Video signal distribution system microwave radio link for transmitting double sideband phase modulated carrier signal

• US 5,619,248 A
• Filed: 06/17/1994
• Issued: 04/08/1997
• Est. Priority Date: 07/06/1993
• Status: Expired due to Fees

• Current Assignee: MCEL PLC, EEV Ltd. (Teledyne Technologies Incorporated)
• Original Assignee: MCEL PLC, Plessey Semiconductors Limited (Plessey Group Holdings Ltd.)
• Inventors: Hobden, Mervyn K., Rhodes, deceased, John G. L., Turner, executor, Ronald, Spencer, David G.
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US08/261,401
• Time in Patent Office: 1,026 Days
• Field of Search: 348/6, 348/724, 455/3.1, 455/6.1, 455/46, 455/110
• US Class Current: 725/73
• CPC Class Codes: H04N 7/20 Adaptations for transmission via a GHz frequency band, e.g. via satellite

Abstract

In a video signal distribution system in which a plurality of video signals are modulated onto individual carrier signals spaced over a band of frequencies to form a composite signal for transmission over cables of the system, a point-to-point radio link forming part of the distribution system is provided in which the composite signal is transmitted as double side band phase modulation of a single microwave carrier signal.

Claims

1. A video signal distribution system for transmitting a wide-band composite signal having a plurality of video signals modulated on respective sub-carriers of respective different frequencies spaced over a band of frequencies, said distribution system comprising:

a microwave point-to-point radio link having a transmitter arrangement including means for amplitude modulating said composite signal onto a microwave carrier frequency signal having a relative phase and amplitude to provide a double-sideband suppressed carrier amplitude modulated signal, means for combining said modulated signal with a carrier frequency reference signal, and means for adjusting the relative phase and amplitude of said microwave career frequency signal and said reference signal to provide a double side-band phase modulated carrier signal for transmission over said microwave radio link.

2. The video signal distribution system in accordance with claim 1 wherein said reference signal is in phase quadrature with said microwave carrier frequency signal.

3. The video signal distribution system in accordance with claim 1 wherein said double side-band phase modulated carrier signal has an amplitude, and wherein said means for adjusting the relative phase and amplitude of said microwave carrier frequency signal and said reference signal is responsive to the amplitude of said double side-band phase modulated carrier signal.

4. A wide-band microwave modulator arrangement for a video signal distribution system, comprising:

a microwave carrier signal source, means for directing signals from said source over a first path including phase shift means and a balanced amplitude modulator arrangement and over a second path including phase adjusting means, means for applying video signals to a modulating input of said modulator arrangement, means for combining signals from outputs of said first and second paths to provide substantially phase modulated output signals, and means responsive to the amplitude of said phase modulated output signals for providing a phase adjusting signal to said phase adjusting means in said second path.

5. A wide-band microwave modulator arrangement for a video signal distribution system, comprising:

a microwave carrier signal source, means for directing signals from said source over a first path including phase shift means and a balanced amplitude modulator arrangement and over a second path including phase adjusting means, and means for combining signals from the outputs of said first and second paths to provide substantially purely phase modulated output signals.