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Polar Radar for Ice Sheet Measurements

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Home>PRISM Update>Radar Team>Bistatic radar will partially counteract...


Bistatic radar will partially counteract the specular effect of the water layer on the bedrock.

Picture of John Paden  



Part One of Two

Audio version - Part 1 (6.14 MB) - .wav format
Video version - Part 1 (10.4 MB) - .mov format

Part Two of Two

Audio version - Part 2 (11 MB) - .wav format
Video version - Part 2 (18.7 MB) - .mov format
Speaker: John Paden, graduate student, EECS, University of Kansas, 2002.

Modified Part One Transcript: Our radar will be capable of operating in monostatic mode or bistatic mode. Most radars that you hear about operate in monostatic mode. People don't even mention that it is monostatic radar because it is so common. The reason bistatic mode is so rare is that it makes things much more difficult. And that is one of the things that makes our radar special, we are going to be using that to our advantage. It makes the system more complex, but we are going to get something from the complexity.

Modified Part Two Transcript: One of the main differences between monostatic and bistatic radar is that in monostatic radar your transmitter and receiver are in the same position. This allows two different ways for the data to be sent from the transmitter to the receiver. One information path is through the transmitted wave form being reflected off whatever you are looking at and coming back to the receiver. This path of the reflection is called the measurement path. The other information path is through a cable linking the transmitter and the receiver together. This cable makes it very easy to synchronize the transmitter and the receiver with each other. In the case of bistatic radar, the transmitter and receiver are quite a distance apart, so you can't just put a cable between them. The synchronization has to occur only through the measurement path. You are actually trying to synchronize from the information that you have gleaned from the received signal, so it's quite a bit more difficult. Ice attenuates the radar signal. If you have an FM station, which operates at about the frequencies that we will use, whose signal had to travel through ice instead of air, you would find that the radio waves wouldn't propagate nearly as far. Instead of being able to hear your radio station hundreds of kilometers away, you would have to be within a few kilometers of the radio station. So there is significant attenuation due to the ice.

In addition, the warmer the ice is, the more it dampens the signal. So we need to take our measurements as early in the summer as possible when the temperature is above negative forty degrees Celsius, but below zero degrees Celsius. This is probably the best time to be imaging with our radar because then the ice doesn't dampen the signal as much.


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