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Polar Radar for Ice Sheet Measurements

curved ice line
jagged ice
Home>PRISM Update >Overview 2004

Radar Overview 2004 - Ultrawideband Accumulation Radar


  • Maps internal layers to a depth of 200 m with 10 cm resolution
  • Generates an extremely linear chirp signal with minimum variation in transmit power for improved sidelobe performance
  • Fast sweep rate.
  • Compact PCI form factor

System Specifications:

Frequency 500-2000 MHz
Sweep Time 4 ms
PRF 200 Hz
Transmit Power 100 mWatt
Number of Coherent Integrations 60
Antennas TEM Horn
A/D Dynamic Range 12-bit, 72 dB
Sampling Rate 10 MHz

System Overview

schematic of modules of ultrawideband radar

The system has 5 modules, as follows:

  • A Phase-Locked Loop system to generate the transmit signal.
  • An Automatic Gain Control system to level the transmit power.
  • A Phase-Locked Oscillator system to down convert the transmit signal.
  • An RF receiver board.
  • An IF receiver board (to match the received signal to the dynamic range of the A/D converter)


FM-CW Radar Principles

In FM-Cw radar, a chirp signal is transmitted, hits a target and is mixed with the transmit signal. If many targets are present, the IF signal will be a superposition of many signals at different beat frequencies. The beat frequency is B_/T and the resolution is c/2B.

illustration of signal in graphic format

The entire operational radar fits on one aluminum compact PCI card and is placed in a compact PCI case along with the data acquisition systems and the WCORDS system.

PCI board with wires and computer boards

Delay Line Test

Corrected Spectrum (Blue) vs. Ideal Spectrum (Red) after removing the delay line effects and the system effects.

blue line is more spread out than red line, but amplitudes match closely

Radar In Action - 2004 Field Experiment

team standing by horn antenna and Tucker vehicle
Close up of TEM Horn Antenna


snow stratigraphy from 0-30 meters depth
snow stratigraphy from 100-140 m
snow/ice stratigraphy from 250-280 m

Internal layers were successfully mapped at both NGRIP (2003) and Summit (2004), Greenland with high resolution to a depth of 200 m.

The water-equivalent accumulation rate at Summit was determined to be 36 cm/yr.





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