A binary data stream of cadence f to be transmitted by PSK (phase-shift keying) modulation is split into two pulse sequences, composed of alternate bits of that data stream, which are translated into 180.degree. phase shifts of respective sinusoidal carrier waves in quadrature with each other, the frequency f of the two carrier waves being the reciprocal of the pulse width 2/f of the two pulse sequences in a specific instance. A pair of interleaved trains of trigger pulses, each coinciding with ...

Apparatus for and the method of providing three channel, eight phase data modulation and demodulation whereby the system may be used for either two or three channels with no detrimental effects in either mode of operation due to the additional circuitry. The invention discloses additional apparatus for connection to a conventional two channel, four phase system to produce a three channel, eight phase system. The coding of the eight phase system modifies the basic phase change of a two channel, f...

A method and apparatus for coding binary data is disclosed in which the coding is accomplished in a first embodiment by shifting the phase of a carrier by a first predetermined phase angle in response to detection of a pair of adjacent like bits and by a second predetermined phase angle in response to detection of the complement of the aforementioned pair of adjacent like bits. The carrier is shifted by a third predetermined phase angle in response to detection of either of the alternate three b...

A method of .pi./4-shift QPSK modulation and .pi./4-shift QPSK modulator are provided. The modulator address symbols from a Precursor section of a register to a first memory portion and from a Postcursor section of the register to a second memory portion at odd times and, address symbols from the Precursor section to said second memory portion and from said Postcursor section to said first memory portion at even times. The modulator uses reversed addressing for Postcursor symbols in accessing th...

A modulator for differentially encoded phase-shift keyed digital data is implemented entirely by digital means. Baseband serial binary data are illustratively transformed into dibit pairs which are assigned discrete quaternary carrier-wave phase shifts. A "staircasing" shift register whose weighted outputs are combined to form a quantized phase-modulated carrier wave is advanced by a relatively high-speed counter through a frequency divider network. The division rate of the divider is selectivel...

A PSK modulator employs a waveform of the overlapped raised cosine type which results in reduced adjacent channel interference. Waveforms of the overlapped raised cosine type include the overlapped raised cosine waveform itself as well as waveforms substantially similar thereto. Such waveforms can be produced, in a PSK modulator, by employing a Thomson filter with a single attenuation pole. Employing such a filter with a time bandwidth product (BT) of 1.2 provides the overlapped raised cosine wa...

The disclosure is directed toward improved methods and apparatus for producing PSK signals. Commonly, such signals as Differential Quadrature Phase Shift Keying (DQPSK) are produced by coupling the outputs of an encoder to finite impulse response (FIR) filters. The filters shape the path that the signal takes between the transmission of one symbol and the next symbol The present disclosure discloses a method of generating a signal so that the path taken between transmitted symbols is determined ...

A method and apparatus are provided that yields bandwidth efficient low bit rate communication of digital signals in a noisy channel. According to one aspect of the present invention, the invention includes demultiplexing a received input bit stream to divide it into a first block and a second block, convolutionally coding the first block, block coding the second block, mapping the convolutionally coded first block to a sequence of three-bit symbols, so that the bits of the convolutionally coded...

A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has a baseband processor which is coupled to storage means for the baseband functions. The baseband processor is direct access coupled to a modem processor whereby the two processors may communicate with each other. The modem processor generally acts as the master in the system, although lock-out means may be used in certain circumstances. The signal from the modem processor is converted...

A wireless digital transmitting and receiving method and apparatus combining abrupt phase change modulation with an ultra narrow band filter to remove the sidebands, resulting in a single frequency being transmitted to carry the data. The method examines and detects the changes in the carrier product only, after filtering to remove or reduce all sidebands, to obtain a usable signal. Only a single frequency with phase changes is transmitted. An ultra narrow band filter, having a rapid rise time a...