limitation of T.V transmission

I was watching the tour de france the last week ,in which i encountered
an interesting point. In a tunnel near paris the transmission of the tv
signaL was stoped from the biker.but just, the transmission was at the
start of the tunnel and at the end of the tunnel. there was no coverage
inside the tunnel.
as the transmission was only a line of sight transmission
(through the satelite). hence it could not be transmitted.how can this
limitation be solved .should we use a infrared signal for the
transmission of the video signal inside the tunnel.
if any of you had more information on this topic please do
respond.
Reply to
raghav
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For a relatively high bandwidth mobile transmission such as a TV signal, your options are point-to-point microwave or satellite (roughly the same bandwidth 2-14 Ghz).
20 or 30 years ago, a similar problem of bringing radio signals inside large tunnels was solved by using lossy coaxial cables supplied by Andrew Corporation (in the Chicago area, I believe). This might work for you.
You could also digitize the video stream and feed it to a high bandwidth cellular network, if that were available.
Beachcomber
Reply to
Beachcomber
one way would be to remove the obstruction :)
should we use a infrared signal for the
it is my feeling (but not certain knowledge) that the helmet cam is not a direct feed to a satellite but rather a UHF link to a ground receiver (sometimes a blimp is used in motor racing at least) more often its a mobile repeater in a live truck. the truck is parked ant its antenna is then locked on to a satellite or more often a line of site link to fixed facillities.
coverage could be maintained by placing a receiver / repeater system inside the tunnel IF it was deamed worth the expence.
live coverage of races be they foot, bike, auto are a considerable undertaking and there comes a point when the accountants and management cry "enough already" do the best you can with this budget.
Reply to
TimPerry
The TV Industry also uses handheld antennas for receivers in the microwave band. A human operator manually points the receiver antenna in the direction of the video transmitter source (racing car, helicopter, parade float, etc.) A bit low tech, but it does the job.
Beachcomber
Reply to
Beachcomber
thank you, for your useful advice.now,we are starting a project about it.if you get more information do mail it .
Reply to
raghav

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