and for maybe a year or two, it became a kind of underground music video channel U68.

SuperTV
 

Growing up we had Super TV :


Super TV expanded into the Baltimore area in July 1982 on channel 54 WNUV. Unlike other pay TV channels, Super TV only broadcast from 7:00 pm to 1:00 am Monday-Friday and 3:00 pm to 1:00 am weekends throughout its entire run and never went 24-hour.
Subscribers received a 12 inch by 12 inch brown decoder box and a dedicated UHF antenna which was installed on the roof or on a balcony and aimed at the station's transmitter. When attached to a television, the box would filter in the Super TV movie channel. In the evening, subscribers could view a host of movies that were scheduled to play at that time.

That womeco thing originaly you could listen to the movie but the image was scrambled , i remember we had the guy come out to install but due to where we were it couldn't be done because the strong channel had too many ghosts and the other channel too weak.
there was another that in the 80's abc in ny ws testing at like 3am , it was a weird negative distorted image and the sound was jumbled , almost sounded like a skipping cd or something , this seemed to never get off the ground.

mike

That was probably Tele-First (maybe spelled Tele1st). It existed in Chicago for a short time as well. The idea was to record the scrambled movies on your VCR and watch them (with the descrambler box) at any time you wanted to. Sony made the boxes; I saw one on Ebay a number of years ago. It did not last long.

Philadelphia had this on WGBS 57 in the mid 80s. The supplied antenna was a 24" boom/single-channel yagi OK for the metro area but not out the 50 miles via wooded hills. Super TV expanded local coverage by also using WTVE-51, an independent channel started in Reading 1980, allowing that little antenna to work locally.

IIRC, there was a 15 khz sinewave added to the video, synchronized to invert the sync pulse as Mr Squirrel says.
Also thanks for the missing piece of this puzzle by pointing out this early application of MTS, jogging my memory.
In order to de-scramble, you had to "extract" this pulse from the sound subcarrier, invert it and add it back to the video.
The decoder box looked very homebrew IIRC

In Omaha NE, before cable came to this city, there was a line of sight (probably microwave band) link from a tall building near downtown, (the masonic manor), to a special antenna that was mounted on the subscribers roof or building that allowed viewers to watch a few premium channels using a set top box. I forget what the company was called. I remember repairing a few TV sets of customers that had subscribed to it, and I was amazed that they could actually watch R rated movies right on their TV. Of course it disappeared when cable came in.

I saw similar antennas around Cleveland in the early 90s

Ah yes, sinewave scrambling. You filtered out the 15.734 kHz sinewave from the video itself, inverted it, and combined it with the original video to get a watchable picture. The sound was on a 15 kHz subcarrier on the audio channel, but I don't think you needed that subcarrier for the video (well, you did not with OnTV descramblers, anyway, if I remember right). An LM565 chip and a few other components demodulated the sound for you.

Those services were called MDS (multipoint distribution system) or MMDS (multichannel multipoint...) if I remember right. There were still several of these active in the San Francisco Bay Area in the 1990s (not movie channels but universities with programming, and a local channel called BayTV), but I have not tried to reinstall an antenna and try to see what is still up there in years. They are/were in the 2.1-2.5 GHz range, as you said.

I was going to mention-Ontv was a single channel broadcaster in chicago that came on at 7:00 pm and showed movies and sometimes a special event.A dedicated single frequency uhf antenna was installed and pointed at the broadcaster which fed a set-top descrambler box.The channel would make its transition from normal to scrambled programming every evening.People couldn't believe that they could get r-rated movies on a television set!I don't know if they ever made any money,because the signal was easily hacked and a lot of people could get the service for free.