, took the rf
output from the modulator and into the booster/distributor I would then
have
'TV overlayed with Homevision' throughout the house, but everyone would be
watching the same channel to see the messages.

Am I missing some simple solution or is it impossible to achieve what I
want
to do.

Just in case this lot doesn't make sense, here is the bottom line:

Can I have homevision messages displayed over the top of terestrial TV
simultaneously on two TVs that are watching different channels?

Regards

Graham





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