Impulse response measurements over space-earth paths using the GPS coarse/acquisition codes

The impulse responses of radio transmission channels over space–earth paths were measured using the coarse/acquisition code signals from the Global Positioning System of satellites. The data acquisition system and signal processing techniques used to develop the impulse responses are described. Examples of impulse response measurements are presented. The results indicate that this measurement approach enables detection of multipath signals that are 20 dB or more below the power of the direct arrival. Channel characteristics that could be investigated with additional measurements and analyses are discussed.