Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Patent
1989-01-30
1991-02-26
Orsino, Joseph A.
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
455326, 455327, 363157, H04B 126
Patent
active
049967185
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a frequency converter circuit which is used in a satellite broadcast receiving apparatus or the like so as to convert the high frequency signals of 12 GHz or 4 GHz band to the intermediate frequency signals of 1 GHz band.
BACKGROUND ART
In the satellite broadcasting, there are instances where signals of two or more different polarizations (the linear and circular polarization with the linear polarizations being divided into vertical and horizontal polarizations and the circular polarizations being divided right-hand and left-hand circular polarizations) are sent from the same direction to a particular area. Therefore, it is desirable that in this area such signals of plurality of different polarizations can be received altogether.
In frequency converter circuits of receiving apparatus for receiving such satellite broadcast, those heretofore put in practice have been constructed as shown in FIG. 1. In other words, an OMT (Ortho-Mode Transducer) 3 is connected to an input waveguide portion 2 within a circuit proper 1. Connected to the OMT 3 are an A-system electric signal processing circuit 4 including a mixer circuit 11a and a B-system electric signal processing circuit 5 including a mixer circuit 11b. An A-system local oscillator 8a is connected to the mixer circuit 11a of the A-system electric processing circuit 4 and also a B-system local oscillator 8b is connected to the mixer circuit 11b of the V-system electric signal processing circuit 5. In this case, the oscillation frequencies of the A-system local oscillator 8a and the B-system local oscillator 8b are of the same frequency. Also, it is constructed so that the supply of power to the A-system electric signal processing circuit 4 and the A-system local oscillator 8a and the supply of power to the B-system electric signal processing circuit 5 and the B-system local oscillator 8b are provided externally of the converters respectively from an A-system output connector 6 and a B-system output connector 7 through their respective power supply circuits or an A-system power supply circuit 9a and a B-system power supply circuit 9b, respectively. As a result, in order to operate only one of the two systems, only one of the output connectors is supplied with power, whereas in order to operate the two systems simultaneously, the power is supplied through the output connectors of the two systems.
It is to be noted that in FIG. 1 numerals 10a and 10b designate high frequency (RF) amplifier circuits, and 12a and 12b intermediate frequency (IF) amplifier circuits.
Such conventional device is of the construction which incorporates the two converters in the circuit proper 1 and it must be said that it is irrational from the cost point of view to dispose within the same circuit proper as many as two local oscillators which operate at the oscillation frequency. Also, it is needless to say that although the two oscillators oscillate at the same frequency, it is difficult to make the oscillation frequencies exactly the same and the mutual interference and disturbance of the two kinds of oscillation outputs tend to present problems.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a frequency converter circuit capable of operating a plurality of systems of electric signal processing circuits each including a mixer circuit with a single local oscillator.
To accomplish the above object, the present invention is constructed so that a single local oscillator is provided within a converter, that a part of a power supply circuit is used in common such that the supply of power to the local oscillator is provided from an output connector of any of a plurality of systems, and that a biasing with a dc current is applied to a mixer diode of a mixer circuit in each of electric signal processing circuits to which the oscillation output signal of the local oscillator is supplied, and also a biasing power supply circuit is used in common such that the biasing is always applied during the operation of the
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patent: 3562651 (1971-02-01), Hoover et al.
patent: 4383334 (1983-05-01), Epsom
patent: 4406020 (1983-09-01), Reindel
patent: 4414686 (1983-11-01), Lenz
patent: 4492960 (1985-01-01), Hislop
patent: 4593411 (1986-06-01), Schiller
patent: 4648129 (1987-03-01), Hirai
patent: 4677692 (1987-06-01), Sakashita
13th International TV Symposium, 28th May-2nd Jun. 1983, Montreux, pp. 252-255, J. G. Chaplin et al., "European Satellite Broadcasting the Case for an FM Television Receiver".
Matsushita Electric - Industrial Co., Ltd.
Negash Kinfe-Michael
Orsino Joseph A.
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