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We operate news helicopters at TV stations around the US and they all use a similar system. Basically the right channel of audio is typically the microphone fr
by graupel 13y ago
We operate news helicopters at TV stations around the US and they all use a similar system.
Basically the right channel of audio is typically the microphone from the pilot or reporter and the left channel is the audio feed transmitting what is basically modem data back with the GPS coordinates of the helicopter and some other data.
This data is used at the antenna site to track the helicopter and point the antenna in the correct direction to keep a line-of-site since the transmission system from the helicopter to the receiver is line of site (microwave) based.
It's really cool to sit and watch the receive antenna track and move responding to the movements of the helicopter miles and miles away.
The antenna is on the belly of the chopper here - http://www.imt-broadcast.com/super-pod?cat=Products http://www.imt-broadcast.com/super-pod?cat=Products
The receiver is generally centrally located on a tower - http://www.imt-broadcast.com/silhouette?cat=Products http://www.imt-broadcast.com/silhouette?cat=Products - it's a parabolic dish inside a radome like this.
- toomuchtodo 13y agoHow do you ensure that the receiver on the tower always has LOS to the mobile unit? I can't imagine its on a track to have full 360 degrees of motion around the tower.
- graupel 13y agoSay you have the receiver on the top of a downtown building or a tower and you are transmitting from 1500', there's not too much that can get in the LOS. Receive systems can either be a single antenna, a series of antennas, or (like in the link above) a dish inside a radome - the dish generally can rotate the full 360 since the cable slips through the middle.
- unwind 13y agoI'm not a native speaker, but still have a pet peeve for that one. It's "line-of-sight" (http://en.wikipedia.org/wiki/Line-of-sight http://en.wikipedia.org/wiki/Line-of-sight). Light travels in a straight line over (human-scale) long distances, so you need a straight line free from obstruction to see between two points. I'm sure you know this and just made a typo, of course. Thanks for the additional information about this interesting solution.
- graupel 13y agoYup, just a typo!