Hitachi-Kokusai Electric Inc.

Kiyoshi Funada

Yoichi Okubo

Masaki Suto

Naoki Hongo

Toshio Takada

Masato Horaguchi

Kotaro Takenaga

Yasuo Sera

Shinichi Miyazaki

Tetsuhiko Miyatani

Takashi Uchida

Junya Dosaka

Kazuyoshi Sato

Junichiro Yamakawa

Noriyuki Kagaya

Hiroichi Yonenaga

Ahmet Üstün

A mobile studio and a method for using the mobile studio are disclosed. The mobile studio is provided with lower and upper frameworks. A lower framework includes a planar upper-tier frame and a planar lower-tier frame, the planar upper-tier frame has a connecting tab to secure the mobile studio to a vehicle. An upper framework is secured to the lower framework. The upper framework supports at least a production area. Preferably, the upper framework supports a storage area including a rack assembly. Preferably, the rack assembly faces a rear door, at least part of the rack assembly having a sound insulating material. The method for using the mobile studio is provided with securing a bracket onto the chassis of the vehicle, loading the mobile studio onto the bracket, and securing the mobile studio to the vehicle using the connecting tab.

Mobile studio and method for using mobile studio

The present invention relates to an economical and highly reliable receiving apparatus for receiving radio signals transmitted from a mobile communication terminal within radio zone. The receiving apparatus has antenna sections that receive radio signals transmitted from the mobile communication terminal and are provided in each of a plurality of sectors divided from the radio zone, and receiving units that are provided in each of the antenna sections and that perform a predetermined process to the radio signals received by the antenna section.

Receiving apparatus

A distortion compensator that compensates for distortion arising in a main amplifierthat amplifies a signal effectively compensates for third order distortion which is unbalanced between the higher frequency band and lower frequency band. An amplitude detectordetects the level of a signal subject to amplification and a signal level change direction detection meansdetects the direction of change in the level of the signal. A signal level change control meansstores the correspondence between the signal level and the mode of changing the signal in order to compensate for distortion for when the direction of change in the signal level is positive and when it is negative, and controls a signal change meansso that the amplitude and phase of the signal is changed in a mode of changing the signal corresponding to the detected direction of change in the signal level and the detected signal level. A signal change control content updating meansupdates the content of this correspondence so that the distortion contained in the signal after amplification is reduced.

Distortion compensator

A distortion reducing circuit compensates an upper side third-order distortion and a lower side third-order distortion produced by an amplifier for amplifying a fundamental signal including multiple frequency components. The distortion reducing circuit includes a second harmonic reflection coefficient regulation circuit, installed at an output side of the amplifier, for regulating reflection coefficients for multiple frequency components included in a second harmonic signal to have a constant value.

Distortion reducing circuit

There is provided a distortion canceling circuit for reducing an unbalance between a higher and a lower 3rd order distortion at frequencies of (2&middot;f &minus;f ) and (2&middot;f &minus;f ), respectively, the distortions being generated by an amplifier which amplifies an input signal having at least two frequency components, i.e., f and f . Phase modulation control means supply a control signal, which has a difference frequency of (f &minus;f ), to phase modulation means, the control signal being generated based on the amplified input signal outputted from the amplifier. The phase modulation means performs phase modulation on the amplified input signal based on the supplied control signal to thereby generate a higher and a lower side-band signal having frequencies of (2&middot;f &minus;f ) and (2&middot;f &minus;f ), respectively, each of which has an identical amplitude and a phase difference of 180&deg; with respect to each other. The distortion canceling circuit reduces the unbalance by using the side-band signals.

Distortion canceling circuit

A distortion compensation amplifier has a distortion detection loop that divides an input signal, amplifies one divided signal with an amplifier and uses the amplified signal and another divided signal to detect a distortion component generated and introduced into the amplified signal in the amplifier. The amplifier additionally has a distortion removal loop that removes the detected distortion component from the amplified signal produced by the amplifier. The distortion detection loop comprises a filter for reducing the distortion component of the amplified signal output by the amplifier that was generated and introduced into the amplified signal in the amplifier and detects the distortion component reduced by the filter. The distortion removal loop removes from the amplified signal the detected distortion component that was produced by the amplifier and reduced by the filter.

Distortion compensation amplifier

Excellent compensation of the distortion is realized with a distortion-compensated amplifier device that compensates a distortion that is generated in a main amplifier, through the respective operations of a circuit comprised of a distortion-detecting loop and a distortion-compensating loop and a pre-distortor. In a distortion-detecting loop, the signal is distributed. With respect to one distribution signal, a vector adjuster ( ) performs vector adjustment of it and the pre-distortor ( ) generates a distortion. A main amplifier ( ) amplifies this signal. The resulting amplification signal and the other distribution are composed, whereby a distortion component is detected. In a distortion-compensating loop, that amplification signal and this distortion component are composed to thereby eliminate the distortion component from the amplification signal. In a control part, a distortion component level detecting means ( ) detects the levels of the distortion component that is detected. Vector adjusting/controlling means ( ) and ( ) controls the vector adjusting means ( ) to thereby make the average value of those levels small. On the other hand, pre-distortor controlling means ( ) and ( ) controls the pre-distortor ( ) to thereby make the peak values of those levels.

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Tokyo, Japan

Kiyoshi Funada