[amsat-bb] swr explained
Hi all I ran across a Bell Lab video on SWR. He shows a mechanical analog to describe transmission line. I recommend viewing to your students. In a few minutes he describes what it took me months to understand. Nick url http://www.youtube.com/watch?v=DovunOxlY1k ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: e: Satellite technical question
Thanks Domenico for the reply. You are correct the physical temperature and the equivalent noise temperature are not related. Bob wb4apr suggested that a 1/4 wave antenna in LEO has a noise equivalent temperature of ~ 150 k . What is the consensus of the group ? We are trying to do an uplink budget and one of the variables is the system temperature. nick -Original Message- From: i8cvs [mailto:domenico.i8...@tin.it] Sent: Monday, September 10, 2012 4:32 PM To: Nick Pugh; Amsat - BBs Subject: Re: [amsat-bb] Re: e: Satellite technical question Hi Nick , The equivalent noise temperature of an antenna do not depends by it's phisical temperature but only by the noise temperature emitted by the object that the main lobe of the antenna is looking. The equivalent noise temperature of the antenna radiation resistance do not depends by the phisical temperature of the antenna but only by the noise temperature emitted by the object that the main lobe of the antenna is looking. As an example, if you install a parabolic dish on the Nort Pool at very low temperature and a similar parabolic dish in the desert at the equator at high temperature and you point both the antennas toward the Sun than the received Sun Noise will be the same no matter the structural temperature of both dishes will be. Of coarse only the phisical temperature of the antenna preamplifiers and all the associated receivers phisical temperature must be the same. 73 de i8CVS Domenico - Original Message - From: Nick Pugh quadp...@bellsouth.net To: 'Nick Pugh' quadp...@bellsouth.net; amsat-bb@amsat.org Sent: Sunday, September 09, 2012 8:15 PM Subject: [amsat-bb] Re: e: Satellite technical question I am sorry I did not mean the physical temperature What I wanted is the equivalent noise temperature. Thanks for those who replied nick -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Nick Pugh Sent: Sunday, September 09, 2012 10:07 AM To: amsat-bb@amsat.org Subject: [amsat-bb] e: Satellite technical question e: Satellite technical question Assume a cubesat with a monopole ¼ wave antenna at 400 mhz. The satellite is in full sun with a 500km orbit. What is the antenna temperature in full sun and in eclipse? TNX in advance Nick CAPE Team ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: AMSAT-UK Symposium streaming this year?
Hi, The BATC team will be there and will be making recordings of the presentations. At the present time we are uncertain about live streaming as we are uncertain about the quality of the hotels internet access. If its good, then we will stream, otherwise we will try and upload to the server asap after each presentation finishes. 73s Jim G3WGM -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Alan P. Biddle Sent: 11 September 2012 14:07 To: AMSAT-BB Subject: [amsat-bb] AMSAT-UK Symposium streaming this year? Hi, In the past, BATC has streamed the symposium. Will they be doing so this year? Alan WA4SCA --- We haven haven't got the money, so we we've got to think. Lord Rutherford ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Camera on antenna
- Original Message - From: Louis McFadin w5...@mac.com To: amsat-bb@amsat.org Sent: Wednesday, September 12, 2012 3:37 AM Subject: [amsat-bb] Re: Camera on antenna I use a camera mounted on the support strut of the dish feed. It is pointed at the center of the dish. Then I simply point the dish at the sun and make corrections to az and el until the shadow is exactly in the center of the dish. Then use those corrections in MacDoppler. Works great! No risk to the camera by looking at the sun. Lou McFadin W5DID w5...@cfl.rr.com Hi Lou, W5DID Using the Sun light and point a camera on the Sun is not a good procedure to calibrate the pointing of a dish for radio frequency signals because it is possible that the radio frequency feed is mounted shifted a fraction of degree making a big unwanted squint angle. Depending on the squint angle of the radio frequency feed with respect to the dish focal point it make a wrong pointing so that using the Sun light and a camera you believe that your dish is looking exactly at the Sun but in reality it can be not exactly pointed to get a radio frequency signal source like the Sun Noise. Particularly using large high gain dishes with sharp radiation lobe the correct procedure is to calibrate the pointing vector of the dish to the Sun using the Sun Noise and not a camera pointed to the Sun light. The correct procedure is to use the Sun Noise to calibrate antennas and Sun light to calibrate optical telescopes. Also to work EME with high gain dishes with narrow main lobe the Azimut and Elevation indication must be made not using position potentiometers but more sophisticated and precision devices like position resolvers, or position absolute encoders or selsyn indicators who permits high and constant resolution of fraction degrees for many years. For my 1.2 meters dish at 2.4 and 10.5 GHz I use not position potentiometers but 2 surplus position selsyn motors originally used to point guns on board of ships during the WWII 73 de i8CVS Domenico ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] 1962-09-12: JFK's Challenge
http://www.nasa.gov/multimedia/videogallery/index.html?media_id=151776051 73s Bernhard VA6BMJ @ DO33FL ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: 1962-09-12: JFK's Challenge
Thank you for the link. I have read JFK's speech before, but never seen the delivery. A great man. I was 8 years old when he was murdered. I was making Christmas decorations with my mother in the kitchen, we had no money for decorations so we were cutting out silver stars from the foil tops of milk bottles. She cried, and told me he was a good man, and so, did I. My father, a police officer (later GW1MLA, SK), a few days after watched the Jack Ruby incident, and said, that was wrong, too. 73 de andy g0sfj ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: AMSAT-UK Symposium streaming this year?
Hi Jim, I am sure I am expressing the views of the many who would dearly like to attend but can't due to personal circumstances. The live stream is a great way for us to have some involvement, the emphasis being on live. Of course the recorded stream will be welcome but hope for the live experience. Wishing all a great Symposium. 73 John G7HIA From: Jim List jiml...@milnet.uk.net To: apbid...@mailaps.org; 'AMSAT-BB' amsat-bb@amsat.org Sent: Wednesday, 12 September 2012, 10:23 Subject: [amsat-bb] Re: AMSAT-UK Symposium streaming this year? Hi, The BATC team will be there and will be making recordings of the presentations. At the present time we are uncertain about live streaming as we are uncertain about the quality of the hotels internet access. If its good, then we will stream, otherwise we will try and upload to the server asap after each presentation finishes. 73s Jim G3WGM -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Alan P. Biddle Sent: 11 September 2012 14:07 To: AMSAT-BB Subject: [amsat-bb] AMSAT-UK Symposium streaming this year? Hi, In the past, BATC has streamed the symposium. Will they be doing so this year? Alan WA4SCA --- We haven haven't got the money, so we we've got to think. Lord Rutherford ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: swr explained
Nick, Thanks for sharing! Very cool video. I have never seen wave theory demonstrated with such clarity. Andy ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: swr explained
At 09:36 PM 9/12/2012 +, kn...@hotmail.com wrote: Nick, Thanks for sharing! Very cool video. I have never seen wave theory demonstrated with such clarity. Andy No No No, Here's SWR Properly explained, Laymans terms: http://www.youtube.com/watch?v=zOOihiLLS4Ifeature=related ;-) KB7ADL ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] NASA TV to Show 3 Hams Return to Earth on Sunday, September 16
Hello everyone, Here is some news that is best sent before the weekend ANS is released. Check out the Three Hams Return to Earth this Weekend; Watch Live on NASA TV link on http://www.arrl.org/ for information about NASA TV coverage on Sunday, September 16. -- 73 de JoAnne K9JKM k9...@amsat.org Editor, AMSAT News Service Associate Editor, AMSAT Journal ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
