| 摘要 |
PURPOSE:To compensate average level variation even when variation in frequency in a transmission band is not uniform by using a spread spectrum signal which is spread uniformly in the transmission band as a monitor signal and controlling the gain of a receiving amplifier according to the level of the monitor signal obtained by demodulating the spectrum spread signal. CONSTITUTION:The monitor signal 6 which has a narrow-band signal spectrum as shown in a figure A is multiplied and modulated with a PN system signal which has a high clock frequency to obtain the spectrum spread signal 6 whose spectrum is spread over a wide frequency band shown in figure B. Then, the spread spectrum signal 6 is superposed upon a carrier inhibiting single-side-band transmission signal and sent out to a transmission line and a reception side performs correlation detection to sum up voltages of signals of respective spectrum components of the spread spectrum signal 6, thereby modulating the signal into the monitor signal having a narrow-band signal spectrum shown in figure A. |
