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Topic: Mobile news broadcasts (Read 458 times) previous topic - next topic

Oracle

I hope this isn't too far off topic, but I was wondering if someone could take a few minutes to help me understand something.

There's mobile news vans around the city that have tall extending antenna towers to transmit their feeds back to the station.  I'm in Toronto where the receiving antenna is the CN Tower, so usually there's a little dish pointed right at the tower.   My question is in areas where there's lots of tall buildings so there's no line of site and areas where RF reception is horrible, what does the van broadcast to.

I was with someone who tried to tell me they bounce the signal from building to building until it gets to the CN Tower, but that sounds like bull to me.  The only other things I could think of though are bouncing off a satellite or the ionosphere, neither of which sound much better.

Thank you if anyone knows the answer.

Oracle

Thanks for your reply.  So if they're 5-10 miles from the CN Tower but surrounded by tall towers in every direction so there is no line of sight, they will use a shorter range wireless transmitter?  Would it be omnidirectional then?  If the area is surrounded by things like streetcar power lines (with nice big sparks), glass, steel, and concrete towers and other sources of interference, can they still get a high quality signal over that distance with a short range transmitter?

Since you mention Helical antennas, I think they also have that.  It looks like the same sort of telescoping tower with a spiral up the outside of the central pillar.

retrolefty

#2
Aug 10, 2011, 04:31 am Last Edit: Aug 10, 2011, 04:33 am by retrolefty Reason: 1
Quote
I was with someone who tried to tell me they bounce the signal from building to building until it gets to the CN Tower, but that sounds like bull to me.


Not BS, microwaves can indeed be reflected off say a building or a mountain ridge or other large surface and get a signal of sufficient strength when there is not a clear line of site route avalible. In fact some fixed commercial microwave links utilize large passive billboard size structures mounted on high hill tops to allow linkage where line of site is not possible.

I have no doubt that the operators of those mobile TV remote vans have learned many tricks to establish a link when out in the boonies where clear paths are not possible.

http://en.wikipedia.org/wiki/Non-line-of-sight_propagation

http://en.wikipedia.org/wiki/Passive_repeater

Lefty

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