Satellite switching system

• US 4,144,495 A
• Filed: 02/23/1977
• Issued: 03/13/1979
• Est. Priority Date: 02/23/1977
• Status: Expired due to Term

• Current Assignee: COMSAT Corporation (Reorganized ISA SA)
• Original Assignee: Communications Satellite Corporation (Reorganized ISA SA)
• Inventors: Metzger, Sidney
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Blum, T. M.
• Application Number:
  US05/773,862
• Time in Patent Office: 748 Days
• Field of Search: 343/100 ST, 325/3, 325/4, 325/14
• US Class Current: 455/17
• CPC Class Codes: H04B 7/2045 SS-FDMA, FDMA satellite switching

Abstract

A multi-beam satellite switching system employs onboard switching for the purpose of increasing the up path and down path antenna gains. A multiplicity of up path antenna beams and of down path antenna beams (not necessarily the same number of each direction) are provided by the system. A number of amplifier systems are distributed across the frequency band of interest. These amplifier systems comprise input amplifiers including filters, frequency converters and output amplifiers. A switching and control circuit accepts an up path signal from only the desired input amplifier and connects the desired output amplifier to the desired down path beam. Each earth station transmits to the satellite a suitable signal to perform the desired switching functions.

Claims

1. A satellite system employing onboard switching comprising:

receiving antenna means for providing a multiplicity of up path antenna beams directed toward different areas on the ground,

a plurality of input amplifiers connected to said receiving antenna means for amplifying signals received in said multiplicity of up path antenna beams,

a plurality of output amplifiers,

input switch means for connecting the output of only one selected input amplifier to the input of an output amplifier,

transmitting antenna means for providing a multiplicity of down path antenna beams directed toward different areas on the ground,

output switch means for connecting the output of one or more selected output amplifiers to said transmitting antenna means to couple energy into one or more selected down path antenna beams, and

switch control means for controlling said input switch means and said output switch means whereby a desired up path antenna beam is connected through a selected output amplifier to a desired down path antenna beam.

2. A satellite system according to claim 1 wherein said switch control means comprises:

control signal detection means connected to said plurality of input amplifiers for detecting signals identifying desired up path and down path antenna beams, and

control logic means responsive to said control signal detection means for selectively energizing said input and output switch means corresponding to said desired up path and down path antenna beams.

3. A satellite system according to claim 1 further comprising a plurality of identical sets of input filters, each set of input filters being connected to the output of a corresponding one of said plurality of input amplifiers and each set of input filters consisting of a number of contiguous bandpass filters equal in number to the number of said output amplifiers, corresponding filters in each set of input filters being selectively connected to the input of a common output amplifier by said input switch means.

4. A satellite system according to claim 3 wherein control signals are transmitted within the bandwidths of each of said contiguous bandpass filters and said switch control means comprises:

control signal detection means connected to each of said contiguous bandpass filters in each set for detecting said control signals identifying desired up path and down path antenna beams, and

control logic means responsive to said control signal detection means for selectively energizing said input and output switch means corresponding to said desired up path and down path antenna beams.

5. A satellite system according to claim 4 wherein said control signals are frequency modulated by a first frequency of a first plurality of frequencies equal in number to the number of up path antenna beams and a second frequency of a second plurality of frequencies equal in number to the number of down path antenna beams, each said control signal detection means comprising:

a control frequency filter for passing the corresponding control signal transmitted within the bandwidth of the respective one of said contiguous bandpass filters,

a frequency discriminator connected to said control frequency filters for detecting said first and second frequencies, and

filter and detector means connected to said frequency disciminator for generating control pulses in response to said first and second frequencies.

6. A satellite system according to claim 5 wherein said control logic means comprises bistable multivibrator means set by said control pulses for providing switch control signals to said input and output switch means.

7. A satellite system according to claim 6 wherein said control signals are frequency modulated by a third frequency at the end of a data signal transmission and said filter and detector means is responsive to said third frequency to generate a reset pulse for said bistable multivibrator means.

8. A satellite system according to claim 4 wherein said control signals are pulse code modulated by a first code of a first plurality of codes equal in number to the number of up path antenna beams and a second code of a second plurality of codes equal in number to the number of down path antenna beams, each said control signal detection means comprising:

a control frequency filter for passing the corresponding control signal transmitted within the bandwidth of the respective one of said contiguous bandpass filters,

code detection means connected to said control frequency filter for detecting said first and second codes, and

decoder means connected to said code detection means for generating control pulses in response to said first and second codes.

9. A satellite system according to claim 8 wherein said control logic means comprises bistable multivibrator means set by said control pulses for providing switch control signals to said input and output switch means.

10. A satellite system according to claim 9 wherein said control signals are pulse code modulated by a third code at the end of a data signal transmission and said code detection means is responsive to said third code to generate a reset pulse for said bistable multivibrator means.

11. A satellite system according to claim 4 wherein said control logic means comprises bistable multivibrator means for providing switch control signals to said input and output switch means, said bistable multivibrator means being set by control pulses generated by said control signal detection means.

12. A satellite system according to claim 11 wherein said control signals include a measure of time for the duration of the transmission, said control signal detection means including reset means for resetting said bistable multivibrator means, after the time for the duration of the transmission has elapsed.

13. A satellite system according to claim 3 wherein the number of output amplifiers is equal to the number of up path antenna beams.

14. A satellite system according to claim 3 wherein the number of output amplifiers is less than the number of up path antenna beams.