Samsung Electronics Co., Ltd.

Bo-Gyu Na

Young-Bae Ji

A TDD digital radio communication system includes a local oscillator for generating a local oscillation frequency being N times the transmission intermediate frequency and a frequency divider for dividing the local oscillation frequency by N. The frequency divider is enabled in the transmission mode to generate the transmission intermediate frequency and is disabled in the reception mode to completely stop generating the transmission intermediate frequency, so as to prevent interference with the reception intermediate frequency.

TDD digital radio communication system and method for operating the same

A radio receiver, and a method therefore, for efficiently suppressing attenuation properties of a low frequency signal, in an analog frequency modulation type radio communication system. The radio receiver includes a first down-converter for mixing a modulated, high-frequency signal received by the radio receiver and a predetermined local oscillating signal to generate an intermediate frequency signal. A modulator modulates the predetermined local oscillating signal by an aural signal transmitted from the transmitter and generates a mixing signal for down-mixing the electrical signal representative of modulated, high-frequency signal. The mixed signal is then applied to the first down-converter. A second down-converter down-converts, in frequency, the intermediate frequency signal generated from the first down-converter into a baseband signal to generate the down-converted signal. A demodulator demodulates the down-converted baseband signal to a demodulated signal representative of the modulated, high-frequency signal received by the radio receiver.

Radio receiver and method for suppressing attenuation properties of a

A radio signal processing apparatus of a portable telephone which can share a first transmit/receive mode such as a digital/analog (D/A) compatible mode and second transmit/receive mode such as a personal communication service (PCS) mode. The radio signal processing apparatus includes: a frequency generator for generating frequencies necessary for a frequency conversion; a first mode converter for converting a frequency of a signal transmitted and received in the first mode according to a prescribed oscillating frequency generated from the frequency generator; a second mode converter for converting a frequency of a signal transmitted and received in the second mode according to a prescribed oscillating frequency generated from the frequency generator; an intermediate frequency processor for converting, transmitting and receiving intermediate frequencies according to a prescribed oscillating frequency generated from the frequency generator; a first switch for selectively connecting an antenna to the first mode converter or the second mode converter; and a second switch for selectively connecting the first mode converter or the second mode converter to the intermediate frequency processor.

Radio signal processing apparatus of portable telephone for sharing

An antenna configuration includes a rod antenna and a helical antenna that are independently operable. The helical antenna is composed of a helical coil installed within an antenna housing mounted on a main body of a communication device. A feeding connector is electrically coupled to a bottom portion of the helical coil to thereby connect the helical antenna to a circuit of the communication device. The rod antenna is composed of a rod functioning as a conductive metal core wire. The rod is surrounded by the helical coil and the feeding connector and is extendable from and retractable into the main body of the communication device. When the rod is retracted into the main body, the helical coil operates as the exclusive radiating element and operation of the rod antenna is disabled. When the rod is extended from the main body, the rod electrically short-circuits and disables operation of the helical coil, and thereby operates as the exclusive radiating element.

Radio antenna

A transmitting/receiving signal processing circuit incorporates a frequency discrimination demodulator and a frequency synthesis local oscillator having a heterodyne phase locked loop for high speed switching. The transmitting/receiving signal processing circuit is used in a digital cordless communication device and has a transmitter for converting a signal input through a speaker and transmitting the converted signal as a radio wave via an antenna. A receiver converts a signal received by the antenna and then transmits the converted signal to a user in a time division communication system using a single frequency channel for transmission and reception according to constant time periods. A frequency synthesizer is also provided and includes a first phase lock loop for synthesizing a reference frequency for channel conversion; a switching stage providing a local oscillation signal from the receiver as a heterodyning source in a receiving mode, and providing a signal multiplied by the reference frequency as the heterodyning source in a transmission mode; and a second phase locked loop connected between the first phase locked loop and the receiver, for receiving the heterodyning source and generating transmitting/receiving frequencies in the transmission/receiving modes, respectively.

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Kyungki-do, South Korea

Bo-Gyu Na