Phase-shift modulation of a direct antenna-driving VCO

A modulated oscillator having a radio-frequency output and a modulation input, the frequency or phase of the radio frequency output being controlled by a signal applied to the modulation input, comprising:

• a voltage controlled oscillator having a radio-frequency output and a control input, the frequency of the radio-frequency output being controlled by the voltage applied to the control input,
• a detector having first and second inputs and an error output, the error output comprising a voltage related to the frequency or phase difference between the signals present at the first and second inputs;
• a reference oscillator having a radio-frequency output coupled to the first input of the detector;
• the second input of the detector being coupled to the radio-frequency output of the voltage-controlled oscillator, the coupling of the radio-frequency output of the voltage controlled oscillator to the second input of the detector comprising a feedback path;
• the error output of the detector being coupled to the control input of the voltage controlled oscillator, the coupling of the error output of the detector to the control input of the voltage controlled oscillator comprising an error path;
• such that the error output of the detector is related to the phase or frequency difference between the signal present at the radio-frequency output of the voltage controlled oscillator and the radio-frequency output of the reference oscillator;
• the referne oscillator, voltage controlled oscillator, and detector, and the error path and feedback path comprising a phase-locked loop;
• the voltage on the error path and the radio-frequency signal on the feedback path comprising a feedback signal in the phase-locked loop, such that the radio frequency output of the modulated oscillator is controlled by the phase-locked loop through the feedback signal, and
• a keyed phase shift netowrk in the feedback path of the phase-locked loop between the radio-frequency output of the voltage-controlled oscillator and the second input of the detector, having at least one switching control input coupled to the modulation input such that a signal at a switching control input of the keyed phase shift network causes a phase shift of a predetermined amount;
• the keyed phase shift network being a differential phase shift keyer havng a plurality of switching control inputs, such that a plural;ity of phase shifts may be introduced by combinations of signals at the plurality of inputs, in which the keyed phase shift network comprises:
• a capacitor having a first end coupled to the second input of the detector and a second end connected to ground;
• a first resistor having a first end and a second end, the second end being coupled to the first end of the capacitor;
• a plurality of .DELTA.R networks connected in series, each having a signal path input and a signal path output and a switching control input, the signal path input of the first .DELTA.R network being coupled to the radio frequency output of the voltage-controlled oscillator, the output of the last .DELTA.R network being coupled to the first end of the first resistor of the phase shift keyer, the switching control input of each .DELTA.R network being coupled to one of the plurality of switching control inputs of the phase shift keyer, each .DELTA.R network comprising:
• a shift resistor having a first end coupled to the signal path input of the .DELTA.R network and a second end coupled to the signal path output of the .DELTA.R network;
• switching means means for making or breaking a connection in response to a signal present at the switching control input, having a first terminal coupled to the first end of the shift resistor and a second terminal coupled to the second end of the shift resistor, such that a signal on the switching control input causes the switching means to change conductive state, shunting the shift resistor;
• the values of the shift resistors of the .DELTA.R networks, the first resistor of the phase shift keyer and the capacitor being chosen such that introducing one or more signals at the switching control inputs of the plurality of .DELTA.R networks causes the switching means of the plurality of .DELTA.R networks to shunt their respective shift resistors, thus introducing a plurality of phase shifts of predetermined value.

A modulated oscillator having a radio-frequency output and a modulation input, the frequency or phase of the radio frequency output being controlled by a signal applied to the modulation input, comprising:

• a voltage controlled oscillator having a radio-frequency output and a control input, the frequency of the radio-frequency output being controlled by the voltage applied to the control input,
• a detector having first and second inputs and an error output, the error output comprising a voltage related to the frequency or phase difference between the signals present at the first and second inputs;
• a reference oscillator having a radio-frequency output coupled to the first input of the detector;
• the second input of the detector being coupled to the radio-frequency output of the voltage-controlled oscillator, the coupling of the radio-frequency output of the voltage controlled oscillator to the second input of the detector comprising a feedback path;
• the error output of the detector being coupled to the control input of the voltage controlled oscillator, the coupling of the error output of the detector to the control input of the voltage controlled oscillator comprising an error path;
• such that the error output of the detector is related to the phase or frequency difference between the signal present at the radio-frequency output of the voltage controlled oscillator and the radio-frequency output of the reference oscillator;
• the reference oscillator, voltage controlled oscillator, and detector, and the error path and feedback path comprising a phase-locked loop;
• the voltage on the error path and the radio-frequency signal on the feedback path comprising a feedback signal in the phase-locked loop, such that the radio frequency output of the modulated oscillator is controlled by the phaselocked loop through the feedback signal, and
• a phase shift keyer in the error path between the error output of the detector and the control input of the voltage controlled oscillator, having at least one switching control input coupled to the modulation input such that a signal at a switching control input of the phase-shift keyer injects a perturbation into the error path of the phase locked loop, causing a phase shift of a predetermined amount in the radio-frequency output of the voltage controlled oscillator.

A phase-shift modulator for radio-frequency oscillators of the kind comprising a voltage controlled oscillator having a radio-frequency output and a control input, the frequency of the radio-frequency oiutput being controlled by the voltage applied to the control input, a detector having first and second inputs and an error output, the error output comprising a voltage related to the frequency or phase difference between the signals present at the first and second inputs;

• a reference oscillator having a radio-frequency output coupled to the first input of the detector;
• the second input of the detector being coupled to the radio-frequency output of the voltage-controlled oscillator, the coupling of the radio-frequency outpt of the voltage controlled oscillator to the second input of the detector comprising a feedback path;
• the error outpuit of the detector being coupled to the control input of the voltage controlled oscillator, the coupling of the error output of the detector to the control input of the voltage controlled oscillator comprising an error path;
• such that the error output of the detector is related to the phase of frequency difference between the signal present at the radio-frequency output of the voltage controlled oscillator and the radio-frequency output of the reference oscillator;
• the reference oscillator, voltage controlled oscillator, and detector, and the error path and feedback path comprising aphase-locked loop;
• the voltage on the error path and the radio-frequency signal on the feedback path comprising a feedback signal in the phase-locked loop, such that the radio frequency output of the modulated oscillator is controlled by the phase-locked loop through the feedback signal;
• the modulator comrpising phase-shift network means for introducing the modulsting signal as a keyed perturbation of the error voltage in the error path in respnse to the modulating signal.

A modulated oscillator having a radio-frequency output and a modulation input, the frequency or phase of the radio frequency outptu being controlled by a signal appleied to the modulation inpout, comprising:

• a voltage controlled oscillator having a radio-frequency output and a control input, the frequency of the radio-frequency output being controlled by the voltage applied to the control input,
• a detector having first and secod inputs and an error output, the error output comprising a voltage related to the frequency or phase difference between the signals present at the first and second inputs;
• a referene oscillator having a radio-frequency output coupled to the firs input of the detector;
• the frequency of the radio frequency output of the reference oscillator being less than the frequency of the radio-frequency output of the voltage controlled oscillator,
• the second input of the detector being coupled to the radio-frequency output of the voltage-controlled oscillator, the coupling of the radio-frequency output of the voltage controlled oscillator to the second input of the detector comprising a feedback path;
• divider means for dividing the frequency of a signal, the divider means being in the feedback path betwen the radio-frequency output of the voltage controlled oscillator and the second input of the detecotr,
• the error output of the detector being coupled to the control input of the voltage controlled oscillator, the coupling of the error output of the detector to the control input of the voltage controlled oscillator comprising an error path;
• such that the error output of the detector is related to the phase or frequency difference betwen the signal present at the radio-frequency outptu of the voltage controlled oscillator and the radio-frequency output of the reference oscillator;
• the refrenc eoscillator, voltage controlled oscillator, and detector, and the error path and feedback path comrpissing a phse-locked loop;
• the voltage on the error path and the radio-frequency signal on the feedback path comprising a feedback signal in the phase-locked loop, such that the radio frequency output of the modulated oscillator is controlled by the phase-locked loop throgh the feedback signal,
• a keyed phase shift network in the feeeback path of the phase-locked loop between the radio-frequency outpout of the voltage-cpntrolled oscillator and the second input of the detector, having at least one switching control input coupled to the modulation input such that a signal at a switching control input of the keyed phase shift network causes a phase shift of a predetermined amount;
• the cumulative phase of the modulated radio-frequency output of the voltage controlled oscillator is resitrcited to a predetermined range of 2.pi. by adding to or subtracting from the count in the divider when the cumul;ative phase rolls over.