Telecommunications – Transmitter and receiver at same station – With frequency stabilization
Patent
1998-07-17
2000-06-06
Trost, William G.
Telecommunications
Transmitter and receiver at same station
With frequency stabilization
455260, 455264, 455265, 455130, 375376, 331 25, H03J 328, H03J 502, H03L 708, H04L 2722
Patent
active
060729929
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a high frequency apparatus for receiving digital modulated high frequency signals.
BACKGROUND ART
In the conventional high frequency apparatus, the inductance of tuning part of voltage controlled oscillator was formed with a strip type transmission line alone, for the sake of securing a high anti-vibration property.
Namely, if the inductance is formed with e.g. a coil component a vibration may cause vibration of wire of the coil, which invites a shift in the inductance value, resulting in a displacement of a tuned frequency. In order to avoid the occurrence of such phenomenon, the inductance was formed solely with a strip type transmission line.
A problem in the above described structure, where the inductance of tuning part is comprised of a strip type transmission line alone, is that fine tuning of tuning adjustment is not easy, because the dispersion due to component constant and mounting position of electronic components constituting local oscillator is compensated before completion.
DISCLOSURE OF THE INVENTION
The present invention is intended to present a high frequency apparatus having an inductance, with which the anti- vibration property is improved, the stability of oscillation frequency is assured for a long time, the tuning adjustment is easy, and a local oscillator supplies clearer output signal of less phase noise to a mixer.
For implementing the objective, an apparatus according to the present invention comprises an input terminal for receiving digital modulated high frequency signals, a mixer which receives the signals inputted to the input terminal at one input and an output signal of local oscillator at the other input, and an output terminal for delivering output signal of the mixer, said local oscillator being comprised of a voltage controlled oscillator, a frequency divider intervening in the control loop of the voltage controlled oscillator, a phase comparator and a loop filter. Said voltage controlled oscillator comprises an oscillation section and a tuning section. The tuning section comprises a frequency adjusting section and a means for maintaining a tuned state of the frequency adjusting section. Said control loop has a sufficiently high loop band width so as the noise of said local oscillator is not dominated by noise of said voltage controlled oscillator. Thus in an invented high frequency receiving apparatus the anti-vibration property is improved, the stability of oscillation frequency is ensured for a long term, the tuning adjustment is easy, and the local oscillator supplies clear output signals free from phase noise to the mixer.
An invented high frequency apparatus as recited in claim 1 comprises an input terminal for receiving digital modulated high frequency signals, a mixer for receiving the inputted signal at one input and output signal of local oscillator at the other input, and an output terminal for delivering output signal of the mixer; wherein, said local oscillator comprises a voltage controlled oscillator, a frequency divider intervening in the control loop of the voltage controlled oscillator, a phase comparator, and a loop filter. Said voltage controlled oscillator comprises an oscillation section and a tuning section. The tuning section comprises a frequency adjusting section and a means for maintaining a tuned state of the frequency adjusting section. Said control loop has a sufficiently high loop band width so as the noise of said local oscillator is not dominated by noise of said voltage controlled oscillator.
With the above described constitution, the tuning adjustment is easy because a frequency adjusting section has been provided as the tuning section of voltage controlled oscillator, furthermore the state of frequency adjusting section after adjustment is maintained by the maintaining means; the anti-vibration property etc, are therefore sufficiently assured.
Meanwhile, in a case when a maintaining means is used for assuring the anti-vibration property and the long term stability of oscillation fr
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patent: 4912437 (1990-03-01), Kuokkanen
patent: 5325401 (1994-06-01), Halik et al.
patent: 5335365 (1994-08-01), Ballantyne et al.
patent: 5390168 (1995-02-01), Vimpari
patent: 5423076 (1995-06-01), Westergren et al.
patent: 5461348 (1995-10-01), Heuberger et al.
Kitagawa Motoyoshi
Mishima Akira
Sumi Shigeharu
Davis Temica M.
Matsushita Electric - Industrial Co., Ltd.
Trost William G.
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