Pulse or digital communications – Transmitters – Angle modulation
Reexamination Certificate
1998-07-06
2001-06-12
Chin, Stephen (Department: 2634)
Pulse or digital communications
Transmitters
Angle modulation
C455S115200, C455S121000, C455S123000, C455S193100
Reexamination Certificate
active
06246727
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a method and a system for tuning a resonance module in a radio base station. The resonance module having tuning means, a transmitter connection, and an antenna connection. High-frequency input and output signals on the transmitter and antenna connection, respectively, are sensed and processed to tune the resonance module to a frequency of the input signal on the transmitter connection. The processing of the sensed input and output signals includes processing in a low-frequency range.
Such an arrangement for tuning resonance modules is disclosed in the published PCT Application No. SE92/0004. That resonance module includes a resonant cavity and a resonance body, the position of which is adjustable by means of a motor to control the resonance frequency of the resonance module. As long as there is a phase difference between high-frequency input and output signals of the resonance module, the arrangement adjusts the position of the resonance body so as to reduce that phase difference. This prior art arrangement includes a voltage controlled oscillator that generates a high-frequency signal which is mixed with the input signal and the output signal in first and second mixers, respectively. Thus, two low-frequency signals are formed, the phase difference of which is a measure of a mistuning of the resonance module. Dependent thereon, the resonance module is tuned by means of the motor to a correct resonance frequency being the frequency of the input signal of the resonance module.
However, in this prior art arrangement, the voltage controlled oscillator is a relatively complicated and expensive component, which is required to have high dynamic performance since a relatively wide frequency range has to be scanned in the prior art tuning method.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a method for tuning a resonance module, which method reduces the time required for tuning the resonance module in response to variations in the frequency of an input signal of the resonance module. Further objects of the invention are to provide an efficient and accurate method wherein plural resonance modules can be tuned in a sequential process or in parallel processes, wherein multiplexing can be used to reduce required circuitry, wherein a VCO may be omitted, wherein a particularly efficient self-test and adjustment routine can be used in production as well as in operation, and/or wherein a low-frequency signal is efficiently generated, and to provide an efficient and cost-effective system for tuning a resonance module, in particular, for carrying out the method according to the invention.
These and other objects are attained by the method and the system according to the invention.
Advantages of embodiments of the inventive method and system are that different sensing may be performed in the same branch of the circuitry of the system leading to a reduction of possible measurement errors, that very fast “frequency hopping” may be performed if a fast tuning means is applied in the regulation system of the invention, that only the phase relation between the transmitter signal and the antenna signal remains in the low-frequency signal resulting in independence of the presently employed modulation width. It is possible in the inventive method and system to lower requirements on some major components to be connected to the resonance modules while still improving the tuning performance.
In particular, the inventive method may comprise the steps of: mixing an input signal, which is originating from a transmitter signal present on the transmitter connection, with a low-frequency signal so as to generate a single side band signal; mixing with the single side band signal an output signal being offset in phase from the input signal by a relative first phase difference dependent on a present tuning of the resonance module. The output signal being one in a group consisting of: a split portion of an antenna signal present on the antenna connection and a signal probed within the resonance module; mixing with the single side band signal a split portion of the transmitter signal on the transmitter connection; comparing, at a frequency range about the frequency of the low-frequency signal, mixing products resulting from the mixing of the single side band signal with the input and output signals, respectively, so as to determine a relative second phase difference between the input and output signals; operating, based on said second phase difference, the tuning means to tune the resonance module in order to adjust the second phase difference to a predetermined value or to be within a predetermined value range, so as to tune the resonance module to a present frequency of the input signal. It is pointed out that, depending on for instance technical requirements, other quantities than signal phase may be used in the inventive method.
The inventive method and system are applicable to any type of resonance modules including, but not limited to, cavity resonators, half-wave or quarter-wave resonators, and wave-guide resonators.
Further advantageous developments of the invention are set forth in the detailed description and other objects as follows:
It is an object of the invention that the second frequency is lower than the first frequency.
It is an object of the invention that the signal characteristics is at least one selected from a group consisting of: signal phase and signal amplitude.
A further object of the invention is mixing the input signal with the low-frequency signal in a quadrature modulator to generate the single-side-band signal, which is offset in frequency by a frequency difference between the mixing signal and the input signal.
Another object of the invention is low-pass filtering the mixing product resulting from the mixings of the single side band signal with the input and the output signals, respectively, so as to block frequencies above a frequency range about the mixing signal.
It is an object of the invention that the multiplexing and processing further input and output signals of further resonance modules are using common measurement circuitry and a common signal processing unit.
Another object of the invention is that the parallel processing further input and output signals of further resonance modules are using separate measurement circuitry and a common signal processing unit.
A further object of the invention is that multiplexing signals are to be mixed with the single-side-band signal.
REFERENCES:
patent: 3271684 (1966-09-01), Simon
patent: 4551682 (1985-11-01), Charpentier et al.
patent: 6041083 (2000-03-01), Larsson et al.
patent: WO90/06627 (1990-06-01), None
patent: WO92/12577 (1992-07-01), None
Folkesson Rolf
Johansson Bjorn
Larsson Lennart
Allgon AB
Chin Stephen
Ghayour Mohammad
Jacobson Price Holman & Stern PLLC
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