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Old 03-03-2019, 12:47 PM   #31
Notebook
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Bit more from L.

Quote:
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.



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.
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Old 03-08-2019, 11:44 PM   #32
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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
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Old 03-09-2019, 12:07 AM   #33
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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...
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Old 03-09-2019, 01:01 PM   #34
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Hello Niels, as kudddel says above some of those signals look like FSK.

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

Quote:
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.
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Old 03-16-2019, 08:28 PM   #35
apollo16uvc
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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)

Last edited by apollo16uvc; 03-17-2019 at 08:46 AM.
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Old 07-30-2019, 08:23 PM   #36
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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...







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