| 摘要 |
PURPOSE:To make a transmitter-receiver excellent in noise resistant characteristic anti-interference characteristic and privacy corresponding to a narrow spread band width caused by 2-wave transmission of the reference signal transmission system and also easy in data reproduction. CONSTITUTION:As to output signals of 1st and 2nd local oscillators 1, 2 whose frequency difference is d.k+d/2, where d is a data band width and k is a positive integer, the former are modulated by a 1st multiplier 4 and the frequency is spread by a spread code generator 3 and a 2nd multiplier 5, the latter is frequency-spread by a spread code generator 3 and a 2nd multiplier 5 and they are synthesized by an adder 7 to generate a transmission signal. The transmission signal passes through a 1st band pass filter 8 at the receiver side and squared by a square computing element 9 and its output is given to a 2nd band pass filter 10, in which a frequency difference (F2-F1) of two waves is extracted and data are reproduced to attain bands of two waves in existence in duplicate. |
