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

Abstract

A frequency modulated ratio 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 modulated exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exciter 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.

What is claimed is: 
     
       1. A synchronous frequency modulated booster 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 .Iadd.modulated by a frequency reference signal.Iaddend.; 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) means responsive to said receiving means for producing a frequency reference signal representative of the frequency modulated intermediate frequency signal,   (b) a first phase locked loop circuit responsive to said receiving means for producing a first stable phase locked frequency signal representative of the frequency modulated intermediate frequency signal,   (c) a second phase locked loop circuit including a first voltage controlled oscillator, said first voltage controlled oscillator generating the frequency modulated broadcast signal, said first voltage controlled oscillator being phase locked to said frequency reference signal produced by said means, and   (d) correcting phase locked loop circuit means responsive to the output of said first voltage controlled oscillator and responsive to said stable phase locked frequency produced by said first phase locked loop circuit and connected to said second phase locked loop circuit for correcting phase differences between the output of said first voltage controlled oscillator and said frequency reference signal produced by said means.     
     
     
       2. A synchronous frequency modulated booster 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 .Iadd.modulated by a frequency reference signal.Iaddend.; 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) means responsive to said receiving means for producing a frequency reference signal representative of the frequency modulated intermediate frequency signal,   (b) a first phase locked loop circuit responsive to said receiving means for producing a first stable phase locked frequency signal representative of the frequency modulated intermediate frequency signal,   (c) a second phase locked loop circuit including a first voltage controlled oscillator, said first voltage controlled oscillator generating the frequency modulated broadcast signal, said first voltage controlled oscillator being phase locked to said frequency reference signal produced by said means, and   (d) correcting phase locked loop circuit means responsive to the output of said first voltage controlled oscillator and responsive to said stable phase locked frequency produced by said first phase locked loop circuit and connected to said second phase locked loop circuit for correcting phase differences between the output of said first voltage controlled oscillator and said frequency reference signal produced by said means,   (e) said second phase locked loop circuit including a first mixer circuit, one input of said first mixer circuit being connected to the output of said first voltage controlled oscillator, said correcting phase locked loop circuit means including a second voltage controlled oscillator, said second voltage controlled oscillator being connected to another input of said first mixer circuit producing a signal for correcting phase differences between the output of said first voltage controlled oscillator and said frequency reference signal produced by said means.     
     
     
       3. A synchronous frequency modulated booster as claimed in claim 2 wherein said correcting phase locked loop circuit means includes a third phase locked loop circuit, said third phase locked loop circuit includes said second voltage controlled oscillator and a first voltage controlled crystal oscillator, said first voltage controlled crystal oscillator producing a second stable frequency reference signal for phase locking said second voltage controlled oscillator, said first phase locked loop circuit includes a second voltage controlled crystal oscillator for producing said first stable phase locked frequency signal, said first voltage controlled crystal oscillator being phase locked to the first stable frequency reference signal produced by said second voltage controlled crystal oscillator. 
     
     
       4. A synchronous frequency modulated booster as claimed in claim 3 wherein said third phase locked loop circuit includes a programmable frequency divider circuit to provide a rapid synthesized reference signal in the output of said second voltage controlled oscillator for correcting phase differences between the output of said second voltage controlled oscillator and said phase locked frequency reference signal produced by said first voltage controlled crystal oscillator. 
     
     
       5. A synchronous frequency modulated booster as claimed in claim 4 wherein said second phase locked loop circuit includes a second mixer circuit and wherein said correcting phase locked loop circuit means includes a fourth phase locked to loop circuit, the output of said first mixer circuit being connected to one input of said second mixer, said fourth phase locked loop circuit includes a third voltage controlled oscillator, said third voltage controlled oscillator being connected to another input of said second mixer circuit, said second mixer circuit in response to the output frequency signal of said first mixer circuit and in response to the output frequency of said third voltage controlled oscillator producing a frequency signal to correct phase differences between the output of said first voltage controlled oscillator and said frequency reference signal produced by said means. 
     
     
       6. A synchronous frequency modulated booster as claimed in claim 5 wherein said third voltage controlled oscillator is phase locked in said first stable phase locked frequency signal produced by said second voltage controlled crystal oscillator. 
     
     
       7. A synchronous frequency modulated booster as claimed in claim 5 wherein said fourth phase locked circuit includes a programmable frequency divider circuit to provide a rapid synthesized reference signal in the output of said third voltage controlled oscillator for correcting phase differences between the output of said third voltage controlled oscillator and said phase locked frequency reference signal produced by said first phase locked loop circuit. 
     
     
       8. A synchronous frequency modulated booster 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 .Iadd.modulated by a frequency reference signal.Iaddend.; 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) first means responsive to said receiving means for producing a frequency reference signal representative of the frequency modulated intermediate frequency signal,   (b) a phase locked loop circuit including a voltage controlled oscillator, said voltage controlled oscillator generating the frequency modulated broadcast signal, said voltage controlled oscillator being phase locked to said frequency reference signal produced by said first means, and   (c) second means including a phase error correcting circuit connected to the output of said voltage controlled oscillator and said phase locked loop circuit and responsive to said receiving means for correcting phase differences between the output of said voltage controlled oscillator and said frequency reference signal produced by said first means.     
     
     
       9. A synchronous frequency modulated booster as claimed in claim 8 wherein said first means includes a doubler circuit responsive to said receiving means for producing said reference signal representative of the frequency modulated intermediate frequency signal. 
     
     
       10. A synchronous frequency modulated booster as claimed in claim 8 wherein said phase error correcting circuit produces a first stable phase locking frequency signal for correcting phase differences between the output of the voltage controlled oscillator and said frequency reference signal produced by said first means, and said second means produces a second stable phase locking frequency signal for phase locking said first stable phase locking frequency signal. 
     
     
       11. A synchronous frequency modulated booster as claimed in claim 10 wherein said second means includes a phase locked loop circuit for producing said second stable phase locking frequency signal, said last-mentioned phase locked loop circuit being responsive to said receiving means for producing a phase locked frequency reference signal representative of the frequency modulated intermediate frequency signal. 
     
     
       12. A synchronous frequency modulated booster as claimed in claim 8 wherein said phase error correcting circuit includes a programmable frequency divider circuit to provide a rapid synthesized reference signal for correcting phase differences between the output of the voltage controlled oscillator and the reference signal produced by said first means.