Abstract: Distance between two radio frequency devices is estimated by receiving a plurality of spread spectrum chirp signals frequency offset from one another, and evaluating the received plurality of spread spectrum chirp signals for relative phase shifts between the plurality of spread spectrum chirp signals. A fine propagation time is derived using the phase shifts between the spread spectrum chirp signals. A frequency domain despreading window is shifted to reduce the influence of time-delayed near multipath signals in receiving the plurality of spread spectrum chirp signals.

Abstract: The embodiments of the present invention disclose an apparatus for transmitting multi-ary error-correcting codes, an apparatus for receiving multi-ary error-correcting codes, a data transmission system, and relevant methods to simplify operations. The apparatus for transmitting multi-ary error-correcting codes includes: a multi-ary channel encoder, adapted to perform multi-ary coding for source data frames of a user to obtain encoded sequences; a symbol mapper, adapted to perform symbol mapping for the encoded sequences to obtain symbol sequences; and a spreading and interleaving unit, adapted to spread and interleave the symbol sequences. Moreover, a corresponding apparatus for receiving multi-ary error-correcting codes, a data transmission system, and relevant methods are provided.

Abstract: A baseband processing module includes an RX interface, a rake receiver combiner module, and may include additional components. The RX interface receives the baseband signals from an RF front end and creates baseband RX signal samples there from. The rake receiver combiner module includes control logic, an input buffer, a rake despreader module, and an output buffer. The rake despreader module is operable to despread the baseband RX signal samples in a time divided fashion to produce channel symbols including pilot channel symbols and physical channel symbols.

Abstract: A system is for encoding information on a passive surface acoustic wave (SAW) device. The system includes a requesting unit configured to wirelessly transmit an impulse signal. The impulse signal is a signal that includes only a single pulse. A SAW device has an interdigital transducer (IDT) configured to physically store coded data. The SAW device is configured to receive the impulse signal. In response to receiving the impulse signal, the SAW device excites the IDT to generate a coded signal that includes the stored coded data and frequency components at a fundamental frequency.

Abstract: A system is for encoding information on a passive surface acoustic wave (SAW) device. The system includes a requesting unit configured to wirelessly transmit an impulse signal. The impulse signal is a signal that includes only a single pulse. A SAW device has an interdigital transducer (IDT) configured to physically store coded data. The SAW device is configured to receive the impulse signal. In response to receiving the impulse signal, the SAW device excites the IDT to generate a coded signal that includes the stored coded data and frequency components at a fundamental frequency.

Abstract: A system is for encoding information on a passive surface acoustic wave (SAW) device. The system includes a requesting unit configured to wirelessly transmit an impulse signal. The impulse signal is a signal that includes only a single pulse. A SAW device has an interdigital transducer (IDT) configured to physically store coded data. The SAW device is configured to receive the impulse signal. In response to receiving the impulse signal, the SAW device excites the IDT to generate a coded signal that includes the stored coded data and frequency components at a fundamental frequency.

Abstract: Disclosed is a circuit for improved power management of a wireless device, comprising an input signal from an antenna, an oscillator, a mixer and a circuit for correlating. In a first analog embodiment of the circuit, the circuit for correlating comprises a surface acoustic wave (SAW) and the circuit further comprises an operational amplifier and a reference voltage. In a second digital embodiment of the circuit, the circuit for correlating comprises a digital correlator and the circuit further comprises a digital comparator.

Abstract: A wireless transmitter and receiver increase a desired/unwanted (D/U) ratio of a correlation output without increasing the number of data in an ultra-wideband direct spread pulse communication system for transmitting and receiving two series of data through different spreading code streams. In the spreading codes used in matched filters of the wireless transmitter, (2*N?2)-th and (2*N)-th values of a cross-correlation signal between first and second spreading codes are greater than 0, (2*N?3)-th and (2*N+1)-th values of an auto-correlation signal of the first spreading code are less than 0, and (2*N?3)-th and (2*N+1)-th values of an auto-correlation signal of the second spreading code are less than 0. The peak value of the cross-correlation signal does not need to be small, and since a value other than the peak value does not become large, the D/U ratio can increase.

Abstract: Apparatus, systems, devices and methods for providing an orthogonal frequency coding technique for surface acoustic wave sensors incorporating the use of multiple parallel acoustic tracks to provide increased coding by phase shifting and delaying a code sequence. The surface acoustic wave sensor includes parallel tracks with multiple reflectors with differing delay offsets to form a complex code sequence. The reflectors may be uniform, but alternatively could include fingers withdrawn, have reflector position modulation, differing frequencies or be spatially weighted.

Abstract: The present invention is a dramatically enhanced RF link for low-data-rate applications (1-100 bps), using one or more transmitters to communicate with one or more receivers, at dramatically enhanced ranges. The receiver of the present invention can rapidly search, detect, and lock in on narrow band signal transmissions, that may be present in a much larger frequency band and which may be changing frequency during the duration of the message. These receivers enable ultra-low noise floor detection of longer range, more highly attenuated, signal transmissions, by decreasing the receiver bandwidth.

Abstract: Disclosed is a circuit for decoding code phase modulated (CPM) signals, including a pseudo-noise (PN) code storage device, storing one or more reference PN codes, a peak detector having an output with decoded CPM data, and a correlation block, including a correlation multiplexer, a plurality of shift registers coupled to the correlation multiplexer, a selection circuit coupled to the plurality of shift registers, and a correlator coupled to the code storage device and correlation multiplexer. Also disclosed is a method for operating the circuit in two operating modes for decoding CPM signals.

Abstract: An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, internal dimensions of IDTs are inversely proportional to operating frequency, such that high frequency IDTs present significant manufacturing difficulties. Fabrication of IDTs for high frequency applications is simplified by exploiting a harmonic frequency SAW generated by IDTs. An IDT may therefore be designed according to fundamental frequency internal dimension criteria but can operate at a multiple of the fundamental frequency, thereby providing much higher frequency operation than conventional SAW systems. Operation of a second harmonic SAW system at 2.4 GHz based on a fundamental frequency of 1.2 GHz is contemplated.

Abstract: The present invention is a dramatically enhanced RF link for low-data-rate applications (1-100 bps), using one or more transmitters to communicate with one or more receivers, at dramatically enhanced ranges. The receiver of the present invention can rapidly search, detect, and lock in on narrow band signal transmissions, that may be present in a much larger frequency band and which may be changing frequency during the duration of the message. These receivers enable ultra-low noise floor detection of longer range, more highly attenuated, signal transmissions, by decreasing the receiver bandwidth.

Abstract: A surface acoustic wave sensor or tag having multiple transducer/antenna pairs each having a different center frequency. The bandwidth of each transducer/antenna pair is inversely proportional to the number of transducer/antennas pairs used and the bandwidth is the sum of the bandwidth of the transducer/antenna pairs. Implementing a SAW sensor or tag with multiple transducer/antenna pairs significantly reduces device losses and improves the performance of the device since the individual transducer/antenna pair's fractional bandwidth is reduced by the ratio of the system bandwidth to the number of transducer antenna pairs used in the sensor.

Abstract: A spread spectrum receiver whose de-spreading process based on transformed spreading codes is provided. Instead of de-spreading with original spreading codes, this approach de-spreads received signal with the spreading codes transformed from the original codes in order to eliminate the negative impact of system impairments such as frequency offset to a spread spectrum receiver. Before de-spreading with the transformed code, the received signal goes through the same transformation as the original codes do. After a transformation, the transformed codes may exist some undesirable property such as spreading code having DC content. An approach is given to cancel unwanted side effects relating the transformed spreading codes. The approaches are very effective for spread spectrum system based on frequency modulation scheme such as MSK.

Abstract: The ultra wide band communication system of the present invention includes a transmitter (station) and a receiver (station). The transmitter and the receiver employ spreading code comprised of code groups, which respectively comprise varied, auto-correlated codes. Consecutive information bits are spread and de-spread with differing code and the code groups are correlated with each other (e.g., orthogonal) so as to reduce channel impulse response estimation noise. At the receiver, subsequent channel estimates can be added or averaged with an initial channel estimate so as to reduce the channel impulse response estimation noise and thereby provide a relatively more accurate channel response.

Abstract: Provided is a method of compensating for energy loss and eliminating inter-symbol interference (ISI) and inter-chip interference (ISI) in wireless signals, and a rake receiver for wireless LANs adopting the same. The rake receiver compensates for energy loss of a CCK signal transmitted in a multi-path wireless channel environment and eliminates ISI and ICI from the received CCK signal because a DFE structure per chip used for calculating ICI components, is connected in parallel with a DFE structure per symbol, thus eliminating ISI and ICI components.

Abstract: In a spread spectrum system, methods and despreader architectures for despreading the received spreaded codes with the use of a single correlator and a single correlation code is provided. Before despreading the incoming received spreaded codes, a single correlation code is generated using a symbol from a set of symbols that has been mapped into a set of differential encoded PN codes. Despreading output samples for each received spreaded code are obtained by correlating the received spreaded code with this single correlation code. Correlation is accomplished by multiplying each received sample of the received spreaded codes with the correlation code samples and accumulating the products of this multiplication. After correlation, the index for the maximum or minimum peak of the despreading output samples for each code is identified. This index can then be mapped into a symbol corresponding to the transmitted information.

Abstract: A digital broadcast receiving apparatus for receiving a broadcast signal generated by combining sub signals modulated using a random sequence generated based on an initial value set in accordance with a frequency of a broadcast channel by a signal transmission control use signal and a main signal generated based on information source data and reproducing the information source data contained in the received broadcast signal.

Abstract: A system and method of carrier-less modulation is described in this disclosure that uses SAW filters as a modulator in addition to their conventional use as filters for band limiting an UWB system. This system and method is primarily designed to be used with any integer cycle, ultra-wide band or impulse type modulation and more particularly is designed to work with a method of modulation named xG Flash Signaling. This technique exploits the impulse response of the SAW filter by exciting the filter with a narrow pulse train producing a carrier-less impulse radio system with limited bandwidth, low average power, but high peak power.

Abstract: An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, internal dimensions of IDTs are inversely proportional to operating frequency, such that high frequency IDTs present significant manufacturing difficulties. Fabrication of IDTs for high frequency applications is simplified by exploiting a harmonic frequency SAW generated by IDTs. An IDT may therefore be designed according to fundamental frequency internal dimension criteria but can operate at a multiple of the fundamental frequency, thereby providing much higher frequency operation than conventional SAW systems. Operation of a second harmonic SAW system at 2.4 GHz based on a fundamental frequency of 1.2 GHz is contemplated.

Abstract: A structure of a spectrum spreading communication device which solves the problem with the conventional spectrum spreading communication using Barker codes, etc., and limits the rise of the side-lobe of a correctional signal independently of the order of information codes by use of a code sequence having a code length of at least 14. The spectrum spreading communication device uses a pseudo-noise code having code length of at least 14 and a self-correlation side-lobe of not greater than 3 as a pseudo-noise code of a direct spreading communication device which uses the pseudo-noise codes whose polarities are inverted so as to deal with also digital information. Thus, even when the pseudo-noise code length is 14 or more, the side-lobe of the correction coefficient can be restricted. Accordingly, the error rate of the spectrum spreading communication device is reduced and the processing gain is improved.

Abstract: A SAW communication device has a main IDT mounted on an SAW substrate to receive an RF signal received by an antenna and convert the RF signal to an acoustic wave which travels along the SAW substrate in opposite directions from the main IDT. At least two secondary IDTs are mounted on the SAW substrate on opposite sides of and spaced from the main IDT to receive and reflect the acoustic wave in a modulated form such that the modulated acoustic wave from one secondary IDT is delayed relatively to the modulated acoustic wave from a secondary IDT on the opposite side of the main IDT to the one secondary IDT. The main IDT is also operable to receive and convert the reflected modulated acoustic waves to a further RF signal with a concatenated waveform corresponding to the two modulated acoustic waves and transmit the further RF signal from the antenna.

Abstract: The contents by weight ratio of lanthanum oxide, gallium oxide, and silicon oxide, which are components, in the longitudinal cross-section and transverse cross-section of the straight part, excluding the shoulder part, of a Langasite single crystal ingot grown by pulling-up Langasite is within a range of ±0.05% with respect to the target amounts at all measured locations, and because of having a superior homogeneity in the content of components over the entire ingot, when used, for example, in a piezoelectric device such as an surface acoustic wave filter, has properties for industrial application that contribute to the stabilization of characteristics as well as reducing the costs.

Abstract: A digital filter or a receiver including a digital filter having at least two multiple stage shift registers. A plurality of multipliers corresponding in number to the number of stages in the at least two multiple stage shift registers receive as a first input an output from a corresponding stage of the at least two multiple stage shift registers. A tap weight shifter is coupled to a tap weight source to receive tap weights. The tap weight shifter is coupled to provide a second input to each multiplier. Each multiplier produces an output that is the product of inputs thereto. An adder sums the multiplier outputs to provide a sum output. The tap weight shifter then circularly shifts the tap weights and another multiply-add operation occurs. Several shift/multiply/add cycles may occur before data is again shifted into the at least two multiple stage shift registers, and another multiply-add operation occurs.

Abstract: In a filter circuit of the present invention, a partial quantization value is computed by a quantization circuit according to a spread code and others in a unit at an arbitrary stage, where an integrating value is increased. The partial quantization value is successively added by an adder formed by a counter and is transmitted to a unit of the following stage. In an adder of the following stage, an analog residual is computed by subtracting an analog converted value of the partial quantization value, that is obtained by a D/A converter, from the integrating value so as to suppress an increase in the analog cumulative value. With this arrangement, the cumulative value is increased according to an increase in the number of taps, so that an analog adder can reduce power consumption, which is caused by expansion of a dynamic range at the following stage.

Abstract: SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, internal dimensions of IDTs are inversely proportional to operating frequency, such that high frequency IDTs present significant manufacturing difficulties. Fabrication of IDTs for high frequency applications is simplified by exploiting a harmonic frequency SAW generated by IDTs. An IDT may therefore be designed according to fundamental frequency internal dimension criteria but can operate at a multiple of the fundamental frequency, thereby providing much higher frequency operation than conventional SAW systems.

Abstract: A spread-spectrum communication system utilizes spreading code sequences, which can be expressed as a matrix. The matrix of code sequences has or can be transformed to have a certain orthogonal relationship. In accord with the invention, a matched filter bank in a spread-spectrum receiver processes input signals that purport to contain the code matrix using two halves of an input stream matrix and only two of four possible quadrants of the code matrix as the reference inputs. Such processing produces two quadrants of a correlation signal matrix. It is then possible to determine the other two quadrants of the full correlation signal matrix from the known relationship with the two quadrants derived from the matching operations. The processing of only two of the quadrants of the signal matrix substantially reduces the number of computations and the amount of processor hardware needed to implement a matched filter bank to recognize the codes embedded in a received spread-spectrum signal.

Abstract: In a frequency converter, a phase-locked loop generates a local-oscillation signal having a low frequency, of a plurality of local-oscillation signals having different frequencies, based on an intermediate frequency beacon signal that results from mixing a predetermined beacon signal with the local-oscillation frequency signal. Even if the phase-locked loop is used to generate the low frequency local-oscillation signal only, a frequency offset and a phase noise taking place in remaining high frequency local-oscillation signals are compensated for or canceled out. The frequency converter thus results in a high frequency accuracy. This arrangement reduces the number of bulky, costly and power-consuming phase-locked oscillators, typically used in the quasi millimeter band or the millimeter band. A simplified, compact frequency converter is thus provided, reducing both installation and operating costs.

Abstract: In a frequency converter, a phase-locked loop generates a local-oscillation signal having a low frequency, of a plurality of local-oscillation signals having different frequencies, based on an intermediate frequency beacon signal that results from mixing a predetermined beacon signal with the local-oscillation frequency signal. Even if the phase-locked loop is used to generate the low frequency local-oscillation signal only, a frequency offset and a phase noise taking place in remaining high frequency local-oscillation signals are compensated for or canceled out. The frequency converter thus results in a high frequency accuracy. This arrangement reduces the number of bulky, costly and power-consuming phase-locked oscillators, typically used in the quasi millimeter band or the millimeter band. A simplified, compact frequency converter is thus provided, reducing both installation and operating costs.

Abstract: An ultrasonic coding modem for digital network communication comprises a transmitting device having a first piezoelectric substrate, and a receiving device having a second piezoelectric substrate. If a message digital-signal is applied to the transmitting device, a SAW is excited on the first piezoelectric substrate and is delivered as a coded digital signal into a digital network. On the other hand, if the coded digital-signal is received at the receiving device from the digital network, a SAW is excited on the second piezoelectric substrate. In this time, if the SAW excited on the second piezoelectric substrate is corresponding to the SAW excited on the first piezoelectric substrate, an output digital-signal, which is equivalent to the message digital-signal, is delivered from the receiving device. As a result, it is possible to keep a base-band communication secret.

Abstract: A matched filter having a set of registers to successively store a digital voltage. The matched filter includes a cumulative shift register, a number of exclusive-or circuits, and an analog adder. The cumulative shift register has a number of stages in which each stage has one bit corresponding to the shift register. The exclusive-or circuits each perform an exclusive-or function on each bit of the digital data and the one bit coefficient while the analog adder sums outputs from the exclusive-or circuits.

Abstract: A RAKE combiner apparatus uses a charge transfer element, which can permit a high-precision RAKE receiver to be constructed by a simple circuit structure, has lower consumption power, can allow the finger number to be arbitrarily set within a range of up to the number of taps of the matched filter and can implement a highly efficient RAKE process.

Abstract: SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, conventional SAW expanders and compressors typically have insertion losses greater than 20 dB, which can have a profound effect on an RF link budget in a communication system. Insertion losses are drastically reduced by using a single phase unidirectional transducer (SPUDT-type) instead of a conventional IDT as a SAW expander/compressor. A SPUDT-type reflects SAW components which are lost in conventional IDT designs so that a stronger SAW is directed toward a transmission element. In a receiver, a SPUDT-type directs a stronger SAW toward a compressor IDT.

Abstract: SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, conventional SAW expanders and compressors typically have insertion losses greater than 20 dB, which can have a profound effect on an RF link budget in a communication system. Insertion losses are drastically reduced by using a single phase unidirectional transducer (SPUDT-type) instead of a conventional IDT as a SAW expander/compressor. A SPUDT-type reflects SAW components which are lost in conventional IDT designs so that a stronger SAW is directed toward a transmission element. In a receiver, a SPUDT-type directs a stronger SAW toward a compressor IDT.

Abstract: A spread-spectrum system having a transmitted data rate determined by an error rate syndrome at a spread-spectrum receiver. A demultiplexer demultiplexes input data into a plurality of data channels. A plurality of FEC encoders FEC encodes the plurality of data channels, as a plurality of FEC encoded channels. A plurality of spread-spectrum processors spread-spectrum processes the plurality of FEC encoded channels as a plurality of spread-spectrum channels. The plurality of spread-spectrum channels preferably uses a plurality of orthogonal or quasi-orthogonal chip-sequence signals to define a particular spread-spectrum channel. A combiner combines the plurality of spread-spectrum channels as a code-division-multiplexed signal. At a receiver, a plurality of spread-spectrum despreaders despreads the code-division-multiplexed signal into a plurality of despread channels. A multiplicity of adders is electronically controlled by an adder-control signal.

Abstract: A surface acoustic wave matched filter for use in a spread spectrum communication system is disclosed. The surface acoustic wave matched filter includes a substrate having dispersity and is composed of a sapphire main body and a piezoelectric aluminum nitride. A tap distance L of an output side electrode is designed on the basis of a group velocity vg instead of a phase velocity vs in order to match the tap distance L with an input spread spectrum signal and to improve a correlation peak level of an output demodulated signal. When the tap distance L is set to satisfy a condition of vg/f1×0.97≦L≦vg/f1×1.02, a decrease in the correlation peak level of the matched filter can be improved from 7 dB to a value smaller than 3 dB, and S/N of the output demodulated signal can be increased. Thus, the disclosed device renders it no longer necessary to process the output demodulated signal by a complicated and power consuming circuit.

Abstract: An output side electrode of a surface acoustic wave matched filter with portions having different delay times between taps. The output side electrode may be provided by arranging parallelly a plurality of output side electrodes having different scales, different tap distances, or by forming output side electrodes in an inclined fashion or in a dog-leg shape viewed in a direction of an aperture length, or by arranging, between electrode fingers, thin films having different dimensions or thicknesses viewed in the direction of the aperture length, or by forming, between electrode fingers, recessed portions having different dimension or depth viewed in the direction of the aperture length.

Abstract: A spread spectrum demodulation circuit includes a correlation signal generator which generates a correlation signal from a reception signal to which a quadrature phase shift keying and a spread spectrum modulation are performed. First and second delay elements have different delay times, and delay the correlation signal to obtain first and second delay signals, respectively. First and second adders add the correlation signal and the first and second delay signals to obtain first and second addition signals, respectively. First and second distributors distribute the first and second addition signals, respectively. First and second multiplication circuits obtain first and second multiplication signals from distributed signals inputted from the first and second distributors, respectively. A data demodulation circuit demodulates the first and second multiplication signals to recover a transmission information signal.

Abstract: It is the object of the invention to provide a structure of a novel spectrum spreading communication device which solves the problem with the conventional spectrum spreading communication using Barker codes, etc. and limits the rise of the side-lobe of a correctional signal independently of the order of information codes by use of a code sequence having a code length of at least 14. The spectrum spreading communication device uses a pseudo-noise code having a code length of at least 14 and a self-correlation side-lobe of not greater than 3 as a pseudo-noise code of a direct spreading communication device which uses the pseudo-noise codes whose polarities are inverted so as to deal with also digital information. Thus, even when the pseudo-noise code length is 14 or more, the side-lobe of the correction coefficient can be restricted. Accordingly, the error rate of the spectrum spreading communication device is reduced and the processing gain is improved.