Here is one for the space junkies unanimous meeting

[smartcooky]

Well, the whole thing was broadcast "live and uninterrupted" on the VOA Shortwave Service, so they could have been listening to that.

But that would probably have included the Quindar tones, and we didn't hear them. Also, the relative timings of the Capcom and Apollo astronauts would match the recordings made at Houston and available on the AFJ and ALSJ. They don't.

The Quindar tones were used to mute and unmute the uplink transmitter. Because a long series of analog phone lines connected Houston to the uplink station, background noise on those lines would ordinarily be continuously transmitted to the astronauts. The Quindar tones, generated at Houston, activated and deactivated a muting relay at the uplink transmitter so that any phone line noise would be transmitted only when a Capcom was actually talking.

The Quindar tones were removed at the uplink station with a pair of narrow audio notch filters (note the key and unkey tones have slightly different pitches). So the beeps that made NASA so distinctive were, ironically, not heard by the astronauts.

The fact that we didn't hear the Quindar tones in the Jodrell Bank recordings strongly suggests we were hearing the actual uplink transmission. The short pause between one of McCandless's comments and Apollo's reply pretty much confirms we were hearing the uplink via the moon. It certainly should have worked; the uplink was a very powerful signal, and enough would have reflected off the moon to be audible at such a large dish.

Right. I see what you mean

So you think that;

1. Capcom transmits on the uplink; the signal bounces off the moon and is received by Jodrell bank
2. Apollo replies are received directly from the CSM S-Band transmittier

The alternative is that Jodrell Bank had direct access to the uplink signal after the quindar tones were removed. There was no tracking station in England; the nearest uplink was at the DSN Complex near Madrid in Spain so perhaps they had a link into that.

It should be relatively easy to work out what they were listening to by comparing the timing of the communications. If what they are hearing is the reflected signal, then the Capcom broadcasts in the Jodrell Bank video will be considerably later than they would be if they were listening to the uplink signal from the DSN

1. Listening to the reflected signal would give a short delay between Capcom transmissions and replies from Apollo 11
2. Listening to the DSN uplink would mean a long delay (an extra 4 seconds?) between Capcom and Apollo 11 replies

The only hitch I can see is that (I thought) the uplink and downlink were on different frequencies in the S-Band. Two receivers attached to the same antenna?


ETA: Early in the audio, I have transcribed this

0:18 - CAPCOM "That would depend in your point of view" (0:20)

0:26 - APOLLO "Roger that (0:27)

So that is six seconds between the end of CAPCOM's transmission and the beginning of APOLLO'S reply. This transmission takes place at around 20:29UT on July 19 (according to Bernard Lowell's narration) so if that part of the transmissions could be found in the Apollo records it would be interesting to compare them.
 

[ka9q]

So you think that;

1. Capcom transmits on the uplink; the signal bounces off the moon and is received by Jodrell bank
2. Apollo replies are received directly from the CSM S-Band transmittier

Right, that's what I think they did.

The alternative is that Jodrell Bank had direct access to the uplink signal after the quindar tones were removed. There was no tracking station in England; the nearest uplink was at the DSN Complex near Madrid in Spain so perhaps they had a link into that.

I doubt they had any kind of access to the transmission from the Madrid station except by seeing its reflection from the moon. They're much too far apart for line-of-sight, and besides the Jodrell Bank dish was already pointed at the moon, not Spain.

It should be relatively easy to work out what they were listening to by comparing the timing of the communications. If what they are hearing is the reflected signal, then the Capcom broadcasts in the Jodrell Bank video will be considerably later than they would be if they were listening to the uplink signal from the DSN

That's what I've done, though it's complicated by the relatively short excerpts and (in the AFJ version) the PAO's comments cover up some of the overlapping dialogue. But I heard enough to suggest that Jodrell Bank was listening to the reflected uplink. Apollo responds to a Capcom comment in much less than a lunar round trip time, so we were hearing things essentially as Apollo heard them, not Houston.

(The hoaxers like to pick up on supposed examples of missing time delays, so just wait until they discover these recordings. We should be ready. Of course it probably won't bother them that JB received these signals by pointing its antenna at the moon. They may even argue that NASA faked the downlink by lunar reflection, ignoring the several days during which Apollo was nowhere near the moon in the sky...)

The only hitch I can see is that (I thought) the uplink and downlink were on different frequencies in the S-Band. Two receivers attached to the same antenna?

Right, there'd be no problem at all in doing this since the uplink and downlink are in the same frequency band and the two receivers could easily share a common antenna feed and LNA (low noise amplifier). The uplink and downlink frequencies are in a fixed ratio of 221/240, so if you're receiving Apollo's downlink on 2287.5 MHz then you'd listen for the uplink at 2287.5 * 221/240 = 2106.40625 MHz. That ratio is exact at the spacecraft, but as received at Jodrell Bank there would be a slight offset from this ratio because of the relative motion between the spacecraft and the moon. This could in fact be used for independent tracking, although I doubt they were set up to do this.

[ka9q]

ETA: Early in the audio, I have transcribed this

0:18 - CAPCOM "That would depend in your point of view" (0:20)

0:26 - APOLLO "Roger that (0:27)

So that is six seconds between the end of CAPCOM's transmission and the beginning of APOLLO'S reply. This transmission takes place at around 20:29UT on July 19 (according to Bernard Lowell's narration) so if that part of the transmissions could be found in the Apollo records it would be interesting to compare them.

I already found it; it's at MET 078:57:50 during Apollo 11.

[smartcooky]

(The hoaxers like to pick up on supposed examples of missing time delays, so just wait until they discover these recordings. We should be ready. Of course it probably won't bother them that JB received these signals by pointing its antenna at the moon. They may even argue that NASA faked the downlink by lunar reflection, ignoring the several days during which Apollo was nowhere near the moon in the sky...)

Of course, this would not account for the Doppler shift they detected as the CSM orbited the moon. Simply bouncing signals off the moon would not reproduce this Doppler shift.

Also, the Jodrell Bank instruments were so accurate and sensitive that they were able to detect the Doppler shift when the LM stopped descending and began climbing after Armstrong took manual control upon seeing that the target site was a boulder field.


The other thing that bears mentioning is that Apollo 11 was not being tracked using the well-known main dish at Jodrell Bank (on the right in this photo). This was tracking the Soviet Luna 15 lander mission that was taking place at the same time. Apollo 11 was tracked on the smaller Mark II dish (on the left)

[ka9q]

You could in principle fake the Doppler in the signal you're reflecting off the moon to make it appear that Apollo was orbiting the moon. But you'd only be able to deceive a single ground station at a time, and you'd have to know where it is. Ground stations at other locations would expect to see a different Doppler shift, and they wouldn't.

Different ground stations would also expect to see slightly different AOS (acquisition of signal) and LOS (loss of signal) times as the spacecraft orbits the moon. Really close observation of the carrier during AOS and LOS should show a rapid fluctuation in signal strength from the multipath reflections off the moon as this occurs, and these would also occur at different times at different stations.

And there's a characteristic distortion when radio signals reflect from the rough lunar surface. Anyone analyzing a supposed direct spacecraft downlink that's actually reflected from the surface would see this distortion, which would take the form of random AM (amplitude modulation) and PM (phase modulation) of the carrier. A direct PM carrier should be spectrally very pure, as it was used for precise (mm/sec) Doppler tracking.

[ka9q]

Also, the Jodrell Bank instruments were so accurate and sensitive that they were able to detect the Doppler shift when the LM stopped descending and began climbing after Armstrong took manual control upon seeing that the target site was a boulder field.

This would actually be fairly easy for any station that could receive the signal at all. The carrier took a significant fraction of the total transmitted power, and the PM receiver on the ground had to track its frequency and phase at all times. The accuracy of the measurement would depend on the accuracy of your local frequency reference. Ultra-high accuracy frequency references are admittedly much more common today with GPS-controlled oscillators and inexpensive atomic clocks, but I'd certainly expect a well-equipped radio astronomy site like Jodrell Bank to have an atomic standard even in 1969.

You could also analyze the Doppler very precisely without an ultra-stable local reference by comparing the relative frequency and phase of the LM downlink vs the reflected uplink. Since the downlink is phase-locked to the uplink by the ratio 240/221, any shift in phase would have to be due to relative motion between the spacecraft and the moon. This is essentially how the USB tracking system works at each ground station, except that the uplink would be Doppler shifted by lunar reflection so you'd see the LM's velocity relative to the moon rather than relative to the ground station. This would require specialized equipment that Jodrell Bank may or may not have had.

[Echnaton]

Maybe slightly off-topic, but for the people who like ambient music:
http://somafm.com/missioncontrol/

It is an ambient audio stream mixed with NASA input!

Here is one too.

http://youarelistening.to/nasa