Method and apparatus for measuring the distance between a primary station and a secondary station
First Claim
1. In a method for measuring the distance between a primary station and a secondary station, each station having an antenna for the transmission and reception of continuous wave signals modulated by a measuring signal, the distance being determined at the primary station in the form of a magnitude proportional to the quotient of the phase difference between the phase of the transmitted measuring signal and the phase of the received measuring signal and the frequency of the measuring signal, the improvement which comprises the steps of:
- transmitting from the primary station a continuous wave signal which is modulated by a measuring signal which in turn can be frequency modulated by the frequency of the measuring signal;
additionally modulating at the secondary station this modulated continuous wave signal by a marker signal and reflecting such additionally modulated continuous wave signal in the form of a receiving signal to the primary station;
forming at the primary station a filtered mixed product from the signal reflected by the secondary station and a local oscillator signal of the primary station;
deriving from such filtered mixed product a useful signal freed of the frequency of the continuous wave signal and the frequency of the measuring signal;
amplitude demodulating the useful signal to thereby obtain an evaluation signal freed of the frequency of the marker signal;
said evaluation signal being dependent upon the phase difference between the measuring signals of the transmitted and received signals;
utilizing the evaluation signal in a regulation circuit for a change of the mean frequency of the measuring signal of the transmitted signal such that the mean phase difference between the measuring signals of the transmitted signal and the reflected signal assumes a predetermined value at a momentary steady-state condition of the regulation circuit.
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Abstract
A method and apparatus for measuring the distance between a primary station and a secondary station, each having an antenna for transmitting and receiving continuous wave signals, modulated by a measuring signal, the distance being determined at the primary station as a magnitude proportional to the quotient of the phase difference between the measuring signals of the transmitted and the received signals and the measuring signal frequency. The primary station transmits a continuous wave signal modulated by a measuring signal which in turn can be frequency modulated by the measuring signal frequency. At the secondary station this modulated continuous wave signal is additionally modulated by a marking signal and reflected to the primary station as the receiving signal. At the primary station there is obtained from the filtered mixed product from the signal reflected by the secondary station and a local oscillator signal of the primary station a useful signal which is freed of the continuous wave frequency and the measuring signal frequency. There is obtained from the useful signal by amplitude demodulation an evaluation signal freed from the marking signal frequency. The evaluation signal which is dependent upon the phase difference between the measuring signals of the transmitted and received signals is employed in a regulation circuit for a change of the mean measuring signal frequency of the measuring signal of the transmitted signal such that the mean phase difference between the measuring signals of the transmitted signals and the reflected signals assumes a predetermined value at its steady-state condition.
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Citations
17 Claims
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1. In a method for measuring the distance between a primary station and a secondary station, each station having an antenna for the transmission and reception of continuous wave signals modulated by a measuring signal, the distance being determined at the primary station in the form of a magnitude proportional to the quotient of the phase difference between the phase of the transmitted measuring signal and the phase of the received measuring signal and the frequency of the measuring signal, the improvement which comprises the steps of:
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transmitting from the primary station a continuous wave signal which is modulated by a measuring signal which in turn can be frequency modulated by the frequency of the measuring signal; additionally modulating at the secondary station this modulated continuous wave signal by a marker signal and reflecting such additionally modulated continuous wave signal in the form of a receiving signal to the primary station; forming at the primary station a filtered mixed product from the signal reflected by the secondary station and a local oscillator signal of the primary station; deriving from such filtered mixed product a useful signal freed of the frequency of the continuous wave signal and the frequency of the measuring signal; amplitude demodulating the useful signal to thereby obtain an evaluation signal freed of the frequency of the marker signal; said evaluation signal being dependent upon the phase difference between the measuring signals of the transmitted and received signals; utilizing the evaluation signal in a regulation circuit for a change of the mean frequency of the measuring signal of the transmitted signal such that the mean phase difference between the measuring signals of the transmitted signal and the reflected signal assumes a predetermined value at a momentary steady-state condition of the regulation circuit. - View Dependent Claims (2)
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3. A circuit for measuring the distance between a primary station and a secondary station, comprising:
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a respective antenna provided for each said primary station and secondary station; said primary station containing; a microwave coupling circuit; a primary modulator and a mixer connected with said microwave coupling circuit; a distance evaluation circuit; said mixer being connected with said distance evaluation circuit; said distance evaluation circuit including a measuring signal frequency generator having a first output side and a second output side; a measuring device; said measuring signal frequency generator being connected at its first output side with said primary modulator and at its second output side with said measuring device; said measuring frequency signal generator including a controlled oscillator which modulates and controls the frequency of the measuring signal so as to assume a mean value; said distance evaluation circuit further including a bandpass filter; said measuring signal frequency generator having an input side; said input side of said measuring signal frequency generator being connected by means of said bandpass filter with said mixer. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification