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Comment by betamaxthetape | Hacker News Reader

A great "tear down" of a really interesting device. I'd be curious how you ended up with this?

I'm sceptical that the satellite is Ariel 1 or Ariel 2 for two reasons: (a) Ariel was the British satellite programme, and I think that General Electric would have based the design on an American satellite. (b) Ariel 2 was build by Westinghouse, a rival to GE. My guess would be that it's a generic design, but I would love to hear an update if you find out for sure.

(I'm interested in the Ariel satellites, particularly Ariel 3, since I've ended up with a few of the original Ariel 3 telemetry tapes from the STADAN tracking stations. Still trying to work out a viable way to read / understand them...)

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The paperweight was loaned to me for analysis.

It's pretty cool that you have Ariel 3 telemetry tapes. I agree that the satellite in the paperweight isn't Ariel, but Ariel was the most similar satellite I could find. I'm hoping someone will find a satellite that is a better match. But it could be some obscure proposed satellite that was never built.

What kind of physical format do those tapes have?

They are half-inch wide 7-track tapes. It's the 7-track bit that makes them difficult to read (I have a half-inch machine but it's 8-track). I think it was NASA and a few other government agencies using this 7-track format (or 1-inch 14-track), rather than the 1/2-inch 8-track / 1-inch 16-track used in audio studios.

The workflow for these tapes is described on the Chilton Computing website [1].

(Note: this is analogue 7-track, not to be confused with the digital 7-track format used by early IBM mainframe machines).

[1] http://www.chilton-computing.org.uk/acl/applications/satelli...

There is a Teac 1/2 " that does 8 tracks, you could probably read them one track at the time by judiciously jiggling the height of the head relative to the base of the player. The heads are narrower than a single track so that should work. The analog format is likely simple FSK or some variation on that theme.

It would take 7 passes to get it off assuming only one of the heads lines up with a track at any given time. Keeping the sync between the tracks will be the hard part. I'm in Europe so that probably rules out collaboration on this but if there is some way to get me a sample of such a tape I'll be more than happy to give it a shot.

edit: this machine: https://soniccircus.com/product/teac-80-8-1-2-8-track-analog...

The machine I have is very similar to that (Tascam 38), although the Teac 80-8 has the advantage of being able to run at the correct speed (7.5ips while the Tascam 38 only runs at 15ips).

From reading the papers published at the time (mid-to-late 60s), it seems the encoding scheme was based off a comb-filter, although I don't honestly understand enough to actually describe how it works.

I've had the tapes for around 5 years now, and managed to do basically nothing. It would be good to finally make some progress! I'll send you an email.

The speed isn't that much of a problem, it can be fixed after the signal on the tape is digitized.

Looking forward to your email, I love these kind of projects.

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