Abstract: A code phase setting method in a PN coder which includes a shift register is provided. According to the method, an initial value is set in the shift register and a direction is selected among two directions in which direction a value in the shift register is shifted. Then, a code phase is set by shifting the initial value in the direction a necessary number of times.

Abstract: A cost-effective continuous phase logic-based modulator and demodulator are provided to allow communications using binary frequency shift keying (BFSK) as well as M-ary FSK techniques. The modulator of the 1-bit precision modem architecture is based on a 1-bit precision numerically controlled oscillator (NCO), which provides complete programmability with respect to a frequency of the 1-bit precision logic-based modulator and/or demodulator. The 1-bit precision NCO includes an adder and a phase accumulator register which is clocked by a master clock signal. A two-input multiplexer has a single bit symbol value to generate BFSK, or larger input multiplexers can be implemented to provide M-ary FSK. The output of the 1-bit precision NCO is upconverted to an intermediate frequency using a simple logic function, i.e., XNOR logic. Alternatively, the intermediate frequency may be arrived at without the need for upconversion by directly utilizing a harmonic alias at a desired IF frequency.

Abstract: A system for transmitting, receiving, recovering, and reproducing digitized samples of analog signals while concealing unrecoverable digitized samples of analog signals to maintain a level of fidelity in reproducing the analog signals. The digitized samples of the analog signals are burst transmitted such that the probability of interference with the transmission and thus corruption of the digitized samples of the analog signals is minimized. The digitized samples are received without synchronizing a receiving clock with a transmitting clock to capture the digitized samples of the analog signals. The digitized samples are converted from various sampling rates to digitized samples of the analog signals having a rate. Any large groups of digitized samples that are in error or corrupted in transmission are softly muted to avoid annoying clicks.

Abstract: A DTMF signal generator simplifies frequency characteristic design of a telephone line interface so as to make it easy to carry out alteration of a low tone group frequency component and a high tone group frequency component of a DTMF signal, and to lower cost by doing away with the need for a D/A converter. There are provided first and second sine wave generators (201 and 202) for respectively generating sine waves of specific frequencies, a combining circuit (210) for combining and outputting the outputs of the first and second sine wave generators at a specified ratio, a PWM modulator (214) for generating pulses at a width corresponding to the output of the combining circuit, and a filter (211) for removing undesired frequency components included in the output of the PWM modulator. The combining ratio of the combining circuit is variable.

Abstract: A method of detecting, blind, the coding mode used to encode digital data, for data transmitted in frames of n bits, partially subjected to a convolutional coding. A soft syndrome value is calculated over a sequence of bits representative of a transmission error probability in these bits, and a likelihood value V(&agr;,&bgr;), where &agr;, &bgr; denote the number of coded bits and non-coded bits respectively, is then calculated on the basis of the mean value m and the variance &sgr; of the distribution of the absolute soft syndrome values. The likelihood value V(&agr;,&bgr;) is maximised as a function of &agr; or &bgr; which makes it possible to determine the coding mode used on the basis of the corresponding values &agr; or &bgr;.

Abstract: The present invention provides an adaptive filter and a learning method therefor to eliminate real output signals generated by input signals and an environment signal response. The adaptive filter receives the input signals from an input signal source and generates estimated output signals according to an filter coefficients and the input signals. The first step of the learning method is storing the input signals and the real output signals within a past time period. Then, a predictive input signal and a predictive output signal are generated according to the input signals and the real output signals in the memories, respectively. Finally, the filter coefficients is updated according to the predictive input signal, the predictive output signal, one of the input, signals and one of the real output signals, causing the estimated signals to approximate the real output signals.

Abstract: A sigma delta modulation device and method for filtering high frequency intermediate frequency signals. A summing amplifier receives the analog intermediate frequency signal, and provides to a surface acoustic wave filter (SAW) an analog signal which is to be converted to a digital quantity. A quantizer digitizes the signal to produce a digitized intermediate frequency signal. A digital to analog converter provides a feedback signal from the quantizer output signal, to the summing amplifier to form a sigma delta modulation device. The SAW filter provides for high stop band attenuation of signal images within the intermediate frequency signal, and produces a low noise signal with substantially no intermodulation products.

Abstract: Apparatus and method for reducing the range of a transmission signal comprising a plurality of digitally represented complex communication signals, including means for estimating the magnitude of each of the plurality of complex communication signals, based on the complex components, means for determining at least one scaling factor based on the plurality of determined amplitudes and means for reducing the amplitude of the respective complex signal components. The system is accommodated to operate at very high frequency and may advantageously be provided with a circuit determining the amplitude of each of the complex signals using the CORDIC algorithm. The system may further be provided with means for scaling the magnitude of each of the complex components in a coarse scaling step and a fine scaling step. The system allows to effectively reduce the amplitude of the transmission signal eliminating the need for larger and more expensive amplifiers.

Abstract: Signals from antennas A and B are alternately switched by an antenna switch at a predetermined rate. Then, the signals from the antennas A and B are alternately input to a wireless receiving unit. The wireless receiving unit orthogonal-signal-detects the signals received by the antennas A and B, and inputs the detected signals to a branch selecting unit. The branch selecting unit extracts only the signals from either of the antennas from the signals obtained from the antennas A and B, which are alternately arranged in time series, and transmits the extracted signals to a matched filter. A searcher obtains despreading timings from correlation values, and stores the obtained timings in two memories. The searcher obtains despreading timings with large correlation values, and transmits the timings to a despreading unit to perform RAKE reception.

Abstract: A CDMA reception apparatus has a plurality of fingers and performs RAKE reception by RAKE-combining outputs from the plurality of fingers. The apparatus includes a multi-path detecting section and delay profile generating section. The multi-path detecting section detects a multi-path consisting of a plurality of radio waves arriving with some delay times by despreading a reception signal. The delay profile generating section generates a delay profile by obtaining the reception power levels of all reception signals in the multi-path detected by the multi-path detecting section. A difference di in level between the signal having the ith highest level and the signal having the (i+1)th highest level of the data of the delay profile is obtained. The operation of a finger corresponding to a signal having a low level is stopped on the basis of the difference di and a predetermined threshold dTH.

Abstract: A method and apparatus for transmitting and receiving digital data in a noisy environment. Digital data is transmitted with a degree of noise immunity by generating and transmitting a reference signal along with the transmitted digital data signal. The reference signal has a voltage level between a logic level low and a logic level high of the digital data signal. The reference signal can be used to identify the center point of the transmitting device logic levels. Furthermore, the reference signal allows the receiver to track and compensate for noise introduced at the transmitter of the digital data signal.

Abstract: A process and system for the transfer of information, which is suitable in particular for digital information transfer. At least one information signal is created, consisting of at least one reference component and at least one information component, wherein at least one of these components has a temporally continuous frequency change during the transfer and, in addition, the reference component and the information component form discrete states for the provision of bit patterns. After receiving, the at least one component with frequency change is transferred into constant intermediate frequencies. From the spectrum of the constant intermediate frequencies, in each case the best-suited signal components are selected, separated as constant frequencies from interference portions and evaluated with regard to the relevant information parameters. This allows a signal transfer with high quality and high transfer rate, even over great distances, for example, under water.

Abstract: A stream of incoming digital signals (Ia) is split (10) into a plurality of derived streams (Ib) that are sent over respective transmission links (R). The derived streams transmitted in this way (Ic) are then bundled again (20) to form a stream of outgoing digital signals (Id). At the transmission end, symbols are inserted into the derived streams (Ib) simultaneously and at constant intervals (T), in order to subdivide the transmitted information into packets of equal duration and aligned in time when being transmitted. At the reception end, the above symbols associated to the transmitted derived streams (Ic) are generally time-shifted as a consequence of the transmission over the various transmission links (R). At the reception end (20) the time alignment of the above symbols is recovered so as to recover the time alignment of the various transmitted derived streams (Ic), so that the subsequent bundling can take place on the streams correctly time-aligned.

Abstract: The invention relates to methods and apparatus for Turbo Code interleavers for use with third generation code division multiple access (3G CDMA) data. The apparatus includes a memory for receiving and temporarily storing the data, a counter and a clock coupled to the memory and counter for synchronization. The apparatus also includes a table containing a addresses that are selected by the counter. A puncturing device coupled to the table discards addresses if they are greater than a frame size. A buffer is coupled to the memory and the clock. The memory is configured to retrieve data from the selected addresses which are not discarded and forward it to the buffer for output.

Abstract: A system for transmitting, receiving, recovering, and reproducing digitized samples of analog signals while concealing unrecoverable digitized samples of analog signals to maintain a level of fidelity in reproducing the analog signals. The digitized samples of the analog signals are burst transmitted such that the probability of interference with the transmission and thus corruption of the digitized samples of the analog signals is minimized. The digitized samples are received without synchronizing a receiving clock with a transmitting clock to capture the digitized samples of the analog signals. The digitized samples are converted from various sampling rates to digitized samples of the analog signals having a rate. Any large groups of digitized samples that are in error or corrupted in transmission are softly muted to avoid annoying clicks.

Abstract: A down-converter converts an amplitude modulated high frequency signal into a low frequency or baseband signal. A first mixer (30, 32) mixes the high frequency signal into a composite signal having an in-phase component and a quadrature component. A complex bandpass filter (34) bandwidth limits the composite signal into a bandwidth limited signal with an in-phase component and a quadrature component. A second mixer (36, 38) mixes the bandwidth limited signal into an intermediate signal with an in-phase component and a quadrature component, and an adder (40) adds one component of the intermediate signal to the other. A similar up-converter performs the reverse process.

Abstract: The invention relates to a simple method of forming a set of constellations of average power levels lower than a fixed threshold PMAX. The invention is applied to all the cases where the points of the constellations to be formed are not equiprobable, and thus the expression of the average power of the constellation set has a complex form. The invention comprises forming a first set of constellations by considering that the points of each constellation are equiprobable, which enables to form the constellations independently of each other. The exact value P of the average power of the set of constellations thus obtained is then calculated for verifying whether P>PMAX. In that case, the constellation set is modified by suppressing one or various points in one or various constellations so as to obtain an average power P<PMAX for said set.

Abstract: A method and a receiver for reducing adjacent-channel interference to a digitally modulated receive signal evaluates error rates of the receive signal associated with different receive bandwidths of the receive signal. The receiver selects a preferential bandwidth among the different bandwidths based on a suitably low error rate associated with the preferential bandwidth. The selection of the different bandwidths is achieved by digital signal processing that weighs desired data bits representing a desired bandwidth differently than rejected data bits representing a rejected bandwidth.

Abstract: A Global Positioning System receiver includes an intermediate frequency (IF) processor configured to downconvert broadcast signal to generate a first channel signal which is further downconverted to recover a PRN signal by an angle rotator. The receiver further includes a signal generator configured to generate N gated PRN signals. The N gated PRN signals are generated based on a local replica PRN signal time-divided by M intervals within a chip period of the local replica PRN signal. N and M are positive integers. A number of correlators is also provided. Each of which the correlators are configured to multiply a respective one of N gated PRN signals with the PRN signal to generate a number of correlation values. The correlation values are utilized to monitor distortions in the broadcast signal and/or to track the carrier frequency signal. Further, a corresponding method is also provided.

Abstract: A radio receiver (10) processes a carrier signal having a Doppler shifted frequency and carrying a coded signal having variable phase and amplitude. The coded signal is divided into a preamble portion and a message portion. A memory (23) stores samples of the coded signal representing at least some of the predetermined symbols of the preamble. A logic unit (16) divides the stored samples into a plurality of sample groups and identifies one sample group having the minimum variation of envelope amplitude. That sample group is used to provide additional samples by which the Doppler shift of the carrier frequency is estimated (70). The coded signal is delayed by a delay operation (100) and has its Doppler shift reduced. The Doppler reduced coded signal is processed by a filter operation (120) and a demodulator (130).