Wide bandwidth loop in a frequency shift keying (FSK) system

A transmitter for transmitting a modulated base band signal, said transmitter comprising:

• an output oscillator controlled by an error signal and providing an output signal;
• and
• a wide band width feedback loop, coupled to receive said output signal and said modulated base band signal, for providing said error signal in accordance with a phase or frequency difference derived from said output signal and said modulated base band signal;
• wherein said wide band width feedback loop comprises:
• a mixer reducing said output signal to a signal of a predetermined intermediate frequency;
• a discriminator, receiving said signal of a predetermined intermediate frequency, to provide a recovered base band signal;
• and
• a comparator for providing an error signal based on a signal difference between said recovered base band signal and said modulated base band signal.

A transmitter for transmitting a modulated base band signal, said transmitter comprising:

• an output oscillator controlled by an error signal and providing an output signal;
• and
• a wide band width feedback loop, coupled to receive said output signal and said modulated base band signal, for providing said error signal in accordance with a phase or frequency difference derived from said output signal and said modulated base band signal;
• wherein said wide band width feedback loop comprises:
• a mixer reducing said output signal to a first signal of a predetermined intermediate frequency;
• a modulator for modulating said modulated base band signal to a second signal of said predetermined intermediate frequency;
• and
• a phase detector detecting a phase difference between said first signal and said second signal and providing said error signal in accordance with said phase difference.

A method for transmitting a modulated base band signal, said method comprising the steps of:

• using an output oscillator to provide an output signal;
• providing a wide band width feedback loop, coupled to receive said output signal and said modulated base band signal, to providing an error signal to drive said output oscillator in accordance with a phase or frequency difference derived from said output signal and said modulated base band signal;
• and
• providing a narrow band width loop, said narrow band width loop receiving said output signal and a reference signal of a predetermined reference frequency to provide a DC correction signal to correct for a systematic drift in said output oscillator in accordance with a frequency or phase difference between said output signal and said reference signal.

A method for transmitting a modulated base band signal, said method comprising the steps of:

• using an output oscillator to provide an output signal;
• and
• providing a wide band width feedback loop, coupled to receive said output signal and said modulated base band signal, to providing an error signal to drive said output oscillator in accordance with a phase or frequency difference derived from said output signal and said modulated base band signal;
• wherein step of providing a wide band width feedback loop comprises the steps of:
• reducing said output signal to a signal of a predetermined intermediate frequency;
• receiving said signal of a predetermined intermediate frequency in a discriminator to provide a recovered base band signal;
• and
• providing an error signal based on a signal difference between said recovered base band signal and said modulated base band signal.

A method for transmitting a modulated base band signal, said method comprising the steps of:

• using an output oscillator to provide an output signal;
• and
• providing a wide band width feedback loop, coupled to receive said output signal and said modulated base band signal, to providing an error signal to drive said output oscillator in accordance with a phase or frequency difference derived from said output signal and said modulated base band signal;
• wherein said step of providing a wide band width feedback loop comprises:
• mixing said output signal with a reference signal to obtain a first signal of a predetermined intermediate frequency;
• modulating said modulated base band signal to obtain a second signal of said predetermined intermediate frequency;
• and
• detecting a phase difference between said first signal and said second signal and providing said error signal in accordance with said phase difference.