Apollo Comms Part 15: Combining Voice, Data and Ranging

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00:00 Recap: Apollo's complex modulation stack
02:19 Running the Keysight VSA modulation analysis software
03:42 Phase modulation principle
06:02 Looking at the demodulated Apollo subcarriers
07:45 I added a tube to my spectrum analyzer!
08:04 Adding the ranging signal
10:18 Apollo's careful modulation weighting
11:19 Full Apollo uplink demo

[tomohlsson]

Marc and gang, I've read books on the AGC development and design, I've read books on the Unified S-Band system, I have contacts at Motorola and Rockwell that have provided information over the years, but you have clearly demonstrated how it was done, how it was accomplished and how it works. Your visual demonstration just makes it so clear and easy to understand, it's like I literally had an "aha" moment watching this episode. Hats off to you, Ken, Mike, everyone, your skills are just amazing. Thank you for the gift you have provided us all!

[benmodel]

This is why I love test equipment! It's ability to visualize completely abstract concepts and invisible electromagnetic fields. Makes something that's hard to understand visually apparent. Best one yet Marc, keep up the awesome work!

[leelg]

Your channel is the best proof that we actually landed on the moon. The technology developed for the moon missions is almost magical.

[alpcns]

Absolutely stunning stuff. Fantastic equipment. The engineers and scientists that designed all this equipment and built these spacecraft are absolute geniuses. Using slide rulers, pencils and maybe the first primitive computers. And now, 55 years or so later we have imbeciles that believe it never happened.

Bravo Marc, you are doing spectacular work. I loved the vacuum "tube" as well!

[MarcelHuguenin]

I find this such a fascinating series. Having lived through that era and watched the huge leap for Mankind at age 12 it is so very interesting to learn how the communication actually took place. Thank you so much for sharing and teaching us in such an elegant way using the actual equipment.

[RemcoStoutjesdijk]

"This was done with some good looking HP equipment from the 60s... and some modern keysight ones as well".
Marc, you have a particular modulation there but the message was received clearly :)

[kingofcotham]

I am from the UK what you are doing in this project is so so so historically and amazingly important! I really think that this should get federal support in your country for generations to come!

[tbp-channel]

Chapeau that you all are looking through it after so much research.. and also for giving a stage to the retired engineers of this stuff.. I am enjoying all of your steps in the videos, thanks so much. Nice USB-Tube.. :)

[michaelhaardt]

That was the best explanation of amplitude vs. phase modulation I ever saw. This whole series is actually educational besides highly entertaining.

[danielepatane]

Thanks for adding the visual information on how the system works! It is still fairly complicated today with all the modern equipment we have now I would not imagine how complicated it was back then to visualize and demodulate carriers and subcarriers....very instructive!

[vincei]

Best channel for tech nerds on YouTube.

[davidverbeek]

Completely unrelated to this video, but ever since I started watching your channel I am constantly seeing vintage HP test equipment in movies and TV shows. I am currently watching an episode of stargate SG1 and they are incorrectly using a beautiful hp 8903a audio analyzer as a radio transmitter of all things

[chromosundrift]

Always fascinating Marc, I'm no specialist in these subjects so the recaps and elevator sections are incredibly helpful to my understanding.

[jeremiefaucher-goulet]

From last episode, it was really interesting to see the kind of commands they could send. Now it would be interesting to see how telemetry was encoded on the return link

[gnudarve]

This is some of the best content I've ever seen on YouTube. You and your team have taken a very complex and exotic technology and made it so easy to understand and appreciate, what a gift to the world of engineering and electronics! Thank you so very much.

[donmoore]

Once again you have knocked the cover off the ball. Excellent presentation!

[KeritechElectronics]

Did I ever mention that your projects are mad, bad and totally rad? No? Then your projects are mad, bad and totally rad. I love them so much!
Envious of your lab and test equipment, and even more envious of your skill and knowledge.

Vacuum tube USB key? Hmm, gotta make one with EAA91 :)
BTW seeing a mains frequency meter too. Cool.

[tfhmobil]

Very inspiring and almost a deja vu.

I have some early background on modulation of teleprinters on to carrier frequency equipment, transmitting both data and voice.
This looks very similar, although a different frequency band.
Later I did some DIY stuff, on PET hardware, making modems on telephone lines, and later again, I managed to do a solution on NMT cellular on xx86 hardware.
But after, it was cheaper just to buy and take advantage of more common hardware and protocols.

The fundamentals of all this, must have been developed no later than the 1940ties 1950ties, but still going strong :-)

[jackrubin]

Thanks - your explanations have me believing I can almost understand this stuff!

[danielatbasementtech]

Simply fascinating ! ... thanks for exactly the right level of detail to reactivate my EE neurons.