Wednesday, September 2, 2009

The return of Channel 1

Some people wonder what happened to TV channel 1 here in North America.

Well, TV broadcasting actually began before World War II, but with the outbreak of war, it was suspended. In 1945, when the war was over, the bands for both TV and FM were realigned (much to the detriment of Edwin Armstrong's fledgling FM radio network - all of the FM receivers sold before that time were instantly obsolete). Channel 1 was from 44-50 MHz, and channel's 2 through 6 were as they are now.

That had the rather uncomfortable distinction of sandwiching the amateur 6 meter band right between two TV broadcast channels. Fortunately for us hams, channel 1 was reallocated to land mobile services. Since by that time people had already bought a nontrivial number of TVs, the channel numbers were not changed, and so to this day, channel 2 is the bottom of the TV band at 54-60 MHz.

Spring forward to today. KAXT switched on their ATSC transmitter a few weeks ago, putting out 12 streams of video and 3 of audio on virtual channel 22 (RF channel 42). This collided with KRCB, which was also using virtual channel 22 (via RF channel 23). Back in the days of analog broadcasting, the two used to collide with each other, since they were both on channel 22. The net result was to deny those of us here in the South Bay any chance at all of receiving KRCB, even though with a good enough antenna we had a good shot at it.

Well, the long and short of it is that virtual channel number "collisions" between broadcasters are undesirable. Some receivers get very confused when there are multiple 22-1 streams. Some prefer the most recently tuned one, some allow two to exist... It's very messy.

Well, KAXT has asked the FCC to change their virtual channel number to 1. The FCC more or less said, "well, if that'll fix it, sure." The PSIP TVCT spec does allow for a channel 1. It'll be interesting to see how many tuners balk at it, though.

It'll be interesting to see what KTVJ decides to do. In theory they have three choices of virtual channel - 4, 20 and 36 - all of which are already in use.

My suggestion? They should pick 37. It's one up from 36, which is their current branding identity (which they can't use since it's taken by KICU), and TV channel 37 has traditionally been unallocated because it is actually a radio astronomy quiet channel (there's some interesting physics that manifests itself at or near 49 cm).

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