Protection switching system for microwave radio

• US 4,039,947 A
• Filed: 06/29/1976
• Issued: 08/02/1977
• Est. Priority Date: 06/29/1976
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Miedema, Hotze
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/700,833
• Time in Patent Office: 399 Days
• Field of Search: 325/2, 325/3, 325/5, 325/40, 325/52, 325/65, 325/156, 325/158, 343/200, 343/205-208, 340/147 SC
• US Class Current: 455/8
• CPC Class Codes: H04B 1/74 for increasing reliability, e.g. using redundant or spare channels or apparatus replacing by standby devices for amplifiers H03F1/52, H03F1/542

Abstract

A protection switching system for microwave radio employs a frequency-agile-repeater (FAR) which is automatically re-tuned to the frequency of a failed repeater. A shutter associated with the failed repeater reflects the input signal normally employed by the failed repeater into the FAR, while the output of the FAR is reflected by a second shutter into the transmitting antenna.

Claims

1. An improved microwave protection switching system of the type that includes:

a receiving antenna;

a transmitting antenna;

a plurality of channel-separating networks connected to said receiving antenna;

a plurality of channel-combining networks connected to said transmitting antenna; and

a corresponding plurality of microwave repeaters respectively interconnecting said channel separating and channel-combining networks, each of said repeaters being tuned to a uniquely assigned pair of transmitting and receiving frequencies, wherein the improvement comprises;

a corresponding plurality of remotely operable input and output shutters respectively associated with the input and output circuits of said microwave repeaters;

a frequency-agile-repeater remotely tunable to any of said pairs of frequencies;

means for connecting said frequency-agile-repeater to said receiving and transmitting antennas;

first means for monitoring the performance of each of said microwave repeaters and for generating a first alarm signal when any one of said repeaters fails or becomes marginal; and

means, responsive to said first alarm signal, for closing the input and output shutters associated with the failed repeater and for simultaneously re-tuning said frequency-agile-repeater to the transmitting and receiving frequencies of said failed repeater, whereby the microwave signal normally repeatered by the failed repeater is repeatered by said frequency-agile-repeater.

2. The system according to claim 1 wherein said connecting means comprises:

a first, three-port circulator connected between said receiving antenna and said channel separating networks;

a second, three-port circulator having one port connected to said first circulator, a second port connected to the input circuit of said frequency-agile-repeater, and a third port terminated in a resistor;

a third, three-port circulator connected between said channel-combining networks and said transmitting antenna; and

a fourth, three-port circulator having one port connected to said third circulator, a second port connected to the output circuit of said frequency-agile-repeater and a third port terminated in a resistor.

3. The system according to claim 1 further comprising:

a space diversity receiving antenna;

a second plurality of channel separating networks connected to said space diversity antenna;

a second plurality of remotely operable input shutters respectively connected to said second plurality of channel separating networks;

a plurality of remotely operable switches for selectively associating a particular repeater with either said antenna or said space diversity antenna;

second means for monitoring the performance of each of said microwave repeaters and for generating a second alarm signal when the level of the signal applied to the input thereof falls below some predetermined threshold;

means responsive to said second alarm signal for activating the corresponding one of said plurality of remotely operable switches; and

means for selectively connecting said frequency-agile-repeater to said space diversity antenna.

4. The system according to claim 3 wherein said selective connecting means comprises:

a fifth, three-port circulator connected between said space diversity antenna and said second plurality of channel separating networks;

a sixth, three-port circulator having a first port connected to said fifth circulator, a second port, and a third port terminated in a resistor; and

switching means, connected to and controlled by said shutter closing means, for selectively connecting the input of said frequency-agile-repeater to the second port of either said sixth or said second circulator.

5. The system according to claim 1 wherein said receiving and transmitting antennas respectively receive and transmit microwave energy in first and second polarizations, said channel separating networks, channel-combining networks, microwave repeaters, input and output shutters, connecting means, monitoring means and shutter closing means are replicated for both of said polarizations;

and said system further comprises;

means for switching and frequency-agile-repeater between the connecting means associated with said first and said second polarizations.

6. An improved microwave transmission system of the type that comprises:

a first main station including a microwave transmitting antenna and a plurality of microwave transmitters each operating at a different frequency connected to said antenna;

a second main station including a microwave receiving antenna and a plurality of microwave receivers each operating at a different frequency connected to said antenna; and

at least one repeater station intermediate said first and second main stations, said repeater station including a microwave receiving antenna, a microwave transmitting antenna, and a plurality of microwave repeaters connected to said receiving and transmitting antennas, each repeater being tuned to the frequency of the corresponding transmitter and receiver in said first and second main stations, respectively, wherein the improvement comprises;

means for detecting the failure of any one of said plurality of transmitters;

a frequency-agile-transmitter;

means, responsive to said detecting means, for shuttering the output of said failed transmitter and for re-tuning said frequency-agile-transmitter to the transmitting frequency of the failed transmitter;

means, responsive to said detecting means, for associating the input signal normally connected to the input of the failed repeater with the input of said frequency-agile-transmitter; and

means, responsive to said detecting means, for associating the output of said frequency-agile-transmitter with said transmitting antenna.

7. An improved microwave transmission system of the type that comprises:

a first main station including a microwave transmitting antenna and a plurality of microwave transmitters each operating at a different frequency connected to said antenna;

a second main station including a microwave receiving antenna and a plurality of microwave receivers each operating at a different frequency connected to said antenna; and

at least one repeater station intermediate said first and second main stations, said repeater station including a microwave receiving antenna, a microwave transmitting antenna, and a plurality of microwave repeaters connected to said receiving and transmitting antennas, each repeater being tuned to the frequency of the corresponding transmitter and receiver in said first and second main stations, respectively, wherein the improvement comprises;

means for detecting the failure of any one of said plurality of receivers;

a frequency-agile-receiver;

means, responsive to said detecting means, for shuttering the input to said failed receiver and for re-tuning said frequency-agile-receiver to the receiving frequency of the failed receiver;

means, responsive to said detecting means, for associating the output circuit normally connected to the output of the failed receiver with the output of said frequency-agile-receiver; and

means, responsive to said detecting means, for associating the input of said frequency-agile-receiver with said receiving antenna.

8. An improved microwave transmission system of the type that comprises:

a first main station including a microwave transmitting antenna and a plurality of microwave transmitters each operating at a different frequency connected to said antenna;

a second main station including a microwave receiving antenna and a plurality of microwave receivers each operating at a different frequency connected to said antenna; and

at least one repeater station intermediate said first and second main stations, said repeater station including a microwave receiving antenna, a microwave transmitting antenna, and a plurality of microwave repeaters connected to said receiving and transmitting antennas, each repeater being tuned to the frequency of the corresponding transmitter and receiver in said first and second main stations, repectively, wherein the improvement comprises;

means for detecting the failure of any one of said plurality of repeaters;

a frequency-agile-repeater;

means, responsive to said detecting means, for shuttering the input and the output of the failed repeater and for re-tuning said frequency-agile-repeater to the transmitting and receiving frequencies of the failed repeater; and

means, responsive to said detecting means, for associating the input and output of said frequency-agile-repeater with said receiving and transmitting antennas, respectively.