Whipped Cream Difficulties

The high in Austin today is estimated to be 104. I think it is time to bring out something I’ve been holding in reserve.

“Land of White Alice”. No, this isn’t a Lewis Carroll thing. “White Alice” was a communications system in Alaska that used “tropospheric scattering” for over-the-horizon communications links.

The tropospheric scatter system operated around 900 MHz, and utilized both space diversity and frequency diversity, multiplexing a maximum of 132 simultaneous voice channels. The tropospheric hops used pairs of 60 ft (18 m) or 120 ft (37 m) parabolic, billboard like reflectors pointed at a low angle into the horizon. The radio waves were scattered by the tropopause, returning to Earth beyond the horizon, allowing communication between stations hundreds of miles apart. Having two antennas allowed for space diversity, meaning that if tropospheric conditions degrade on one path the second path might still be clear and communications would not be disrupted. For frequency diversity, each antenna transmitted two separate frequencies. Using both frequency and space diversity was called quad diversity. System power output for most shots was 10 kW and used 60 ft (18 m) antennas. Longer shots used 120 ft (37 m) antennas with 50 kW and shorter shots used 1 kW and 30 ft (9 m), round parabolic dishes.

The video makes it sound like White Alice was a major communications link for civilian traffic, but from what I’ve read elsewhere, it carried mostly military communications at this time (though it was used to coordinate between military and civil air traffic). The system went into place beginning in 1955: by 1970 or thereabouts, the military considered it obsolete, and transferred it to RCA Alascom for civilian use until the late 1970s.

I’m putting this up for two reasons: in addition to my interest in cold war tech, there’s also a lot of great vintage footage of Alaska. There’s even an Alaskan bush pilot, RoadRich.

Bonus: “Seconds For Survival”, from those wonderful folks at the Bell System.

The film tells how the North American Air Defense Command links NORAD, Sage, SAC, the DEW Line (Distant Early Warning), BMEWS, White Alice System, picket ships, Texas Towers blimps and air ships and air patrols into a single giant warning system to protect Americans from Soviet attack.

This entry was posted on Monday, July 13th, 2020 at 2:00 pm and is filed under History, Planes, Radio. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.