Re: [amsat-edu] Link Budget for Cornell University's student built satellite Violet
Hi Danny You did a good job on the link budget. Jan King is the author and he will comment if you send him a copy. Here are my comments.
1. Patch antennas are hard to put on a cubesat because of their size. 2. If you fly dipoles they have very deep lobes of the end of the ends and will cause deep fades when the antenna alimented off the ends. 3. The ground antenna when at 5 degrees elevation look into the warm earth i.e. 290 deg K
For a reality check go copy AO 51. Copy the telemetry beacon. It uses FSK modulation and if you chose GMSK it is several db improvement over FSK. The antenna are turnstile with 2 db gain circular polarized. AO-51 keeps the antennas nadir pointing so there is very little fading due to polarization misalignments and this is a challenge on 10 cm cube.
If you make it to the cube sat conference at San Louis Obispo look me up I am 6 ft tall with red hair and 64 years old.
Good luck nick
-----Original Message----- From: Yoon Ho Lee [mailto:yl482@cornell.edu] Sent: Wednesday, April 15, 2009 9:18 AM To: Nick Subject: Re: [amsat-edu] Link Budget for Cornell University's student built satellite Violet
Hello Nick,
It seems like the listserv denied my attachment. Here are the files. Thank you for your interest and help!
-Danny
Nick wrote:
Hi Danny I will review your link budget but it was not attached to your email.
Please reply directly to this email off list
nick
-----Original Message----- From: amsat-edu-bounces@amsat.org [mailto:amsat-edu-bounces@amsat.org] On Behalf Of Yoon Ho Lee Sent: Tuesday, April 14, 2009 7:12 PM To: amsat-edu@amsat.org Subject: [amsat-edu] Link Budget for Cornell University's student built satellite Violet
Dear whom it may concern,
I'm Danny Lee from Cornell University's student built satellite team Violet, working on Electrical Subsystem, specifically Telemetry and
Control.
For those of you familiar with CUSat, our team is under the same UNP program, on the 6th competition.
I have worked out a preliminary link budget from limited resources and knowledge, and I would greatly appreciate any input from experts out
there.
Please read the note before proceeding to the spreadsheet.
Thank you very much in advance, and I look forward to your input.
Sincerely,
Danny Lee Electrical Subsystem, Team Violet, Cornell University
Our satellite is actually a nanosat, with 50cm by 50cm by 60cm (W x L x H), so we do have enough space to use two patch antennas. Would you like to explain more about the receiver noise temperature ? I'm having a hard time estimating how much effect the noise temperature has on a link. Thank you.
-Danny
Nick wrote:
Hi Danny You did a good job on the link budget. Jan King is the author and he will comment if you send him a copy. Here are my comments.
- Patch antennas are hard to put on a cubesat because of their
size. 2. If you fly dipoles they have very deep lobes of the end of the ends and will cause deep fades when the antenna alimented off the ends. 3. The ground antenna when at 5 degrees elevation look into the warm earth i.e. 290 deg K
For a reality check go copy AO 51. Copy the telemetry beacon. It uses FSK modulation and if you chose GMSK it is several db improvement over FSK. The antenna are turnstile with 2 db gain circular polarized. AO-51 keeps the antennas nadir pointing so there is very little fading due to polarization misalignments and this is a challenge on 10 cm cube.
If you make it to the cube sat conference at San Louis Obispo look me up I am 6 ft tall with red hair and 64 years old.
Good luck nick
-----Original Message----- From: Yoon Ho Lee [mailto:yl482@cornell.edu] Sent: Wednesday, April 15, 2009 9:18 AM To: Nick Subject: Re: [amsat-edu] Link Budget for Cornell University's student built satellite Violet
Hello Nick,
It seems like the listserv denied my attachment. Here are the files. Thank you for your interest and help!
-Danny
Nick wrote:
Hi Danny I will review your link budget but it was not attached to your email.
Please reply directly to this email off list
nick
-----Original Message----- From: amsat-edu-bounces@amsat.org [mailto:amsat-edu-bounces@amsat.org] On Behalf Of Yoon Ho Lee Sent: Tuesday, April 14, 2009 7:12 PM To: amsat-edu@amsat.org Subject: [amsat-edu] Link Budget for Cornell University's student built satellite Violet
Dear whom it may concern,
I'm Danny Lee from Cornell University's student built satellite team Violet, working on Electrical Subsystem, specifically Telemetry and
Control.
For those of you familiar with CUSat, our team is under the same UNP program, on the 6th competition.
I have worked out a preliminary link budget from limited resources and knowledge, and I would greatly appreciate any input from experts out
there.
Please read the note before proceeding to the spreadsheet.
Thank you very much in advance, and I look forward to your input.
Sincerely,
Danny Lee Electrical Subsystem, Team Violet, Cornell University
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Yoon Ho Lee