Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Takaaki Konishi

Kazuya Ueda

Hiroshi Azakami

Naoya Tokunaga

Hisaya Kato

Yoshikazu Hayashi

Hiroaki Ozeki

Teruaki Hasegawa

Noriaki Omoto

Takashi Hasegawa

Kazuaki Suzuki

Kunio Ninomiya

Toshiyuki Satomi

A first interpolation sectionand a second interpolation sectionperform sampling on input data Idand Qdhaving a sampling frequency fover so that resulting data will have a sampling frequency fsamp, which is equal to an operating clock frequency of a digital-to-analog converter, which is an output destination. In the above manner, the data is interpolated. At this time, the first interpolation sectionand the second interpolation sectionperform interpolation using a frequency ratio between the sampling frequency fover and the sampling frequency fsamp. Then, output data Idand Qdhaving the sampling frequency fsamp is outputted to a quadrature modulation section

Apparatus and method for digital modulation

A synchronization error occurs when a DTV signal is distorted on a transmission path and this deteriorates demodulation capability. The digital demodulation device and the synchronization detecting method of the invention can correct the synchronization position when determining that a synchronization error has occurred. A controller receives a center tap coefficient, for example, from a waveform equalizer and compares the coefficient with a given center tap coefficient threshold. If the coefficient is smaller than the threshold, the controller determines that a synchronization detector has made a synchronization error and outputs a control signal. The synchronization detector receiving the control signal re-detects a sync signal included in a received signal, to detect a new correct sync signal and thus correct the synchronization error.

Digital demodulation device and synchronization detecting method

In a digital broadcast receiving apparatus for amplifying a received modulated digital signal wave with automatically adjusted gain and demodulating the modulated signal wave to a digital signal, a tuner frequency-converts the modulated digital signal wave to generate a first modulated signal. A first automatic gain control amplification unit controls gain of the tuner to make a level of the first modulated signal at a first predetermined level. An A/D converter converts the first modulated signal into a second modulated signal. A demodulator demodulates the second modulated signal to generate a first demodulated digital signal. A second automatic gain control amplifier generates a second demodulated digital signal where frequency fluctuations included in the digital modulated wave are eliminated.

Digital broadcast receiving apparatus

A carrier recovery apparatus capable of detecting a phase error of modulation signal by a simple calculation, reducing the circuit scale, and improving the frequency capture characteristic and phase jitter characteristic is presented. This carrier recovery apparatus comprises a symbol estimating unit for estimating the transmitted symbol, a phase error detector for generating a normalized phase error signal on the basis of the estimated symbol and reception signal, a loop filter for filtering the phase error, and a numerical control oscillator controlled by the loop filter.

Carrier recovery apparatus

An input signal DT contains a segment synchronization signal compliant with the ATSC standard. A clock multiplication sectionmultiplies a clock CK. A switchable sampling sectionselects a sample point from among a plurality of timing points that are defined by the multiplied clock, and samples the input signal DT at the selected sample point. Moreover, the switchable sampling sectionswitches sample points from one to another in a synchronization-unestablished state. Once the segment synchronization is established, a synchronization detection device may maintain a synchronization-established state until the field synchronization detection fails, or the synchronization detection device may output a synchronization detection signal after shifting it in the time direction based on a bit error rate RT of the input signal.

Synchronization detection apparatus

A digital demodulation apparatus automatically controls gain based on a state of receiving a digital modulated signal. The digital demodulation apparatus amplifies a digital modulated signal wave received through the air with the gain automatically controlled so as to have a predetermined amplitude. In the digital demodulation apparatus, a receive level variation detector detects receive level variation, an amount of noise components of the received digital signal wave. A gain controllercontrols the gain with a receive level variation adaptive control signal based on the detected receive level variation, the amount of noise components.

Automatic gain control for digital demodulation apparatus

In an automatic gain control amplifier, an RF automatic gain controller controls the gain of a radio frequency signal. A frequency converter frequency-converts the radio frequency signal into an intermediate frequency signal. An IF automatic gain controller controls the gain of the intermediate frequency. A level detector detects a signal level of the gain-controlled intermediate frequency signal, and generates a level signal. An automatic gain control signal generator separately controls, based the level signal, the RF automatic gain controller and the IF automatic gain controller.

Automatic gain control apparatus

VSB receiver

A broadcast receiving apparatus provides multifunctionality to cope with analog modulated input signals as well as digital input signals modulated by various types of modulation schemes. The apparatus comprises a detector for detecting the modulation scheme of input signals, and a switch for switching one or more of the characteristic of a filtering section, an amplifying section, and a detection section, depending upon the detected modulated scheme.

Broadcast receiving apparatus

A digital broadcast receiver for receiving a digital modulation signal of the present invention includes channel selection means inputting a digital modulation signal of a radio frequency band and frequency converting a desired digital modulation signal into a designated intermediate frequency signal; oscillation means for generating a local oscillation signal used for frequency conversion at the channel selection means; oscillation frequency control means for controlling a frequency of the local oscillation signal at the oscillation means; phase noise characteristic control means for improving a phase noise characteristic of the local oscillation signal generated at the oscillation means; filter means for extracting the intermediate frequency signal selected at channel selection means; orthogonal detection means for orthogonally detecting the intermediate frequency signal extracted at the filter means; A/D converter means for converting the analog output of the orthogonal detection means into a digital signal; and digital demodulation means for digitally demodulating the output of the A/D converter means; and makes a high performance digital reception possible which can improve an AFC function by the channel selection means and can improve a bit error rate at the same time.

Digital broadcast receiver

A receiving apparatus is presented, in which a channel frequency can be selected over a wide band with an increased attenuation at an image frequency and/or at a local oscillation frequency by including a tunable filter having a following construction. Microstrip lines are connected between either one of the input or the output terminal or both of the input and output terminals of the tunable filter; a plurality of resonant circuits are formed by each of a plurality of coils and a plurality of variable capacitance diodes; and the coils are electromagnetically coupled and where a voltage applied to each cathode of each of a plurality of variable capacitance diodes through each of a plurality of resistors is controlled to tune a frequency to be received.

Growing community of inventors

Ibaraki, Japan

Takaaki Konishi