----- Original Message ----- From: "James R Miller" g3ruh@jrmiller.demon.co.uk To: domenico.i8cvs@tin.it Cc: peter.guelzow@kourou.de Sent: Monday, November 28, 2011 1:57 AM Subject: Re: Fw: [amsat-bb] AMSAT-DL Hears Mars Science Laboratory X-Band Downlink

Dear Domenico,

...

I was really impressed reading your report about receiving the MSL beacon of MSL on the following page:

Thank you!

It is not difficult; we receive lots of the NASA spacecraft all the time. Stereo-A/B every day, and when they have gone LOS, we (I) check Grail-A and Grail-B and also Juno. When Juno was new, the signal was huge, and enabled the beam shape to be determined with greater depth than before.

Grail-A/B have very high performance Ultra Stable Oscillators (USO) and they are free running. A daily check allows us to check independently that our own station oscillators remain in accurately lock.

Reception of MSL required adding its trajectory data to the spacecraft database, and the frequency to the radio control computer. Provided the given frequency is with +/- 40 kHz of the actual frequency, we can lock onto it in 1 sec via an FFT acquisition process. As it happens, the actual frequency was within 8 kHz of the DSN channel centre, so finding it was immediate.

The station computers can be remotely accessed from home to do software maintenance jobs. Hardware requires people to go to the site, of course. Remote software management is probably the most important part of this story.

Article about telescope systems: http://www.amsat.org/amsat/articles/g3ruh/126.html

Article about Stereo A/B reception: http://www.amsat.org/amsat/articles/g3ruh/127.html

Hoping you are in good health. Wish I was in Italy for the winter!

73 de James G3RUH

--

James R Miller      WWW/PGP:     http://www.jrmiller.demon.co.uk/

Cambridge, England Stardate: 2011 Nov 28 [Mon] 0053 utc

HI Peter, DB2OS and James, G3RUH

I was really impressed reading your report about receiving the MSL beacon of MSL on the following page:

http://tinyurl.com/7t5xjwk

Congrats to you Peter and James , I am sure that in the future AMSAT-DL will be able to launch P3-E and P5-A

Thanks also to JoAnne K9JKM for providing us with the above information.

73" de

i8CVS Domenico