Automatic repeater station for signal transmissions

• US 5,408,681 A
• Filed: 08/16/1993
• Issued: 04/18/1995
• Est. Priority Date: 08/16/1993
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Levy, Yoram, Ressler, Elliott L., Bancroft, Douglas A.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Le, Thanh C.
• Application Number:
  US08/106,746
• Time in Patent Office: 610 Days
• Field of Search: 455/17, 455/20, 455/22, 455/23, 455/24, 455/126, 455/127, 330/149, 332/162, 332/160
• US Class Current: 455/17
• CPC Class Codes: H04B 7/15542 Selecting at relay station its transmit and receive resources selection of wireless resources by user or terminal H04W72/02; arrangements affording multiple use of the transmission path by two-dimensional division of the resources H04L5/0003, or by allocating sub-channels H04L5/003

Abstract

An automatic repeater station, sometimes called a relay system, is disclo. The relay system receives signals, preferably at one band of frequencies, then filters and restores their inherent information, and finally transmits the restored information, preferably at another band of frequencies. Unlike the prior art systems utilizing transceivers and electronically tunable filters, the present invention uses separate receivers and transmitters and is devoid of electronically tunable filters.

Claims

1. An automatic repeater station having a plurality of channels assigned thereto and that receives signals at a first range (F1) of frequencies and simultaneously transmits signals at a second range (F2) of frequencies, said signals of said first (F1) and second (F2) ranges of frequencies including a carrier having riding thereon amplitude modulated (AM) and/or frequency modulated (FM) information, said automatic repeater station having at least one receiving antenna and at least one transmitting antenna, said automatic repeater station comprising:

(a) a receiver splitter having its input stage coupled to said receiving antenna and its output stage connected to and supplying each of said plurality of channels with signals received by said receiving antenna;

(b) a first frequency synthesizer providing signals in a range of frequencies that includes and is higher than said first (F1) range of frequencies by a predetermined amount, said first frequency synthesizer having an output stage;

(c) a second frequency synthesizer providing signals in a range of frequencies that includes and is higher than said second (F2) range of frequencies by a predetermined amount, said second frequency synthesizer having an output stage;

(d) a frequency oscillator generating a signal at a frequency which is higher than an intermediate frequency by a predetermined amount, said frequency oscillator having an output stage;

(e) at least one down converter connecting one channel of said repeater to the output stage of said receiver splitter, said at least one down converter being connected to the output stages of and responsive to said first frequency synthesizer and said frequency oscillator, said at least one down converter shifting said received signals of said receiving antenna downward to the frequency of said intermediate frequency, said at least one down converter filtering and amplifying said received signals as the received signals are being shifted downward in frequency;

(f) means for receiving said downwardly frequency shifted signals and detecting and removing the amplitude modulated information from said downwardly frequency shifted signals, said means for detecting and removing also developing a first output containing the removed amplitude modulated information and also a second output, said second output serving as said intermediate frequency signal and which is devoid of amplitude modulated information;

(g) at least one up converter connected to receive said intermediate frequency signal, said at least one up converter being connected to the output stage of and responsive to said second frequency synthesizer and said frequency oscillator, said at least one up converter shifting the frequency of said intermediate frequency signal upward to said second (F2) range of frequency signals and amplifying and filtering said intermediate frequency signal while it is being shifted upward in frequency;

(h) a first operational amplifier for receiving said first output of said means for detecting and removing amplitude modulation;

(i) at least one power amplifier having a first input for receiving the output of said up converter and a second input, said power amplifier developing an output signal;

(j) at least one distortion reducer employing negative feedback and receiving the output signal of said power amplifier, said distortion reducer having means for rectifying said output signal of said power amplifier to an envelope signal, said envelope signal being applied to a second operational amplifier which, in turn, develops an output signal that is applied to a second input of said first operational amplifier, said first and second inputs of said first operational amplifier being arranged to be 180 degrees out-of-phase with respect to each other, said first operational amplifier having its output connected to said second input of said power amplifier;

(k) at least one quadraplexer having an input stage connected to the output signal of said power amplifier and an output stage connected to said transmitting antenna, said quadraplexer having a plurality of filters each with predetermined stopbands and passbands both being selected to respectively correspond to the frequency F2 and providing isolation between each of the plurality of channels using said transmitting antenna.

2. An automatic repeater station according to claim 1 further comprising an amplifier interposed between said first output of said means for detecting and removing the amplitude modulation and said at least one up converter.

3. An automatic repeater station having a plurality of channels assigned thereto and that receives signals at a first range (F1) of frequencies and simultaneously transmits signals at a second range (F2) of frequencies, said signals of first (F1) and second (F2) ranges including a carrier having riding thereon amplitude modulated (AM) and/or frequency modulated (FM) information, said automatic repeater station having at least one receiving antenna and at least one transmitting antenna, said automatic repeater station comprising:

(a) a receiver splitter having its input stage coupled to said receiving antenna and its output stage connected to and supplying each of said plurality of channels with signals received by said receiving antenna;

(b) a first frequency synthesizer providing signals in the range of frequencies that includes and is higher than said first (F1) range of frequencies by a predetermined amount, said first frequency synthesizer having an output stage;

(c) a plurality of down converters having a number corresponding to said plurality of assigned channels, each of said down converters comprising;

(i) at least one narrow band filter connected to the output stage of said receiver splitter, said at least one narrow band filter having a first bandpass section to pass said first range (F1) of frequencies, said narrow band filter further comprising switch means at its input stage and switch means at its output stage, each of said switch means being responsive to an applied control signal for routing the received signal from said receiver splitter to said first bandpass filter section, said at least one narrow band filter developing an output signal that is filtered by said first bandpass filter section;

(ii) a first mixer having a first input connected to the output stage of said first frequency synthesizer and a second input connected to the output of said at least one narrow band filter, said first mixer developing a first intermediate frequency signal equal to the difference between its input signals;

(iii) a frequency oscillator generating an output signal at a frequency which is higher than said first intermediate frequency by a predetermined amount;

(iv) a second mixer having a first input connected to said first intermediate frequency and a second input connected to the output signal of said frequency oscillator, said second mixer developing a second intermediate frequency signal equal to the difference between its inputs;

(d) means for detecting and removing the amplitude modulated information from said second intermediate frequency signal, said means for detecting and removing also developing a first output signal containing the removed amplitude modulated information and also a second output signal devoid of said amplitude modulated information;

(e) a first operational amplifier for receiving said first output signal of said means for detecting and removing and developing an output signal;

(f) a third mixer having a first input connected to said second output of said means for detecting and removing amplitude modulated information and a second input connected to the output signal of said frequency oscillator, said third mixer developing a third intermediate frequency signal equal to the difference between its inputs;

(g) a second frequency synthesizer providing signals in a range of frequencies that includes and is higher than said second (F2) range of frequencies by a predetermined amount, said second frequency synthesizer having an output stage;

(i) a fourth mixer having a first input connected to receive the third intermediate frequency signal of said third mixer and a second input connected to the output of said second frequency synthesizer, said fourth mixer developing a fourth intermediate frequency signal equal to the difference between its inputs;

(j) at least one second narrow band filter connected to receive the fourth intermediate frequency signals of said fourth mixer, said at least one second narrow band filter having a second bandpass filter section to pass said second range (F2) of frequency signals, said at least one second narrow band filter further comprising switch means at its input stage and switch means at its output stage, each of said switch means being responsive to applied control signals for routing the signals from the third mixer to said second bandpass section, said at least one second narrow band filter developing an output signal that is filtered by said second bandpass filter section;

(k) a power amplifier having a first input for receiving the output of said second at least one second narrow band filter and a second input, said power amplifier developing an output signal;

(l) a distortion reducer employing negative feedback and receiving said output signal of said power amplifier and having means for rectifying said power amplifier output signal to an envelope signal, said envelope signal being applied to a second operational amplifier which, in turn, develops an output signal that is applied to a second input of said first operational amplifier, said first and second inputs of said first operational amplifier being arranged to be 180 degrees out-of-phase with respect to each other, said first operational amplifier having its output connected to said second input of said power amplifier; and

(m) at least one quadraplexer having an input stage connected to the output signal of said power amplifier and an output stage connected to said transmitting antenna, said quadraplexer having a plurality of filters each having predetermined stopbands and passbands that are selected to correspond to one of the frequencies in said frequency band F2 and providing isolation between each of the plurality of channels sharing said transmitting antenna.

4. An automatic repeater station according to claim 3 further comprising a serially arranged amplifier and a third narrow band filter cooperating with said first narrow band filter to provide amplification and further filtering of the signal that is applied to said first mixer.

5. An automatic repeater station according to claim 3 further comprising a first serial arrangement of an amplifier, a second filter having a predetermined passband, and a third amplifier, said serial arrangement being interposed between said first and second mixers.

6. An automatic repeater station according to claim 3 further comprising a second serial arrangement of an amplifier and a filter having a predetermined passband, said second arrangement being interposed between said second mixer and said means for detecting and removing amplitude modulated information.

7. An automatic repeater station according to claim 3 further comprising an amplifier and conditioning module interposed between said second output of said means for detecting and removing amplitude modulated information and said third mixer.

8. An automatic repeater station according to claim 3 further comprising a third serial arrangement of an amplifier and filter having a predetermined passband, said third serial arrangement being interposed between said third and fourth mixers.

9. An automatic repeater station according to claim 3 further comprising a third serial arrangement of an amplifier, a third narrow band filter and another amplifier, said third arrangement interposed between said fourth mixer and said second narrow band filter.

10. An automatic repeater station according to claim 3, wherein said power amplifier comprises a three stage arrangement of field effect transistors with the first stage being biased for class A operation and the second and third stages being biased for class AB push-pull operation.