Frequency modulated radio frequency broadcast network employing a synchronous frequency modulated booster system

• US 5,046,124 A
• Filed: 03/21/1989
• Issued: 09/03/1991
• Est. Priority Date: 03/21/1989
• Status: Expired

• Current Assignee: TFT Incorporated Santa Clara CA
• Original Assignee: TFT, Inc.
• Inventors: Hu, Charlie L., Law, Yee S., Wu, Joseph C.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Pham, Chi H.
• Application Number:
  US07/326,744
• Time in Patent Office: 896 Days
• Field of Search: 455/13, 455/14, 455/16, 455/20, 455/22, 455/23, 455/43, 455/51, 455/71, 455/75, 455/113, 455/118, 455/119, 455/208, 455/56, 455/259, 455/260, 455/265, 331/18, 331/25, 331/55
• US Class Current: 455/20
• CPC Class Codes: H03L 7/23 with pulse counters or frequency dividers
• CPC Class Codes: H04H 20/67 Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency

Abstract

A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modualted exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exicter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Claims

1. A synchronous frequency modulated booster system for re-transmitting a frequency modulated broadcast signal comprising:

A. transmitting means for re-transmitting a frequency modulated broadcast signal;

receiving means for receiving a frequency modulated intermediate frequency signal; and

C. a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means and applying to said transmitting means a frequency modulated broadcast signal for re-transmission by said transmitter means,

D. said synchronous frequency modulated exciter comprising;

(a) a first phase locked loop circuit for phase locking said frequency modulated intermediate frequency signal with a first stable reference signal, said first phase locked loop circuit comprising a stable frequency source from which said first stable reference signal is derived, and

(b) a second phase locked loop circuit for phase locking said frequency modulated broadcast signal with a second stable reference signal derived from said stable frequency source to synchronize said frequency modulated broadcast signal with said second stable reference signal thereby synchronizing said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal.

2. A synchronous frequency modulated booster system as claimed in claim 1 said synchronous frequency modulated exciter further comprising:

(a) a mixer circuit for said second phase locked loop circuit having a plurality of inputs and an output, said frequency modulated intermediate frequency signal being applied to one input of said mixer circuit, and

(b) a voltage controlled oscillator for said second phase locked loop circuit generating a signal for application to another input of said mixer circuit, said mixer circuit combining the signals applied to the inputs thereof for producing in the output thereof the frequency modulated broadcast signal,

(c) said second phase locked loop circuit producing a phase error correction signal for application to said voltage controlled oscillator for said second phase locked loop circuit in response to phase difference between said second stable reference signal and a comparison signal derived from said frequency modulated broadcast signal for phase locking said frequency modulated broadcast signal with said second stable reference signal to stabilize the frequency modulated broadcast signal applied to said transmitting means with said frequency modulated intermediate frequency signal bent by said receiving means.

3. A synchronous frequency modulated booster system as claimed in claim 2 wherein said frequency modulated intermediate frequency signal includes an intermediate frequency reference signal and wherein said stable frequency source is a voltage controlled oscillator and wherein said synchronous frequency modulated exciter further comprising:

(a) a phase detector for said first phase locked loop circuit having a plurality of inputs and an output,

(b) a discriminator circuit receiving said frequency modulated intermediate frequency signal from said receiving means for applying said intermediate frequency reference signal to one input of said phase detector for said first phase locked loop circuit,

(c) means including said voltage controlled oscillator for said first phase locked loop circuit for applying said first stable reference signal to said phase detector for said first phase locked loop circuit, and

(d) means connected to said output of said phase detector for said first phase locked loop circuit for applying from the output of said phase detector of said first phase locked loop circuit a phae error correction signal to said voltage controlled oscillator for said first phase locked loop circuit for phase locking said first stable reference signal applied by said means including said voltage controlled oscillator for said first phase locked loop circuit with said intermediate frequency reference signal to synchronize transmitting frequencies and modulated depth of said frequency modulated broadcast signal with said frequency modulated intermediate frequency sent by said receiving means.

4. A synchronous frequency modulated booster system as claimed in claim 3 wherein said synchronous frequency modulated exciter further comprising:

(a) a phase detector for said second phase locked loop circuit having a plurality of inputs and an output,

(b) means for said second phase locked loop circuit connecting said voltage controlled oscillator for said first phase locked loop circuit with one input of said phase detector for said second phase locked loop circuit for applying said second stable reference signal thereto,

(c) means for said second phase locked loop circuit applying a comparison signal derived from said frequency modulated broadcast signal to another input of said phase detector for said second phase locked loop circuit, and

(d) means for said second phase locked loop circuit connected to the output of said phase detector for said second phase locked loop circuit and said voltage controlled oscillator for said second phase locked loop circuit to apply said phase error correction signal of said second phase locked loop circuit to said voltage controlled oscillator for said second phase locked loop circuit for phase locking said frequency modulated broadcast signal with said second stable reference signal to stabilize said frequency modulated broadcast signal applied to said transmitting means with the frequency modulated intermediate frequency signal received by said receiving means.

5. A synchronous frequency modulated booster system as claimed in claim 3 wherein the reference signal included in said frequency modulated intermediate frequency signal is within composite baseband signals.

6. A frequency modulated broadcast network comprising:

A. a first broadcast station originating a frequency modulated broadcast signal, said first broadcast station comprising means for transmitting a frequency modulated intermediate frequency signal with a reference signal; and

B. a second broadcast station for re-transmitting said frequency modulated broadcast signal, said second broadcast station comprising a synchronous frequency modulated booster system for re-transmitting said frequency modulated broadcast signal, said synchronous frequency modulated booster system comprising;

(a) transmitting means for re-transmitting said frequency modulated broadcast signal,

(b) receiving means for receiving said frequency modulated intermediate frequency signal, and

(c) a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means and applying to said transmitting means a frequency modulated broadcast signal for re-transmission by said transmitting means,

(d) said synchronous frequency modulated exciter comprising;

1. a first phase locked loop circuit for phase locking said frequency modulated intermediate frequency with a first stable reference signal, said first phase locked loop circuit comprising a stable frequency source from which said first stable reference signal is derived, and

8. A frequency modulated broadcast network as claimed in claim 6 wherein said synchronous frequency modulated exciter further comprising:

1. a mixer circuit for said second phase locked loop circuit having a plurality of inputs and an output, said frequency modulated intermediate frequency signal being applied to one input of said mixer circuit,

2. a voltage controlled oscillator means for said second phase locked loop circuit generating a signal for application to another input of said mixer circuit, said mixer circuit combining the signals applied to the inputs thereof for producing in the output thereof the frequency modulated broadcast signal,

3. said second phase locked loop circuit producing a phase error correction signal for application to said voltage controlled oscillator for said second phae locked loop circuit in response to phase differences between said second stable reference signal and a comparison signal derived from said frequency modulated broadcast signal for phase locking said frequency modulated broadcast signal with said second stable reference signal to stabilize the frequency modulated broadcast signal applied to said transmitter means with said frequency modulated intermediate frequency signal sent by said receiving means.

10. A frequency modulated broadcast network as claimed in claim 8 wherein said synchronous frequency modulated exciter further comprising:

(a) a phase detector for said second phase locked loop circuit having a plurality of inputs and an output,

(b) means for said second phase locked loop circuit connecting said voltage controlled oscillator for said first phae locked loop circuit with one input of said phase detector for said second phase locked loop circuit for applying said second stable reference signal thereto,

(c) means for said second phae locked loop circuit applying a comprising signal derived from said frequency modulated broadcast signal to another input of said phase detector for said second phase locked loop circuit, and

(d) means for said second phase locked loop circuit connected to the output of said phae detector for said second phase locked loop circuit and said voltage controlled oscillator for said second phase locked loop circuit to apply said phase error correction signal of said second phase locked loop circuit to said voltage controlled oscillator for said second phase locked loop circuit for phase locking said frequency modulated broadcast signal with said second stable reference signal to stabilize said frequency modulated broadcast signal applied to said transmitting means with the frequency modulated intermediate frequency signal received by said receiving means.

11. A frequency modulated broadcast network as claimed in claim 6 wherein said means of said first broadcast station includes a receiver with an output providing a frequency modulated intermediate frequency signal, and an intermediate frequency transmitter for sending said frequency modulated intermediate frequency signal received from said receiver, said frequency modulated intermediate frequency signal sent by said intermediate frequency transmitter being received by said receiving means of said second broadcast station.

12. A frequency modulated broadcast network as claimed in claim 10 and comprising:

A. a third broadcast station for re-transmitting said frequency modulated broadcast signal, said third broadcast station comprising a synchronous frequency modulated booster system for re-transmitting said frequency modulated broadcast signal, said synchronous frequency modulated booster system for said third broadcast station comprising;

(a) transmitting means for re-transmitting said frequency modulated broadcast signal,

(b) receiving means for receiving said frequency modulated intermediate frequency signal from said receiver of said first broadcast station,

(c) a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means of said third broadcast station and applying to said transmitting means of said third broadcast station the frequency modulated broadcast signal for re-transmission by said transmitting means for said third broadcast station,

(d) said synchronous frequency modulated exciter for said third broadcast station comprising;

14. A frequency modulated broadcast network as claimed in claim 10 wherein said second broadcast station includes a synchronous frequency modulated transmitter for sending said frequency modulated intermediate frequency signal received from said receiver of said second broadcast signal received from said receiver of said second broadcast station and comprising;

A. a third broadcast station for re-transmitting said frequency modulated broadcast signal, said third broadcast station comprising a synchronous frequency modulated booster system for re-transmitting said frequency modulated broadcast signal, said synchronous frequency modulated booster system for said third broadcast station comprising;

(a) transmitting means for re-transmitting said frequency modulated broadcast signal,

(b) receiving means for receiving said frequency modulated signal from said intermediate frequency transmitter of said second broadcast station, and

(c) a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means of said third broadcast station and applying to said transmitting means of said third broadcast station the frequency modulated broadcast signal for re-transmission by said transmitting means of said third broadcast station,

(d) said synchronous frequency modulated exciter for said third broadcast station comprising;

16. A frequency modulated broadcast network as claimed in claim 6 wherein the reference signal included in the frequency modulated intermediate frequency signal of said first broadcast station is within composite baseband signals.

18. A synchronous frequency modulated booster system as claimed in claim 14 wherein the intermediate frequency signal received by said receiving means for application to said synchronous frequency modulated exciter includes a reference signal within composite baseband signals.

7. a second phase locked loop circuit for phase locking said frequency modulated broadcast signal with a second said stable reference signal derived from said stable frequency source to synchronize said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal.

9. A frequency modulated broadcast network as claimed in claim 7 wherein said stable frequency source is a voltage controlled oscillator and wherein said synchronous frequency modulated exciter further comprising:

1. a phase detector for said first phase locked loop circuit having a plurality of inputs and an output,

2, a discriminator circuit receiving said frequency modulated intermediate frequency signal from said receiving means for applying said intermediate frequency reference signal to one input of said phase detector of said first phase locked loop circuit,

3. means including said voltage controlled oscillator for said first phase locked loop circuit for applying said first stable reference signal to said phase detector for said first phase locked loop circuit, and

4. means connected to said output of said phase detector for said first phase locked loop circuit for applying from the output of said phase detector of said first phase locked loop circuit a phae error correction signal to said voltage controlled oscillator for said first phase locked loop circuit for phase locking said first stable reference signal applied by said means including said voltage controlled oscillator for said first phase locked loop circuit with said intermediate frequency reference signal to synchronize said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal sent by said receiving means.

13. a first phase locked loop circuit for phase locking said frequency modulated intermediate frequency signal with a first stable reference signal, said first phase locked loop circuit comprising a stable frequency source from which said first reference signal is derived anda second phase locked loop circuit for phase locking said frequency modulated broadcast signal with a second stable reference signal derived from said stable frequency source to synchronize said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal.

15. a first phase locked loop circuit for phase locking said frequency modulated intermediate frequency signal with a first stable reference signal, said first phase locked loop circuit comprising a stable reference source from which said first stable reference signal is derived, anda second phase locked loop circuit for phase locking said frequency modulated broadcast signal with a second stable reference signal derived from said stable frequency source to synchronize said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal.

19. A synchronous frequency modulated booster system for re-transmitting a frequency modulated broadcast signal as claimed in claim 15 and comprising a phase locked loop circuit interconnecting said receiving means and said transmitting means via said synchronous frequency modulated exciter for modifying the level of modulation of the frequency modulated intermediate frequency signal to an acceptable level of modulation.

17. A synchronous frequency modulated booster system for re-transmitting a frequency modulated broadcast signal comprising:

a. transmitting means for re-transmitting a frequency modulated broadcast signal;

b. receiving means for receiving a frequency modulated intermediate frequency signal; and

c. a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means and applying to said transmitting means a frequency modulated broadcast signal for re-transmission by said transmitter means, said synchronous frequency modulated exciter synchronizing said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal.

21. A frequency modulated broadcast network as claimed in claim 17 wherein said second broadcast station is serially fed from said first broadcast station.

22. A frequency modulated broadcast network as claimed in claim 17 wherein said second broadcast station is parallel fed from said first broadcast station.

23. A frequency modulated broadcast network as claimed in claim 17 wherein said second broadcast station is serially fed from said first broadcast station, said frequency modulated broadcast network comprising a third broadcast station parallel fed from said first broadcast station for re-transmitting said frequency modulated broadcast signal, said third broadcast station comprising a synchronous frequency modulated booster system for re-transmitting said frequency modulated broadcast signal, said synchronous frequency modulated booster system for said third broadcast station comprising:

(a) tramsmitting means for re-transmitting said frequency modulated broadcast signal,

(b) receiving means for receiving said frequency intermediate frequency signal, and

(c) a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means for said third broadcast station and applying to said transmitting means for said third broadcast station a frequency modulated broadcast signal for re-transmission by said transmitting means of said third broadcast station.

24. A frequency modulated broadcast network as claimed in claim 17 and comprising studio means for transmitting to said means of said first broadcast station said frequency modulated intermediate frequency signal and said reference signal.

25. A frequency modulated broadcast network as claimed in claim 17 and comprising studio means for transmitting to said means of said first broadcast station said frequency modulated intermediate frequency signal, said reference signal and a composite baseband signal of program signals.

26. A frequency modulated broadcast network as claimed in claim 17 and comprising studio means for transmitting to said means of said first broadcast station said frequency modulated intermediate frequency signal and said reference signal, said reference signal being an unmodulated signal.

27. A frequency modulated broadcast network as claimed in claim 17 wherein said first broadcast station includes a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said means of said first broadcast station for synchronizing said frequency modulated broadcast signal with said reference signal of said frequency modulated intermediate frequency signal.

28. A frequency modulated broadcast network as claimed in claim 17 wherein said synchronous frequency modulated exciter includes means for phase locking said frequency modulated broadcast signal of said second broadcast station to said reference signal.

29. A frequency modulated broadcast network as claimed in claim 21 wherein said studio means includes a frequency stable oscillator for generating said reference signal.

30. A frequency modulated broadcast network as claimed in claim 17 wherein said first broadcast station further comprising an intermediate frequency repeater transmitter connected to said means of said first broadcast station for transmitting to said receiving means of said second broadcast station said frequency modulated intermediate frequency signal and said reference signal.

31. A frequency modulated broadcast network as claimed in claim 27 and comprising studio means for transmitting to said means of said first broadcast station said frequency modulated intermediate frequency signal with said reference signal and program signals.

32. A frequency modulated broadcast network as claimed in claim 17 and comprising studio means having an intermediate frequency repeater transmitter for transmitting to said means of said first broadcast station and receiving means of said second broadcast station said frequency modulated intermediate frequency signal and said reference signal.

33. A frequency modulated broadcast network as claimed in claim 29 wherein said studio means transmits along with said frequency modulated intermediate frequency signal said reference signal and said program signals.

20. A frequency modulated broadcast network comprising:

A. a first broadcast station originating a frequency modulated broadcast signal, said first broadcast station comprising means for transmitting a frequency modulated intermediate frequency signal with a reference signal; and

B. a second broadcast station for re-transmitting said frequency modulated broadcast signal, said second broadcast station comprising a synchronous frequency modulated booster for re-transmitting said frequency modulated broadcast system signal, said synchronous frequency modulated booster system comprising;

(a) transmitting means for re-transmitting said frequency modulated broadcast signal,

(b) receiving means for receiving said frequency modulated intermediate frequency signal, and

(c) a synchronous frequency modulated exciter receiving said frequency modulated intermediate frequency signal from said receiving means and applying to said transmitting means a frequency modulated broadcast signal for re-transmission by said transmitting means, said synchronous frequency modulated exciter synchronizing said frequency modulated broadcast signal with said frequency modulated intermediate frequency signal.