Abstract: Suitable gain control is achieved at low cost. In a receiving apparatus, an RF signal that is amplified by an RF amp is converted to an IF frequency by a frequency conversion unit and amplified by an IF amp, then the output signal from the IF amp that was converted to a digital signal by an ADC is inputted to a digital processing unit. The output from the ADC is then filtered to a desired frequency by a digital filter and inputted to the digital processing unit. In the digital processing unit the signal power before filtering by the digital filter and the signal power after filtering by the digital filter are measured, and the power difference is calculated. Based on the power difference, which indicates the ratio of unnecessary power, the digital processing unit controls the gain ratio of the RF amp and IF amp.

Abstract: Suitable gain control is achieved at low cost. In a receiving apparatus, an RF signal that is amplified by an RF amp is converted to an IF frequency by a frequency conversion unit and amplified by an IF amp, then the output signal from the IF amp that was converted to a digital signal by an ADC is inputted to a digital processing unit. The output from the ADC is then filtered to a desired frequency by a digital filter and inputted to the digital processing unit. In the digital processing unit the signal power before filtering by the digital filter and the signal power after filtering by the digital filter are measured, and the power difference is calculated. Based on the power difference, which indicates the ratio of unnecessary power, the digital processing unit controls the gain ratio of the RF amp and IF amp.