Abstract: An RFID system (10) has an interrogator (11), an interrogator antenna (12) connected to the interrogator (11), for transmitting a signal, a radio wave reflecting plate (21) reflecting the signal transmitted from the interrogator antenna (12) and including a part of a parabolic curve or a curve similar thereto, and a radio frequency tag (13) responding an receiving the signal from the interrogator antenna (12) via at least the radio wave reflecting plate (21) and communicating with the interrogator (11). A signal having passed without being applied to the radio frequency tag (13) is reflected toward the inside of the radio wave reflecting plate (21) by the radio wave reflecting plate (21). Therefore, the signal is prevented from scattering, so that the signal from the interrogator antenna (12) is effectively utilized.

Abstract: A transponder used in a remote identification system requiring an interrogator and a transponder. The transponder which is thin and compact includes a transmit/receive antenna which is thin for receiving an interrogating signal and a rewrite signal emitted from the interrogator, and for emitting a response signal towards the interrogator. There is a modulator/demodulator for modulating a signal according to a code inherent in the transponder to emit the same from the antenna as the response signal without newly applying energy to the interrogating signal, and for demodulating the rewrite signal. A controller for applying a modulating signal generated according to the inherent code to the modulator/demodulator and for storing a signal demodulated by the modulator/demodulator. A liquid crystal display is used for displaying data including bar codes which can be read by a bar code reader. The bar code can be rewritten.

Abstract: A GPS position measuring system includes at least one mobile station and a base station associated with the mobile station. The mobile station is provided with an antenna for receiving one or more GPS signals from the corresponding GPS satellites, an amplifying and frequency converting circuit for amplifying the received signal and converting the amplified GPS signal into a signal on an IF band, an analog-to-digital converter for converting the signal on the IF band into a digital signal, and a writing unit for writing the digital signal into a memory card in order to transfer the digital signal to the base station.

Abstract: A first radiation member 165 includes radiation conductors 166 and 167, an arm 168 and a lower connection piece 169 all integrally formed by blanking. A stub 170 is likewise integrally formed on radiation conductor 166. A second radiation member 171 includes radiation conductors 172 and 173, an arm 174 and a lower connection piece 175 all integrally formed by blanking. A stub 176 is likewise integrally formed on radiation conductor 173. A first loop comprised of radiation conductors 167 and 172, arms 168 and 174 and lower connection pieces 169 and 175 exhibits capacitive impedance at a wavelength for use. The overall length of a second loop comprised of radiation conductors 166 and 173, arms 168 and 174 and lower connection pieces 169 and 175 is set equal to that of the first loop. The second loop, however, exhibits inductive impedance at the wavelength for use by adjustment of the length of stubs 170 and 176. Adjusting stubs 170 and 176 enable control of a phase of a current flowing through the second loop.

Abstract: A detachable IC card applicable to a portable data processing device referred to as an "electronic organizer" is disclosed. The IC card is formed of microstrip lines formed on a dielectric substrate. An antenna receives an externally applied unmodulated carrier signal and guides the received signal to microstrip lines for impedance conversion. Cathode potential of a diode is varied in response to a data signal outputted from a CPU, so that the barrier capacitance of the diode varies. Accordingly, the carrier is reflected according to the data signal and radiated toward the electronic organizer main body through the antenna. An oscillator for data transmission is not required in the IC card, so that an internal battery having a large capacitance is not required, either. As a result, without increasing the size and weight of the device, radio transmission of data from the IC card can be accomplished.

Abstract: An AFC circuit stabilizes the frequency of an intermediate frequency signal to be applied to a demodulation circuit. A frequency conversion circuit responds to a local oscillation signal generated from a voltage-controlled oscillation circuit to convert the frequency of a digital modulation signal and applies the converted frequency to the demodulation circuit. A carrier reproduction circuit in the demodulation circuit reproduces the carrier of the intermediate frequency signal to output a synchronizing detection signal. The frequency of the reproduced carrier is frequency-divided by a frequency dividing circuit. A frequency division output thereof is counted by a counter for a definite period. Data is outputted from a microprocessor in response to a count output of the counter and the synchronizing detection signal, and the data is then converted into an AFC voltage by a D/A converter. The converted voltage is supplied as a control voltage to the voltage-controlled oscillation circuit.

Abstract: An MSK signal demodulating circuit including a carrier reproducing circuit for reproducing a carrier phase-synchronized with a component of a mark frequency or a space frequency of an MSK signal, a detector for performing synchronous detection of the MSK signal by means of the reproduced carrier, an identification circuit for converting an analog output from this detector into serial digital data, and a serial-parallel conversion circuit for converting the serial digital data into I, Q parallel data.

Abstract: A frame synchronization stabilizer for stabilizing frame synchronization of received data has a generation circuit for generating a reference pattern which is the same as a predetermined frame synchronization pattern contained in data being transmitted. The stabilizer further has a comparison circuit for comparing, bit by bit, a data pattern in a synchronization pattern area of each frame of the received data with the reference pattern from the generation circuit. The comparison circuit outputs a mismatch pulse each time when a mismatch bit is detected by the comparison, and outputs a match pulse each time when it is detected that the data pattern is fully matched with the reference pattern. The number of the mismatch pulses from the comparison circuit is counted by a first counter. The first counter outputs an out-of frame detection signal when a counted value exceeds a particular value and is reset based upon the match pulse from the comparison circuit.

Abstract: An AFC circuit stabilizes the frequency of an intermediate frequency signal to be applied to a demodulation circuit. A frequency conversion circuit responds to a local oscillation signal generated from a voltage-controlled oscillation circuit to convert the frequency of a digital modulation signal and applies the converted frequency to the demodulation circuit. A carrier reproduction circuit in the demodulation circuit reproduces the carrier of the intermediate frequency signal to output a synchronizing detection signal. The frequency of the reproduced carrier is frequency-divided by a frequency dividing circuit. A frequency division output thereof is counted by a counter for a definite period. Data is outputted from a microprocessor in response to a count output of the counter and the synchronizing detection signal, and the data is then converted into an AFC voltage by a D/A converter. The converted voltage is supplied as a control voltage to the voltage-controlled oscillation circuit.

Abstract: A mobile navigation system using a communication system between at least one mobile object and a key station. The navigation system includes a unit mounted on the mobile object for determining the position of the mobile object, and a unit mounted on the mobile object for transmitting data representative of the determined position to the key station via the communication system. The navigation system further includes a data base unit mounted in the key station for storing map data, a unit mounted in the key station for deriving map data of an area including the position of the mobile object from the data base unit, in response to the transmitted position data, a unit mounted in the key station for transmitting data including the derived map data to the mobile object via the communication system, and a unit mounted on the mobile object for displaying a composite image composed of the position data of the mobile object and the map data, in response to the transmitted data from the key station.

Abstract: A microwave data transmission apparatus adapted to transmit and receive information by microwaves, in which an identification tag is made smaller in size and lighter in weight to considerably improve the convenience in a setting operation for use in many applications. The apparatus can be applied for production control within a factory or can be used to recognize whether a person wearing an identification tag has entered or left a room.

Abstract: A microwave converter comprises circuit components formed on the outer surfaces of a three-dimensional body. The inner surfaces of the body constitute a grounding surface. A local oscillator is disposed on one of the inner surfaces. The three-dimensional body may be an electrically conductive body having a hollow space in which the local oscillator is disposed.

Abstract: A microwave data transmission apparatus adapted to transmit and receive information by microwaves, which the identification tag is made smaller in size and lighter in weight to considerably improve the convenience in setting operation for use in many applications, can be applied for the production control within the factory or the control for entering and leaving the room by a person having an identification tag.

Abstract: The SSB modulator according to the present invention is comprised of a driving voltage generator, a diode, a bias supply circuit, an impedance transformation circuit and an input/output terminal. The SSB modulator is arranged such that the impedance of the diode is changed by changing the driving voltage impressed across the diode, resulting in the mismatching of the impedance, which leads to generation of a reflected wave. Therefore, by changing the amplitude and the phase of the above-obtained reflected wave, SSB modulation is effected. Accordingly, the SSB modulator of the present invention, requiring no particular side band filter, is compact in size, light in weight and low in manufacturing cost, with a simple structure of the circuit.

Abstract: An antenna system includes a reflector which is a part of a paraboloid of revolution or parabolic cylinder, a primary radiator for clockwise circularly polarized wave, and a primary radiator for counterclockwise circularly polarized wave. The reflector is of geometrically asymmetrical shape to effect different reflection properties for clockwise and counterclockwise circular polarizations. The primary radiators are fixed at two different positions in the vicinity of the focus of the paraboloid reflector.

Abstract: An image suppression mixer of the waveguide type is disclosed which includes a waveguide signal input terminal at one end of a waveguide, a local oscillation input terminal at the other end of the waveguide, a mixer diode inserted within the waveguide and an IF signal output terminal connected to the mixer diode. At least the width of the waveguide on the side of the waveguide signal input terminal is selected to be a cutoff dimension for the image frequencies f.sub.m and the local oscillation frequency f.sub.1 the waveguide signal frequencies f.sub.2, the local oscillation frequency f.sub.1 and the image frequencies f.sub.m are correlated as f.sub.m <f.sub.1 <f.sub.s.

Abstract: A demodulation circuit for frequency modulated signals according to this invention comprises a variable phase shifter supplied with inputted FM signals, a narrow band pass filter having a band width narrower than that of the Curson band for the FM signals, a frequency discriminator, a filter allowing specific frequency components among the FM detected signals detected by the frequency discriminator to pass, and a phase adjuster to said frequency components, wherein said inputted FM signals are passed through said variable phase shifter said narrow band pass filter and then FM detected by said frequency discriminator, a portion of the detected output signals is passed through said filter allowing to pass the specific frequency components and the phase adjuster, thereafter, the phase shifter is controlled by said signals, the phase of the FM signals is controlled by the phase shifter in the direction of compressing the frequency deviation for said specific demodulated frequency components in the FM signals, and

Abstract: The threshold level for demodulating an FM signal, for instance a television picture signal, has been improved or lowered by adaptively restricting the bandwidth of the signal using an adaptive bandpass filter, and therefore, the picture quality and/or S/N ratio of the demodulated television signal has been improved. The adaptive bandpass filter has enough bandwidth when the signal level is sufficiently higher than the threshold level, but is narrow when the signal level is close to or lower than the threshold level. The bandwidth of the adaptive bandpass filter is adjusted according to the total power of the input FM signal and C/N (the carrier signal to noise) ratio. The improvement of the threshold level is almost 2 dB.

Abstract: The present invention relates to the improved demodulation system which improves the noise characteristics for the demodulation of a wideband television FM signal. A variable bandpass filter (8), the center frequency and the bandwidth of which are controllable, for improving C/N, is inserted at the output of a reference bandpass filter (7) in an FM signal path. The bandwidth of the variable bandpass filter (8) is controlled so that said bandwidth is wide when the input carrier level is high, and said bandwidth is narrow when the input carrier level is low. The center frequency of the variable bandwidth filter (8) is controlled so that said center frequency follows to the instantaneous frequency of the color sub-carrier component (3.58 MHz). Said color sub-carrier component is derived by a narrow-band bandpass filter (10) coupled with the output of said discriminator (9) for controlling the center frequency of the variable bandpass filter (8).

Abstract: The present invention relates to the improved demodulation system which improves the noise characteristics for the demodulation of a wideband television FM signal. An adapter for improving the ratio C/N is provided at the output of a bandpass filter (7), and the output of said adapter is applied to a discriminator (14) which demodulates the FM signal, through a limiter (13). The adapter has a variable bandpass filter (8), the center frequency and the bandwidth of which are controllable, and said variable bandpass filter (8) is inserted in an FM signal path. The bandwidth of the variable bandpass filter (8) is controlled so that said bandwidth is wide when the input carrier level is high, and said bandwidth is narrow when the input carrier level is low. The center frequency of the variable bandwidth filter (8) is controlled so that said center frequency follows to the instantaneous frequency of the color sub-carrier component (3.58 MHz).