| 摘要 |
PCT No. PCT/FI96/00037 Sec. 371 Date Sep. 18, 1997 Sec. 102(e) Date Sep. 18, 1997 PCT Filed Jan. 17, 1996 PCT Pub. No. WO96/22540 PCT Pub. Date Jul. 25, 1996A receiver for spectrum analysis includes at least one mixer in which a radio frequency input signal to be measured is mixed with an oscillator frequency generated by a voltage-controlled oscillator. In a detector, the level of an input signal to be measured is detected, after the signal has been transferred onto a lower frequency. The use of a logarithmic amplifier may be avoided by directing the detected signal to a decision means, which, in response to a change in the level of the detected input signal, provides a control voltage proportional to the magnitude and the direction of the change. The voltage commands an adjustable attenuator to attenuate the signal to be measured so that the level of the detected input signal substantially remains constant. The attenuation of the attenuator measured in decibels is linearly dependent on the control voltage, so that the values of the control signal directly represent the amplitude values. |
