Other

Ctba Associates

Control Data Corporation

Harold R Walker

Russell J Welsh

Rand B Nickerson

Joseph A Cullity

Bohdan Stryzak

William J McKenna

Kenneth W Silvers

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 and near zero group delay, passes the near instantaneous modulation changes of phase in the carrier.

Apparatus and method for ultra narrow band wireless communications

The invention is a method for pulse position modulating signals which are synchronized to clocked bit periods using a clock comprising the steps of generating two, three or n signals to mark the presence of digital ones during corresponding n time slots occurring during the same bit period. The two, three or n signals are combined into a single data channel to utilize abrupt phase changes of pulses in a carrier signal at a carrier frequency, the phase changes having a very short duration to mark the presence of digital ones only. The combination of the n signals into a single data channel comprises gating each of the n signals in a sequence of serially delayed time slots corresponding to each of the n signals during a portion of the same bit period in the single data channel during time positions reserved for unexpressed zeroes.

Apparatus and method for data rate multiplication

A method of modulating a phase reversing pulse train including a plurality of signal pulses each having an associated period of a given temporal duration to encode a multiplicity of input data bits each having a data state, and prevent losses of clock timing. The method includes the steps of: identifying select ones of the input data bits which repeat the data state of a respectively preceding one of the input data bits; identifying select ones of the pulses which correspond to the select bits; and, alternately shortening and lengthening the periods associated with the select ones of the pulses.

Single sideband suppressed carrier digital communications method and system

A wireless digital transmission and receiving method combines phase reversal keying with pulse position modulation. Modulation of a transmitted signal implements pulses that are of extremely short duration to indicate ones and zeros. These pulses can be as narrow as one cycle of the carrier frequency. As such, they often appear as missing cycles or pulses in a sequence of carrier cycles. The method synthesizes a sideband with no carrier or other sidebands from the carrier of an input signal. This synthesized sideband is represented by a broad sinx/x spectrum with a principal power peak at the modulated frequency and numerous weaker peaks of varying frequencies and peak levels. The time duration of these smaller peaks is such that they have negligible mean power levels. Thus, the synthesized signal can withstand the degradation caused by multipath interference and fading. The weaker peaks also do not cause measurable interference with other communications devices. The smaller peaks can have amplitudes far below the noise level of the system. Hence, the smaller peaks are not a necessary or an important component of the signal. The result is a strong signal in the form of a synthesized single sideband with all the useful modulation in the brief phase reversal period with a constant signal in the remainder of the bit period that can be used to establish a reference to create uniform time rise and amplitude.

Digital modulation device in a system and method of using the same

A method for transmitting 'biphase' encoded digital signals including the steps of setting an aperture corresponding to a data bit; dividing said aperture into a plurality of segments; setting a first segment, selected from said plurality of segments of said aperture, dependent upon whether the bit is a digital one or zero; setting a second segment, selected from said plurality of segments of said aperture, so as to fit the remaining aperture of the data bit; and, transmitting said first and second segments of said data bit; wherein a narrow spectrum results containing no low frequency components and separated from 0 Hz by an amount equal to the data rate or 1/2 the data rate.

Digital modulation employing single sideband with suppressed carrier

An improved binary data communication system employs an improved VPSK encoding procedure wherein each input data bit has a bit period of M clock periods, and the data bit polarity changes are phase shift key coded with waveform widths of M/M, M+1/M, and M+2/M bit periods wherein M is an even integer greater than 3. Each of the data bits (except the last one in an encoding cycle) is encoded in an encoding signal which switches back and forth between '1' and '0' polarities and has assigned widths representing whether or not the polarity of the data bit is changed from that of the previous data bit, and whether it is the last (M-1th) polarity change in the encoding cycle. At the receiving end, a complementary procedure is used to decode the encoded signal. For transmission, the encoded signal is filtered for higher order harmonics and integrated in order to provide a sine wave output shifted 90 degrees in phase. Upon reception, the received signal is differentiated and a zero crossover detector is used to regenerate the encoded signal for decoding. The improved encoding technique can achieve Nyquist efficiencies of 10, 12.6, and 15.3 bits/Hz-bandwidth, or higher, for M equal to 6, 8, and 10 modulation levels, respectively. The encoded signal spectrum fits typically within about 1/6 of the bandwidth of the baseband NRZ signal. The encoded signal is particularly useful for transmission at high data rates in telephone, RF modulated carriers, and other transmission systems.

High speed data communication system using phase shift key coding

A data gathering system includes a plurality of remote units which are controlled from a central location. Each of the remote units is attached to a television receiver which is generally but not necessarily attached to a cable system. Each of the remote units can function to determine which of several TV modes is in use as well as to store TV channel selector data, data from an optical input device, and/or data input by viewers representative of the composition of the viewing audience. The data is stored for either later collection by a portable data collector, or for direct transmission via telephone to the central location. A video message for a TV viewer, such as a survey, may be transmitted from the central location and stored at the remote units, for later display on the TV receiver associated with the remote units. Substitution of alternate programming information may also be achieved by the central control point on selected of the remote units.

Television and market research data collection system and method

There is disclosed a high speed data transmission system for transmitting a binary data signal over a communications path. The binary data signal is clocked at a given period. The system comprises encoded means responsive to a binary NRZ input data signal to provide at an output an encoded digital signal having time periods greater than multiples of the clock period, whereby the encoded signal occupies a lesser effective bandwidth than the NRZ signal would occupy. There are balanced modulator means having an input responsive to the encoded signal and another input adapted to receive a carrier frequency to provide at an output a double sideband suppressed carrier signal. Coupled to the output of the balanced modulator are narrow bandwidth filtering means including first low pass and second high pass parallel filter paths each having a common input terminal coupled to the output of the modulator. The ouputs of the low and high pass filters are symmetrically combined to provide a narrow single sideband signal for transmission characterized in that transitions between binary levels in said encoded signal are manifested by distinct phase changes in said single sideband signal.

High speed binary data communication system

A data gathering system includes a plurality of remote units which are controlled from a central location. Each of the remote units is attached to a television receiver which is generally but not necessarily attached to a cable system. Each of the remote units can function to determine which of several TV modes is in use as well as to store TV channel selector data, data from an optical input device, and/or data input by viewers representative of the composition of the viewing audience. The data is stored for either later collection by a portable data collector, or for direct transmission to the central location. A video message for a TV viewer, such as a survey, may be transmitted from the central location and stored at the remote units, for later display on the TV receiver associated with the remote units. Substitution of alternate programming information may also be achieved by the central control point on selected of the remote units.

A data gathering system includes a plurality of remote units which are controlled from a central location. Each of the remote units is attached to a television receiver which is generally but not necessarily attached to a cable system. Each of the remote units functions to determine which of several TV modes is in use as well as to store TV channel selector data and data from an optical input device. All this data is stored for later transmission by each of the remote units to a central data collecting point. A video message for a TV viewer, such as a survey, may be transmitted from the central location and stored at the remote units, for later display on the TV receiver associated with the remote units. Substitution of alternate programming information may also be achieved by the central control point on selected of the remote units.

A telemetering system useful for telephone installations. A normally open switch is placed between the line and telephone set. A ringing signal permits sensing apparatus to deliver a coded message to the line between the first and second rings, and the normally open switch is closed before the second ring. Ordinarily calls are delayed for the period of one ring and calls seeking data collection are disconnected before the normally open switch closes. Alternatively data may be delivered to a station associated with the telephone set.

Growing community of inventors

Edison, NJ, United States of America

Harold R Walker