Diversity system

• US 4,142,155 A
• Filed: 05/11/1977
• Issued: 02/27/1979
• Est. Priority Date: 05/19/1976
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone East Corporation (Nippon Telegraph and Telephone Corporation)
• Inventors: Adachi, Fumiyuki
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/795,870
• Time in Patent Office: 657 Days
• Field of Search: 325/45, 325/47, 325/56, 325/59, 325/61, 325/145, 325/154, 325/156, 325/157, 325/158
• US Class Current: 375/260
• CPC Class Codes: H04L 1/04 using frequency diversity

Abstract

A common baseband digital signal is applied to a plurality of frequency modulators generating frequency modulated signals the carrier frequencies of which are equal to that of a common reference frequency oscillator, and the peak frequency deviations of the frequency modulated signals are made slightly different from each other.

Claims

1. A diversity system comprising

(a) a reference frequency oscillator,

(b) a plurality of frequency modulators each having means which generates frequency modulated signals the carrier frequencies of which are equal to each other and to that of said reference frequency oscillator,

(c) said plurality of frequency modulators generating frequency modulated signals with a common baseband digital signal being applied to said plurality of frequency modulators in such a manner that the peak frequency deviations of said modulated signals are different from each other, and

(d) the frequency modulated signals being transmitted from respective antennas connected to said plurality of frequency modulators, respectively.

2. A diversity system as set forth in claim 1 wherein each of said plurality of frequency modulators consists of an integrator and a phase modulator.

3. A diversity system as set forth in claim 1 wherein each of said plurality of frequency modulators consists of a combiner and a phase locked loop.

4. A diversity system as set forth in claim 3 wherein said phase locked loop consists of a voltage-controlled oscillator, a phase detector, and low pass filter.

5. A diversity system as set forth in claim 1, further comprising a receiver including a predetection filter having a bandwidth capable of receiving all of the modulated carriers transmitted from said transmitters.

6. A diversity system as set forth in claim 2, further comprising a receiver including a predetection filter having a bandwidth capable of receiving all of the modulated carriers transmitted from said transmitters.

7. A diversity system comprising:

(a) at least two angularly modulating transmitters;

(b) carriers in each transmitter being angularly modulated by a common baseband digital signal to different peak frequency deviations of said modulated carriers from each other; and

(c) said modulated carriers being transmitted from respective antennas connected to each transmitter.

8. A diversity system comprising:

(a) at least two angularly modulating transmitters;

(b) carriers of identical frequency in each transmitter being angularly modulated by a common baseband digital signal to different peak frequency deviations of said modulated carriers from each other; and

(c) said modulated carriers being transmitted from respective antennas connected to each transmitter.