MICROWAVE RELAY SYSTEM HAVING AUXILIARY SIGNAL TRANSMISSION ARRANGEMENT

• US 3,860,870 A
• Filed: 01/09/1974
• Issued: 01/14/1975
• Est. Priority Date: 01/12/1973
• Status: Expired due to Term

• Current Assignee: Tadashi Furuya
• Original Assignee: Tadashi Furuya
• Inventors: Furuya, Tadashi
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Libman, George H.
• Application Number:
  US05/432,113
• Time in Patent Office: 370 Days
• Field of Search: 325/1,3,9-11,13,61,7 179/15BD,15FE,15AD,15BM
• US Class Current: 370/204
• CPC Class Codes: H04B 17/0087 using auxiliary channels or channel simulators

Abstract

A microwave heterodyne relay system transmitting a main carrier, angle-modulated wave in combination with an auxiliary signal transmission system is disclosed. The auxiliary signal transmission is accomplished by a subcarrier wave frequencymodulated with the auxiliary signal. The frequency-modulated subcarrier wave is then used to amplitude modulate the main carrier. The receiver of the relay system is branched into two paths. In the first path, the envelope of the main carrier is detected and then frequency demodulated to obtain the auxiliary signal. In the second path, the amplitude modulation of the main carrier is suppressed by an amplitude limiter before the main carrier is amplitude modulated by the locally generated frequency-modulated subcarrier wave prior to retransmission.

Claims

1. A microwave heterodyne relay system having a plurality of relay stations each having a transmitting and receiving means for relaying a main carrier wave angle-modulated with a main base band signal, said transmitting and receiving means in at least one relay station including an auxiliary signal transmission means comprising:

transmitting means for said auxiliary signal consisting of;

means for generating a subcarrier wave so selected as to be disposed outside the uppermost component of said base band, means for frequency-modulating said subcarrier wave with an auxiliary signal, and means for amplitude-modulating said main carrier wave with said frequency-modulated subcarrier wave;

receiving means for said auxiliary signal consisting of;

branching means for receiving said main carrier wave amplitudemodulated with said subcarrier wave and for dividing its output signal into two paths, means for envelope-detecting one of the branched components of said main carrier wave and for extracting said subcarrier wave frequency-modulated with said auxiliary signal, and means for frequency-discriminating said extracted subcarrier wave so as to demodulate said auxiliary signal; and

amplitude limiting means consisting of;

means for receiving the other of said branched components of the main carrier wave and for suppressing amplitude variation of said received amplitude-modulated main carrier wave, and means for applying said amplitude-limited main carrier wave to the input of said amplitude-modulating means.

2. In the microwave heterodyne relay system as recited in claim 1 wherein said transmitting and receiving means includes a receiving antenna for receiving said main carrier wave, first convertor means connected to said receiving antenna for converting said main carrier wave to an intermediate frequency signal, intermediate amplifier means for amplifying said intermediate frequency signal, second convertor means receiving the amplified intermediate frequency signal and converting it to a transmitting frequency signal, amplifier means for amplifying said transmitting frequency signal, and a transmitting antenna for radiating the amplified transmitting frequency signal, said branching means being part of said intermediate amplifier means, and said amplitude limiting means being connected between said intermediate amplifier means and said second convertor means.

3. In the microwave heterodyne relay system as recited in claim 2, said means for amplitude-modulating being connected between said second convertor means and said amplifier means.

4. In the microwave heterodyne relay system as recited in claim 2, said means for amplitude-modulating being connected between said amplitude limiting means and said second convertor means.