Digitized NASA data tapes

[apollo16uvc]

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Fixed, link now points to an imgur archive with photos.

---------- Post added at 11:59 AM ---------- Previous post was at 11:48 AM ----------

I have finally finished v1.0 of the archive for the NASA satellite tapes.

Sat-53123114313-Version1.0 (Object photos, text file.)

Sat-GFORKS-314N003-Version1.0 (Object photos, documentation, Akai RTR sample, visualized tracks)

Sat-GFORKS-314N079-Version1.0 (Object photos, documentation, Akai RTR sample)

Sat-GFORKS-330N100-Version1.0 (Object photos, documentation, Akai RTR sample)

Sat-SNTAGO-120J827-Version1.0 (Object photos, documentation, visualized tracks)

Sat-SNTAGO-314J019-Version1.0 (Object photos, documentation)

Sat-WINKFIELD-330P001-Version1.0 (Object photos)

 

[Notebook]

More from L.

Morning George, cloudy and damp down here.
Interestingly, for me at least, one of those tapes was manufactured by Pyral which was a French company who invented a particular method of applying the magnetic coating to the base material. Zonal Films, where I worked adapted and used it under licence, but that's off topic.
Very early video tape recorders used a mixture of 'direct record' and FM. Both RCA and the BBC produced linear (fixed head) machines running at something over 100 ips. Surprisingly 'direct recording' was used for the video, and FM for the audio, however these linear machines disappeared once Ampex demonstrated their 2" Quadruplex rotating head system. The first production machine was the VR1000, it produced far better pictures than the old linear machines, and overnight became the broadcast industry standard. The first VTR I worked on was a VR1000B made in the late 1950's, it used FM for video, direct record for audio. The next generation of Ampex VTR's was the VR2000 also using the quadruplex system. FM frequencies were from memory 7.16 MHz sync tip, 7.8 MHz black level, and 9.3 MHz for 'peak white', linear tape speed was 15.625 ips. Also a bit off topic.

The Pyral tape shown appears to be a mixture of direct, or saturation record, and FM. Although you can see some of the lower frequency components quite clearly, I'm not sure how well higher frequencies could be resolved. The FM recordings we made on that Honeywell Instrumentation recorder were only for 'in house' quality checking of our manufactured tapes. The FM carriers were fixed, and from memory no separate track was used for the carrier.

I'm not sure how successful recovering the data by the developing method would be, remember that 10.5" spool will contain at least 2,500 feet of tape, and that's a lot of developing. I also think, although cannot say for sure that the FM signal needs to be demodulated before digitizing. Maybe there is a clever piece of software out there to perform this task.
Regards, L

 

[apollo16uvc]

More from L.

Lots of great information, thanks notebook and L.

I think L misunderstood, the developing is not to digitize the contents. But to verify if there is anything on it at all, how strong the tracks are, and what kind of signals we can expect from each track.

Unless we are able to find a 7-track instrumentional recorder, I plan on using a 1/2 inch Otari 5050 8-track studio recorder. So far the speeds I have seen on documentation are selectable on the Otari unit, 7.5 and 15 IPS.

8 =/= 7 tracks of course, so I hope to accomplish this in two ways:

1. Move the 8-treack head to align one of the 8-tracks with one track on the 7-track tape. Repeat process for all 7 tracks until everything has been digitized.

Question: Are this many replays damaging to the tape, is head gap and track height indifferent enough to give adequate signal?

2. Get a 7-track head, from a broken instrumentation recorder, or a 7-track computer tape drive (Big mainframe reels) and make a head carriage assembly so it can be put in place of the 8-track reproduction head. Connect the 7 tracks to the normal playback amplifiers of the Otari, align 7-track head, and digitize all 7-tracks at once.

Questions: Is output from 7-track computer tape drive and instrumentation head close enough to the 8-track audio head so it can be connected to the Otari playback amplifiers without damage?

Is wiring compatible, was it always basically the same?

Where to get 7-track calibration/alignment tape?


If either one of these has been completed, we will be left with 7 WAV or FLAC audio files for each tape, digitized at 24bit/192Khz. These files contain the raw signals received from the playback machine.

I do not think recording an FM signal like this is problematic? it is just a wave form like any other audio signal right?

I do not think 'direct' recordings should be a problem, as no demodulation is required.

With today's computational power it should be possible to then take the FM wav file and demodulate it with a computer program. As long as we can find the modulation settings used.


Sorry for so many questions, and I am thinking far ahead here. This is so exciting.

Baby steps.
Niels

 

[Notebook]

We both misunderstood, thought you were going to build a hand-held bar-code reader style device and run it along your developed tape!

Personally, I think you should try and get a 7-track machine. If you try to modify an 8-track audio head that will be difficult. If it has a tape guide built into the head, you risk damaging the tape edge if you alter its height. If it hasn't you could use car mechanics "feeler-gauges" as shims to place under the head. Depends on the construction of the tape deck. As long as you don't alter the other tape-guides, you won't damage your tapes

For the rest of your questions, I don't know! I will pass them onto L. for comments.

You won't damage your electronics, the play-back pre-amplifiers will just be overdriven and distort if the flux density on the tape is too high.


I'll have a talk with L. about how a conventional tape deck will handle an FM signal. Depends on the carrier frequency and the deviation(how much the carrier signal changes with the modulation) as to wether it will get through the playback electronics.

It still needs to be demodulated after that.


N.

 

[apollo16uvc]

Hmm, good call on the heads, I took a second look at the Otari MX5050 MKIII-8 headstack, and the rec and repro head seem to have skirts around them.

See here: https://reverb.com/item/10099682-ot...-reel-to-reel-tape-heads-headstack-head-block

It looks like the skirts are integrated around the head, so removing them is unlikely to be an option. Will this allow enough movement to align with every track?

I will be contacting some people who worked with IRIG equipment and hopefully know some units that are still around. I am not sure if I want to ship the tapes though.

I still think a good option would be to take a 7-track head from a broken unit and put it in place of the Otari 8-track repro head. Might need to machine a carriage assembly with spring-loaded screws to align it correctly. Doesn't sound too hard, right?

Could even have the carriage 3D printed, if it isnt used as a ground for the head?

I always though heads could be aligned by turning spring-loaded screws. The photos of the Otari heads don't seem to have this. Seems strange for a pro studio recorder not to have this basic feature? How would you calibrate your deck?!

Best regards,
Niels

 

[Notebook]

I really didn't work with multi-track tape machines, so my info is limited.

The spring-loaded screw arrangement was for the azimuth adjustment, making sure the head gap was at right-angle to the tape motion. I don't think any machine I worked on used that. All head and tape-guides on broadcast machines used locking screws after the tape alignment was finished.

Fitting a 7-track head onto your player could work, depends on the construction of course. You may find the head stacks have mu-metal shields around them:

https://en.wikipedia.org/wiki/Mu-metal
They were used to reduce external magnetic fields affecting the record/play head.
As you are playback only you could remeove these if it helps the mechanics.
Be carefull with them, they loose their "magic" if they are dropped or bent.


N.

 

[Notebook]

Didn't see the other images on your #25 above, and from image number 3 you can see the mumetal shields around the erase head on the left, and the record head in the middle.
They aren't tape guides, they are well clear of the tape path.

The playback head is on the right and unshielded.
In this case you can add metal shims underneath the pb head to find one of the tracks.

I'll have a chat with L. regarding the relative distance you would have to move the head.
For info, all tapes have a reference edge where track spacings are measured from, that can be the top or bottom depending on the standard.

EDIT just had more looks at you images, and each of the heads has a threaded part of the head base, above a dark insert in the head block. The dark insert is
also at the front of each head. Suggests this is an azimuth adjustment from below?

N.

 

[apollo16uvc]

Once I get the recorder I will make some test recordings and visualize the tracks so we can determine how many mm we need to move the head. I'll take precise measurements to keep track of the adjustments.

The head without the shield is the erase head, properly don't want to switch those around!!!

See the MX5050 MK III 8 service manual at the bottom of this page:
https://www.analogrules.com/manuals/otari_manuals1.html

It looks like the head connects to a plug via wires, and those wires might be removable? so I may not have do cut anything. If they aren't removable, i'll have to use a soldering iron. Doesn't seem too difficult... (If I do a head transplant)

 

[Notebook]

Must admit the heads from left to right on your images are the erase head then the record head then the playback head on tape transport. That follows from normal tape construction.

If you look at image 1 the two heads to the left are the record/playback heads they both go to the same edge connector. They also have multiple twisted wire connection.
The head on the right has larger conductors and goes to a separate connector. That is the erase head. Note the fewer cables.


The head without the shield is the erase head, properly don't want to switch those around!!!
No its not, the erase head is always at the entry to the tape path.

N.







N.

 

[Notebook]

Hello again Niels.
Ignore much of what I wrote after 19:00 last night, it was a Saturday...

I can't open the rar. files, they need a password. Not important though as your .img in #28 shows a good drawing of the head-block.

I thought the head block was bolted to the chassis, but it has the heads "upside down" and on top of the tape-guides.

Just have to figure out how much you need to move the head to find the track you want, and see what comes out the audio channels.

Just for info, the only machines I saw in studios were Studer and Revox. Usually studio machines have XLR audio connections, others have RCA phono or DIN.
https://en.wikipedia.org/wiki/XLR_connector

N.

 

[Notebook]

Bit more from L.

Just seen your extra comms with Niels
I think between you and Niels, you have got the mechanical problems of the heads understood. A couple of thoughts, as you said after any vertical movement of the heads the azimuth must be checked, otherwise the high frequency components of the signal will be lost. If you are unable to find a 7 track head block the I'm sure an 8 track one would give enough output, once the required height position was achieved.
As to recovering and digitizing the various signals, the direct recordings as you say require no demodulation so should not be a problem. For the FM tracks I was thinking that a simple "pulse counting" demodulator might work. You can search on the web for detailed principles of how it works, but basically the off tape signal is amplified and fed to a 'clipper circuit'. The edges of the resulting square waves are formed into narrow pulses, these are then fed to an 'integrator' circuit which uses the pulses to reconstruct the original analogue signal. Of course some experimentation would be needed to determine the pulse width required, this would depend on the FM carrier frequency, and the modulating deviation of the carrier.
L

Another FM demod circuit is using the CD4046 integrated circuit. Its a Phase Locked Loop chip, and can be used for this.

[ame="https://www.youtube.com/watch?v=Xl-k8unW9sk"]FM demodulation Part-2 - YouTube[/ame]

Interesting video, they have a very nice signal generator, and the ossiciliscope shows what an FM waveform will look like.
From three minutes in you can see how few components are needed for this chip.

However you do it, you are going to need someone with electronics experienece.

N.

 

[apollo16uvc]

Some interesting new finds, did we play telemetry?

Last week I took the time to play some ESA tapes (1/2 inch 7-track) on my Akai X201D (1/4 inch 4-track)

The tapes played:
1.
SAT: ESRO 1A
TAPE ID: 680841-292-230
ESOC/Section TLM: 13496
DATE: 24 JULY 70
2.
SAT: 720,141
TAPE ID: 1135 05 10A
ESOC/Section TLM: 21554
DATE:
3.
SAT: TD-1
TAPE ID: 1117 09 08 B
ESOC/Section TLM: 16837
DATE: "Day 089"
4.
SAT: TD-1A
TAPE ID: 1118 07 09 A
ESOC/Section TLM: 16672
DATE:

To give you an idea of how satellites sounded in the 60's and 70's check out this website with recordings.


I made a video where I play the tapes and show it on an oscilliscope:

Some remarkable details:
ESRO 1A has a lot of activity at the beginning, it looks like a reference signal that is being adjusted. There pitch changes and there are periods of noise. Eventually we receive a stable signal which is certainly more complex than a simple sine wave.

ESRO 1A:
Oscilliscope:

Spectrogram: seems to show a kind of square wave, would this be satellite data?

Signal played at 20% original speed, sounds like morse code.


The space between the signals is similar to track 6 of the ESRO 1A tape:

TD-1
Oscilliscope : The wave of this signal swells up and comes down again.

Spectrogram : And here you can see that too.

TD-1A
Oscilliscope:
This signal has two harmonic waves:

And when we zoom out, it has a kind of block pattern:

But when it is very interesting to delay the signal, it sounds like a morse code again.
Spectrogram:

Signal played at 15% original speed, sounds like morse code again.

A lot of new information that will take some time to process.

It seems to me quite possible that this is the received data. If we find documents from the relevant satellite with information about telemetry, should it be possible to create a program or circuit that processes the signal?
A program could convert it to a spreadsheet. How much volts the battery outputs every second for example.

I do not know anything about it, but the ESA recordings do not seem to be FM-modulated, since such a wave looks very different.
The NASA recordings are usually not, so apparently AM and FM modulation was not common in recordings from this time.
The NASA documentation usually also has "Direct" recordings and not "FM"

I am looking for people who may be able to help with the relevant satellites, and who are more acquainted with this kind of work.

Niels

 

[kuddel]

It sounds a lot like an FSK signal. A Ham Radio operator might be able to "hear" if it might be PACTOR, AMTOR or RTTY or something similar...

 

[Notebook]

Hello Niels, as kudddel says above some of those signals look like FSK.

Some thoughts from L, who was/is? into amateur radio.

Morning George,
Thanks for sending the latest info from Niels.
I would agree with 'kuddel' that those signals appear to be FSK, although since no demodulation is required I would have said it was a variant of that mode i.e. AFSK. This mode was frequently used by news agencies back in the RTTY days, since the 2 audio frequencies could be received on a regular radio without the need of an accurate BFO.
Toodle pip, L.

later:

No problem George.
The difficulty as I see it is that even after recovering the data. I'm not sure how he can interpret what it all means, still I admire his intentions.
As you said he has got some nice test equipment available, I had a 4 channel version of his Tektronix scope for head changes, lovely kit.
Still packing suitcases.
Toodle pip L

For info RTTY is Radio Teletype, and BFO is Beat Frequency Oscillator. Not relevant to your project, plenty info on the web if you are interested.

I agree with L. that you are well capable of getting the signals off-tape and demodulating them if required. As you say, its knowing what the data on the tape was representing.


N.

 

[apollo16uvc]

Gerald from the unmannedspaceflight forum has the following idea:

When coding the upper potential with 1, and the lower potential with 0, with a more or less fixed clock rate, we get pairs 01 or 10, never 00 or 11. So such a pair, or transition, seems to code a bit .
So it should be fairly easy to convert the signal into a bit stream.

Then it only requires us to find the relevant documentation so that we can write a computer program.

WWV Voice found on beginning of NASA tape

On satellite tape 'Sat-SNTAGO-120J827' a voice can be heard briefly at the beginning. The voice probably tells us the recording time. "The time is 11 5 AM" This is WWV time signal that was THE time standard in the US. It was broadcasted around the US.

The satellite is Upsilon 61, the recording date was Sept 7, 1961

I had to play the recordings backwards.
Here the fragment as an MP3 file.

Between the two voice recordings, "1605" is sent in CW (morse code)

 

[apollo16uvc]

Got 5 tapes that contain Ariel 3 telemetry, recorded at Winkfield.

Finally acquired some 7-track IRIG tape recorder heads, from an Ampex FR-600 no less! two 4-track 1/2 inch heads setup for interlaced 7-track. The 7-track IRIG standard allows for a single 7-track head, or two heads for interlaced 7-track.

Unfortunately not much luck with the Otari MX5050 III. Peter tried an other reel that he knows has audio recorded on it, and the Otari's VU meters do move. But there is still no audio coming out...