SATELLITE COMMUNICATION SYSTEM

• US 3,710,255 A
• Filed: 03/21/1969
• Issued: 01/09/1973
• Est. Priority Date: 03/21/1969
• Status: Expired due to Term

• Current Assignee: Francis A. Gicca
• Original Assignee: Francis A. Gicca
• Inventors: Gicca, Francis A.
• Primary Examiner(s): Richardson, Robert L.
• Assistant Examiner(s): Lange, Richard P.
• Application Number:
  US04/809,175
• Time in Patent Office: 1,390 Days
• Field of Search: 325/4,9,11,55 179/15BS,15BA,15FE 343/1ST 179/15S
• US Class Current: 455/13.1
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays

Abstract

An improved communication system using an active transponder to relay microwave signals from any one of a number of transmitting stations to selected groups of receiving stations. In a preferred system the active transponder is installed in a satellite spacecraft and is arranged to convert a number of signals, in closely spaced channels, from the transmitting stations in such a manner that the bandwidth of each one of the relayed signals is increased and retransmitted without suffering from the effects of interchannel modulation.

Claims

1. A transponder, for use in a multichannel FM communication system to relay simultaneously received transmission having different carrier frequencies from any one of plurality of transmitters to any one of a plurality of receivers, comprising. a. receiving antenna means for receiving transmission from any one oF the transmitters on any channel;

b. first filter means connected to receiving antenna means including a plurality of set of band-pass filters each thereof having a different center pass frequency;

c. heterodyning means consisting of a first and second local oscillator each producing a signal output and a first and second sets of mixing means each mixing means of each set responsive to the signal output of the first and second local oscillator and the carrier frequency signals of the first filter means to produce at least two sets of difference frequency signals having similar carrier frequencies, each one thereof carrying the deviation signal of a corresponding channel;

d. multiplying means operative on each one of the disparate difference frequencies signals to shift the frequency within the band of frequencies acceptable to the receivers and to increase the deviation of each one of the so-changed signals; and

e. transmitting antenna means selectively energized and oriented to separate mutually interfering ones of the so-changed signals of the multiplier means and to direct such separated signals to different ones of the receivers.

2. A transponder as in claim 1 having, additionally, second filter means disposed between the heterodyning means and the multiplying means, each such second filter means passing a single one of the difference frequency signals out of the first and the second mixing means.

3. A transponder as in claim 2 wherein the multiplying means includes a separate multiplier for each one of the difference frequency signals, each such multiplier being operative on both the carrier frequency signal and the deviation signal of each one of the difference frequency signals.

4. A transponder as in claim 2 having, additionally, third filter means operative on the output signals of each one of the multiplying means to pass only a single one of the signals out of each one of the multiplying means.

5. A transponder as in claim 4 having, in addition, amplifying means operative on each one of the signals out of the third filter means.

6. A transponder as in claim 5 having, in addition, fourth filter means disposed between the amplifier means and the transmitting antenna means, each such filter means operative on the output signals from the amplifier means to pass only a single one of the output signals to the transmitting antenna means.

7. An improved communication system for transmitting information through a transponder in a synchronous communication satellite, from a transmitter at a ground station to receivers at ground stations in different geographical areas, the transmitter being adapted to impress information to be transmitted as a modulation signal on any selected one of a plurality of different uplink frequency signals within a fixed bandwidth, such system being characterized by:

a. n sets of filtering and heterodyning means in the transponder, each set thereof being responsive to uplink frequency signals from the transmitter, within a different one of n portions of the fixed bandwidth, for converting the uplink frequency signals to m sets of identical intermediate frequency signals;

b. n sets of frequency multiplying means in the transponder, each one of such means being responsive to a different one of the n sets of intermediate frequency signals, for producing n sets of downlink frequency signals, the bandwidth of each one of the latter sets being substantially equal to the fixed bandwidth of the uplink frequency signals; and

, c. n sets of directional antenna means, each one thereof being responsive to a different one of the n sets of downlink frequency signals, for directing the downlink frequency signals in each set thereof toward a different geographical area.

8. An improved communication system as in claim 7 having additionally:

a. a plurality of amplifying means in the transponder, each one of such means being responsive to at least two differeNt downlink frequency signals from different ones of the n sets thereof, for amplifying the downlink frequency signals out of each one of the n frequency multiplying means; and

, b. multiplexing means to separate the amplified downlink frequency signals out of each one of the amplifying means and to direct each one of such separated and amplified downlink frequency signals to its corresponding directional antenna means.

9. An improved communication system as in claim 8 wherein the difference between each one of the different uplink frequency signals and its corresponding intermediate frequency signal is substantially equal to one-half the frequency of the corresponding downlink frequency signal and each one of the n frequency multiplying means doubles the frequency of the intermediate frequency signal applied thereto.