Phase locked loop motor control circuit for tuning cavity resona

Details Phase locked loop motor control circuit for tuning cavity resona Phase locked loop motor control circuit for tuning cavity resona

1993-07-09

1994-12-20

Grimm, Siegfried H.

Oscillators

Automatic frequency stabilization using a phase or frequency...

Particular frequency control means

455123, 455125, H03L 706, H03J 716

Patent

active

053749057

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to an arrangement in tuning resonance modules including a cavity and resonance body, which is steered to a resonance position by a motor driven by a voltage as long as there is a phase difference between the input signal to the resonance module and its output signal, called the measuring signal, the input signal being of high frequency.
It is known in the art to provide a plurality of resonance modules working with a cavity and a resonance means movable in the cavity. In such modules there is thus used a reference signal originating from the input signal and a measurement signal which is the output signal from the cavity. The resonance means adjusts itself so that these two signals are brought to the same phase, thereby causing resonance in the module. When the input signal is high-frequency, also making the reference and measuring signals high-frequency, it is desirable to transpose the signals down to low frequency, with the intention of enabling the use of standard electronic units in comparing the signal phase positions. In addition, there is the problem that a plurality of signals of different frequencies and amplitudes can be received with mutual interference in a resonance module, and it is therefore important that signals from one or more adjacent modules shall be prevented from entering the specific module. Also, there is always a certain amount of reflection from the input signal to the resonance module, and this must not be allowed to return and interfere with the reference signal taken off from the signal.
The above-mentioned problems are solved in the present invention by its having been given the distinguishing features disclosed in the accompanying claims.
A preferred embodiment of the invention will now be described,
FIG. 1 is a circuit diagram in accordance with the invention.
FIG. 2 is a graph illustrating the frequency as a function of phase angle.
FIG. 3 is a graph illustrating the transposition of signal high frequency to low frequency for the same signal.
The letter A denotes a collection point on an antenna, where four signals of different frequencies are collected for common transmission from the antenna B. A signal 4' is sent from the resonance module 2. A transmitter is denoted by the letters PA, and a signal from it goes to an isolator 1 and further to the resonance module 2. The latter is formed with a cavity accommodating a movable resonance means driven by a motor until resonance occurs between the reference signal and the signal (called the measuring signal) coming from the module. Since the latter does not form any part of the invention it is not described further.
The isolator 1 solely permits passage of signals in the mentioned direction, and prevents any signal reflected in the module, as well as signals from the collection point A and through the module from reaching the transmitter PA. A reference signal is taken from the input at a point C. In the path of the reference signal there is an attenuator 3 for adjusting the signal to a level suitable to a mixer 4. The signal thus arrives at the mixer, and this reference signal from the attenuator is then mixed with an output signal from an oscillator 5. The mixer 4 gives one signal, which is the sum of the two input signals, and one which is the difference between the two signals. After the mixer there is a bandpass filter 6, which is formed for passing through the signal constituting the difference between the two input signals to the mixer 4. Consequently, if both the reference signal and the signal from the oscillator are of high frequency, but mutually close, the output signal from the mixer will be of low frequency and can pass through the bandpass filter 6. This can provide the lowest possible frequency, e.g. 20 to 220 kHz. These values should be viewed in relation to the frequency of the input signal from PA, which can be about 1000 MHz.
After the bandpass filter there is an attenuator 7, and this, together with an amplifier 8, determines a power range suitable for the system. There is th

REFERENCES:
patent: 3271684 (1966-09-01), Simon
patent: 4992745 (1991-02-01), Hirota et al.

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