FIELD: physics.
SUBSTANCE: invention relates to promising composite systems with a fibre-terrestrial structure, typical representatives of which are the fast developing Radio-over-Fibre (RoF) local distribution systems, and can be used in a base station of such a system. A heterodyne signal is generated using the effect of period doubling when modulating a powerful sinusoidal signal, wherein besides the fundamental modulation frequency F and its higher harmonics, subharmonics and products of their mixing with the fundamental frequency and harmonics appear in the radiation spectrum. In the module for realising the method, the heterodyne signal is generated onsite from the return channel signal received by the base station using the above-mentioned effect. The circuit includes an antenna 18, a subharmonically pumped mixer 19, a band-pass filter 20, an amplifier 21, a directional coupler 22, a first laser 23, a second laser 24, a photodiode 25, an amplifier 26 and a modulation-eliminating unit for restoring the carrier frequency 27.
EFFECT: simplification of the circuit of the base station without complication of the circuit of the central station and design of a separate optical channel for transmitting a heterodyne signal, less stringent requirements for frequency stability of the local heterodyne signal.
2 cl, 4 dwg
