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Nick Flowers August 12th, 2008 01:13 AM

TV Transmitter Feeds
 
OK, this is so obsessive that makes train spotting seem mainstream. However, there may be another nerdlet or two out there with which this chimes!

TV transmitters have to get their signal from somewhere, either by landline, or microwave or in the case of relay transmitters simply by picking up off air from somewhere else. I expect now some get the signal from satellite. Some of these routes to remote transmitters can be tortuous in the extreme. The (ex) BBC transmitter at Eitshal in the Outer Hebrides (UK) is the best I know of. From Rosemarkie (Inverness), a main transmitter connected to the main network, there is a chain of passive and active relay stations (unmanned) erected with great difficulty over the Scottish Highlands right across to the Western coast, where the final leg across to the Western Isles is multi-frequency to combat phase cancellation from reflections off the sea. Some of these relays had to utilise ponies to get the equipment on site - no roads.

Other countries are much larger and have more remote areas than the UK and if anyone knows of a more eccentric transmitter feed route, do tell!

Nick F.

Tripp Woelfel August 22nd, 2008 06:27 PM

Ah... the notorious studio-transmitter link.

I worked in radio years ago and all the stations with remote transmitters (most of them) used either phone lines or microwave relays. Given televisions much larger bandwidth requirements, long-haul phone lines would get rather dear.

Before satellites, the three US networks would use microwave repeaters to bring the network signals from either New York or Los Angeles to the local market outlet.

Stringing a bunch of microwave stations together across the US was probably less of a challenge than the low altitude transmission you refer to. Getting programs across the flat American prairie meant building tall towers and finding whatever passes for a hill in those parts. Getting the signal across mountains would probably be simpler since you could likely go farther before the curvature of the earth got in the way.

I have no idea how they got the equipment to peaks in the Rockies or Sierras, but I would suspect that helicopters played a role.

C-band satellite dishes have been hauling in distant signals for cable TV providers for at least two decades so the reliability has been well perfected. I'm not sure if the broadcast networks even use microwave anymore except possibly as a last resort backup, but I've been out of the business for many years.

BTW... up until the acceptance of satellites by the networks as a transmission media, network TV outlets in Alaska and Hawaii had to wait for physical tapes from the network to arrive before they could show the latest evening dramas and sitcoms. Thus those in the two newest states had to wait about a week for their latest sitcoms, dramas and soaps.

Nick Flowers August 23rd, 2008 12:56 AM

Routing the microwave towers
 
Thanks for that, Tripp.

When the microwave network was being rolled out in France all those years ago, they found that they were putting the towers on the same sites as those chosen for the optical telegraph system installed in Napoleonic days. The French optical system was HUGE! it stretched from Paris as far as Italy and even down to what was Yugoslavia. They used tall posts with a horizontal bar on top with things like old style railway signals on each end. We had a similar but less extensive system in England. A time signal from London to Plymouth took less than five minutes to be sent and the acknowledgement to come back - a round trip of over 500 miles.
So line of sight was the common factor with placing the stations of both systems!


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