Could the data rate be enhanced used antenna arrays?, JPL Performs First Two-Antenna Uplink Experiment |
Could the data rate be enhanced used antenna arrays?, JPL Performs First Two-Antenna Uplink Experiment |
Mar 22 2006, 11:54 PM
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Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
Interesting announcement on using antenna arrays for uploading data:
http://www.jpl.nasa.gov/news/features.cfm?feature=1057 JPL Performs First Two-Antenna Uplink Experiment Carolina Martinez/JPL (818) 354-9382 March 21, 2006 For the first time ever, NASA's Deep Space Network has used a pair of smaller antennas to successfully send two simultaneous signals to a spacecraft in deep space that were combined at the spacecraft to yield greater signal power. Prior to this experiment, only single 34-meter (111- foot) or 70-meter (230-foot) antennas had been used to uplink signals. This is a significant first step for future uplink capabilities using multiple antennas known as arrays. The recent experiment combined X-band signals from two 34-meter (111-foot) antennas at the Goldstone complex near the Mojave Desert, and transmitted the combined signal to NASA's Mars Global Surveyor spacecraft currently orbiting Mars. The Mars Global Surveyor spacecraft received the combined signal, measured the combined power levels, and verified the predicted power gain, as a result of the combining operation. The Deep Space Network provides the two-way communications link that guides and controls spacecraft and returns images and other scientific data to Earth. Currently, each Deep Space Network facility has one antenna of 70-meter (230-foot) diameter, between two and seven 34-meter (111-foot) antennas, and one 26-meter (85-foot) antenna. There are three deep-space communications complexes placed approximately 120 degrees apart around the world: at Goldstone in California's Mojave Desert; near Madrid, Spain; and near Canberra, Australia. This configuration ensures that an antenna is always within sight of a given spacecraft, day and night, as Earth rotates. Although previously downlink arraying has been performed, the lack of a demonstrated ability to perform uplink arraying has limited the potential use of antenna arrays. Antenna arrays have the potential to create an equivalent very large antenna aperture by combining many smaller antennas. The successful demonstration of uplink arraying is significant because it removes a serious obstacle to moving towards an operational arrayed network for space communications, one that can be used for both uplink and downlink. For the technical write up on the experiment see: http://deepspace.jpl.nasa.gov/dsn/features/uplink.html . -------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Mar 23 2006, 05:33 AM
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Member Group: Members Posts: 356 Joined: 12-March 05 Member No.: 190 |
10 KW transmitting dish? wow. wouldn't want to be a bird flying over that when its on! maybe the intensity isn't that bad though....big dishes after all
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Jun 22 2006, 04:19 AM
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Newbie Group: Members Posts: 1 Joined: 22-June 06 Member No.: 922 |
10 KW transmitting dish? wow. wouldn't want to be a bird flying over that when its on! maybe the intensity isn't that bad though....big dishes after all The DSN antennas actually transmit commands routinely at 20kW. The 70m dish at Goldstone California is spec'd for 400kW S-band and 500kW X-band for radar imaging. See: http://www331.jpl.nasa.gov/group8/ |
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Guest_Richard Trigaux_* |
Jun 22 2006, 07:40 AM
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Guests |
10 KW transmitting dish? wow. wouldn't want to be a bird flying over that when its on! maybe the intensity isn't that bad though....big dishes after all Not a problem for birds flying above the dish, as the power is divided by he surface. But a bird flying under the emitting horn at the focal point of the dish will be in trouble. I hope there are some protections. |
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Jun 22 2006, 08:08 AM
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Junior Member Group: Members Posts: 22 Joined: 2-March 06 Member No.: 691 |
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Jun 23 2006, 10:08 AM
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
Eagles may soar, but Weasles don't get sucked into airplane engines.
The important thing about uplink arraying is it can save chronically inadequate 70 meter dish time for missions that really need it. If you don't have to use a 70 meter dish for improving on a slightly marginal communications uplink, you're ahead in data return and DSN scheduling |
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