Microwave limits?

[stevezodiac]

I don't know where else to ask this. After seeing one of the local Dallas stations doing snow reports from around Gainesville, I am wondering what the length limit is on microwave transmissions?

 

[newsmark]

Microwave signals can go a long way depending on the terrain. In the flat sections of Kansas, 70 miles isn't unheard of. But the signal has to be line of site. A hill or a building (or the curve of the earth) can wipe out the signal. A chopper can get a signal in from quite a distance, but since the chopper's moving, it's hard to keep a stable signal.

There's another factor to consider, too. Some of the stations have microwave relays that help them get more distance. Channel 11 has a relay in Lewisville. 5 has one in McKinney.

Most of the stations have one on their relay in Cedar Hill, one on the "Big Green Weenie" in downtown Dallas and one somewhere in Fort Worth. (Those three are exactly what we have at CW33.)

I'm not sure where else 4 and 8 have relays, but I suspect they each have one somewhere in Collin County. I think 8 might have one in Denton.

The Gainesville shot could have been a satellite shot.

 

[Mediafrog+]

Microwave signals can go a long way depending on the terrain.

Good tropo conditions can enhance microwave signals, often reaching many hundreds of miles. But the transmit and receive antennas need to be pointing at each other.

since the chopper's moving, it's hard to keep a stable signal.

Actually it's easier to get a signal from a distant chopper as its location relative to the receive site is stable. Helicopter microwave systems use a GPS driven autotracker system that keeps the signal locked in (well, most of the time.) It's the close-in shots that can be a headache because of the rapidly changing relative position.

Signal range depends on the chopper's altitude, but it is possible to do a live shot as much as 150 miles away.

 

[arnoldevns]

An engineer I know at one of the stations told me about a time when they went to Montague County for a live shot with just a microwave truck. They tried to establish a picture around 5am for the morning show, but couldn't get a good signal. As the sun came up and the atmospheric conditions changed, the signal was perfect and they used it for several live shots that morning.