Communications: directive radio wave systems and devices (e.g. – With particular circuit – For pulse modulation
Reexamination Certificate
1999-04-14
2001-02-27
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
With particular circuit
For pulse modulation
C342S128000, C342S130000, C342S131000, C342S132000, C342S134000, C342S175000, C342S200000, C342S201000
Reexamination Certificate
active
06195036
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a pulse radio technique and, more concretely, to radar system designs and the one can be used in radar system of aviation, sea and river transport, other transport means, as well as for mapping earth surface, meteorological, ecological and other researchs of atmosphere, and other aims. It is the most perspective to use this invention in ground apparatus of small and middle sized aerodromes and navigation apparatus of aircrafts. These navigation apparatus can be designed for operating at fires, mountains, fog or low clouds.
It is known pulse radar systems created on the basis of frequency-agile magnetrons and using a tracking of a resonant frequency of magnetron oscillating system (“cold frequency” of magnetron) during a pause between pulses. For example, the radar system constructed on the basis of the magnetron YJ 1172 Philips Corporation (prospects “Pulsed Magnetron X-band YJ 1172” or “Frequency Agility Packages”) comprises said frequency-agile magnetron receiving a signal from a low power source (a local oscillator) tuned by a varactor scheme. During a pause between pulses, a tracking of magnetron frequency is fulfilled by laying a signal, frequency 4 MHz, on the tuning voltage of said low power source and measuring a phase of resulted signal coming from a tracking detector after its reflection by the magnetron.
A coarse tuning of a frequency of the local oscillator has been begun by a synchronizing pulse about 1 &mgr;s before the magnetron generates its pulse. A precise tuning of a frequency of that oscillator is being fulfilled in the process of generating the magnetron pulse.
That construction of the radar system permits to set a local oscillator at the frequency providing an intermediate frequency of a receiver rather precise, if the intermediate frequency of the receiver is nearby to the difference between “cold frequency” of the magnetron in the pause between pulses and the frequency of the signal, generated by the magnetron.
However, that construction does not provide operation of the radar system for predetermined frequencies of any pulse, especially for high destabilizing factors and changes of tuning frequency rate in the operation process. This conducts to a limitation of information from the radar system, a decrease of its frequency agility and a reduction of the reliability of the radar system.
Besides that, a necessity of fast tuning of frequency during a pause between pulses does not permit to use the most stable, fixed local oscillators. The system of tuning of frequency with an use of the additional source of the signal, frequency 4 MHz, and the measuring of a phase of the resulted signal after a tracking detector make the construction of the radar system much more complicated and its operation less reliable because of additional possible defects in the system of tracking and tuning.
An essential defect of that construction is also impossible to realize operation at one or a few frequencies fixed with high accuracy, if a vibration and other destabilizing factors influence changing a magnetron frequency.
This decreases the universality and the reliability of that radar system in addition.
SUMMARY OF THE INVENTION
An aim of this invention is to increase the quantity of information and the reliability of the radar system so as to receive the possibility of fast conversion (during one period of magnetron pulse repetition) from operation with the frequency turning from pulse to pulse to operation at one or a few fixed frequencies and back.
Said aim is provided by using a radar system comprising a magnetron, an input for giving a feeding voltage of a magnetron tunner, a modulator connected to the magnetron and forming pulses of a feeding voltage for the magnetron, a low power microwave signal source connected to the magnetron and giving its signal to the magnetron in pauses between pulses, and differing from the nearest known designs by that said low power microwave signal source has frequencies fixed during each period of magnetron pulse repetition and differing from frequencies of correspondent signals generated by the magnetron, and that the radar system comprises a signal converter which can receive said low power signals reflected by the magnetron and convert these signals into the signals connected in time to the moments, when the frequencies of said low power source and the oscillating system of the magnetron coincide with each other, and used for triggering the modulator connected to said signal converter.
Another embodiment of that pulse radar system designed in addition for a reception of the signal reflected from target also includes a receiver designed for processing these signals and an antenna connected to the receiver and receiving said signals.
Next embodiment of said radar system designed for both a radiation and a reception of the signal differs from previous by that the receiver is connected to said low power microwave signal source to transfer synchronizing signals to said source for switching its frequencies.
Further embodiment differs from two previous by that the receiver is connected in addition to said low power microwave signal source, which, in this case, is also a local oscillator of the receiver and gives its signals to the receiver.
It is also possible other present radar system embodiments, which allow to resolve a problem of increase of information and reliability of radar systems.
The offered shift of structure of radar system provides essential advantages of that system to the nearest known design, for example:
The radar system radiates the signal of the predetermined frequency, which may be an independent source of information.
The radiated frequency is conditioned only the frequency of the low power microwave signal source and may be shifted easily from pause to pause between pulses by an arbitrary, for example, random law or, in case of need, may be kept up constant.
The radiated frequency does not depend on destabilizing factors, shifts of a tuning rate, and a transition to a work at the fixed frequency and back. That increases the information and the reliability of the present radar system thanks to a use of the exact predetermined frequency as an additional source of the information and a considerable increase of the reliability of the radar system by means of fast transition from one regime of operation to another.
It is possible very simple way, for instance, by shifting a feeding voltage of the tuner of the magnetron, that is by shifting a rate of tuning, at the same time, to shift the disposition of pulses. That increases the quantity of the information and the reliability of the radar system in addition.
REFERENCES:
patent: 3996588 (1976-12-01), Besson et al.
patent: 4001825 (1977-01-01), Burgers
patent: 4071844 (1978-01-01), Hopwood et al.
patent: 4330760 (1982-05-01), Busacca et al.
patent: 4682178 (1987-07-01), Anflo et al.
patent: 1820346 A1 (1993-06-01), None
Data Sheet, Pulsed Magnetron X-band (YJ 1172), Philips, pp. 22 and 24, No Date.
Application Note, Frequency Agility Packages, Philips, pp. 118, 121-123, No Date.
Gregory Bernarr E.
Hardaway/Mann IP Group Nexsen Pruet Jacobs & Pollard, LLP
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