Experimental parameters affecting amplitude scintillation measurements on satellite links

The influence of the duration of the basic measuring interval (BMI) and the sampling rate (integration time) on the determination of the variance of amplitude deviations from their clear weather mean was studied theoretically and experimentally, using amplitude scintillation recordings of the TM beacon of the OTS satellite. The error in the determination of the variance was found to depend strongly on the integration time (IT). For an IT of 100 ms (sampling rate 10 Hz), an error below 3 percent could be determined for the highest measured corner frequencies f sub c. Since f sub c increases as the square root of f (where f is the carrier frequency), the sampling rate should be even higher for scintillation measurements at higher frequencies (e.g., the Olympus experiment at 30 GHz). It is concluded that, under the given experimental conditions, a sampling interval of 100 ms and a BMI of about 1 min proved to be appropriate to keep errors low in determining the variance.