Abstract: A thermometer or bouncing-ball LED display system provides a fast response, easily readable, quantitative indication of a variable. A received analog signal, representing the variable to be displayed, is effectively compared with an analog signal representing the present display indication. The difference therebetween is averaged over a sampling period. If this average difference exceeds a predetermined limit in either a positive or negative direction, the display indication is changed to reflect this difference. The sensitivity of the display can be selectively determined by increasing or decreasing the sampling frequency and the predetermined limit. The display system can be selectively operated in three different response modes. In a fast-attack, slow-release mode, the display indication is changed more rapidly in response to positive direction differences in the compare stage, than in response to negative direction differences.

Abstract: A swivel joint is designed to provide limited and controlled movement in two orthogonal planes running through its symmetrical center. The three major parts of the swivel joint are molded from a material composition of polycarbon-glass-teflon. A swivel top mounts to the object to be provided with controlled movement. A swivel bottom mounts to a support. The swivel top and bottom are held together by a large, curved wafer and a nut and bolt arrangement. The swivel top and bottom interact with each other to provide controlled limited movement in the two orthogonal planes, simultaneously.

Abstract: In a phase-modulated communication system utilizing voice-band communication channels wherein phase-jumps may be experienced, a phase-jump detector indicates the occurrence of such phase-jumps. A phase-jump corrector responds to the persistence of a phase-jump condition by correcting for it without requiring shut-down and complete reequalization of the transmission channel. Monitoring of the incoming signal for phase-jump occurrence provides a convenient signal quality indication that represents the magnitude of the error in the X and Y components of each received symbol.

Abstract: Disclosed is an automatic data communication system having communicating modems equipped with automatic equalizers. The equalizers respond to a first long equalization sequence automatically transmitted from another modem. In response to that long equalization sequence, the equalizer starts from a preset non-equalized condition and assumes a fully equalized condition. That equalized modem is also capable of automatically transmitting its own long equalization sequence to the other modem. Thereafter, second short equalization sequences are employed at the receiving modems to enable a memory storage associated with the automatic equalizers. The memory stores, in response to the long equalization sequence, signals which are indicative of the fully equalized condition. Accordingly, the equalizers do not have to start from a non-equalized condition for each new data message unless a dramatic distortion occurs.

Abstract: A phase modulation modem providing switch selectable speeds on voice-band channels utilizes four phase, modified eight phase, and optimized eight phase, two amplitude modulation techniques. A binary equalizer automatically corrects for envelope delay and amplitude distortion of the carrier signal caused by the voice-band channel. Each symbol time, the X-axis error and Y-axis error for the received symbol is determined by comparing the received X and Y components with stored ideal X and Y components for that symbol. These error X and error Y values are used to modify primary and secondary equalization constants. The equalization constants, thus modified during this symbol time, are used on the next received symbol to correct for the phase and amplitude distortion measured during past symbol times. This sequence is repeated for each symbol time. Preselected equalization constants are utilized on the first symbol received.

Abstract: Disclosed is an automatic data communication system having communicating modems equipped with automatic equalizers. The equalizers respond to a first long equalization sequence automatically transmitted from another modem. In response to that long equalization sequence, the equalizer starts from a preset non-equalized condition and assumes a fully equalized condition. That equalized modem is also capable of automatically transmitting its own long equalization sequence to the other modem. Thereafter, second short equalization sequences are employed at the receiving modems to enable a memory storage associated with the automatic equalizers. The memory stores, in response to the long equalization sequence, signals which are indicative of the fully equalized condition. Accordingly, the equalizers do not have to start from a non-equalized condition for each new data message unless a dramatic distortion occurs.

Abstract: An apparatus capable of transmitting digital data at high data rates over a communication link is disclosed. A carrier signal is modulated by serial groups of digital data signals to be transmitted during a plurality of successively appearing modulation periods. The data-modulated carrier is represented by a unique group of digital signals stored in a memory. The memory upon command, reads out a predetermined sequence of digital signals with each predetermined sequence representing the signal shape of a digital data modulated carrier signal which appears as though it has been passed through a narrow band limited linear phase network. The memory stores a predetermined number of such sequences of digital signals.The number of sequences is four in one preferred embodiment of this invention. In that preferred embodiment, each sequence occupies a spectrum frame which extends in time over four successive modulation periods.

Abstract: The present invention is directed to a method and apparatus for coding and decoding data so that it may be transmitted from point to point in either a baseband system or in a carrier system. The method and apparatus involves forming a multi-bit group of binary signals (bits) and transmitting such signals with at least one bit and a fractional part of another bit of the group in an encoding period. In a preferred embodiment of my invention a pair of adjacent encoding periods are employed to fully identify all the bits of a multi-bit group. My format requires less bandwidth than prior art binary formats. Furthermore, my format, when employed with a three level system, also requires less bandwidth than any known prior art three level system.The invention also includes an inherent error detection capability. Such inherent error detection is utilized at the receiver to automatically emit a decoded signal which has a high probability of being the correct signal that was transmitted.

Abstract: Modems having line verification circuitry for automatically advising that a direct distance dialed network has been connected between the communicating modems with the echo suppressors in the network disabled, is disclosed. The line verification circuitry is either identical for all modems or may be master/slave equipment. The line verification circuitry includes a first tone generator for emitting a unique tone for disablingthe echo suppressors in the telephone line. A communicating modem, upon receiving this unique tone activates a second tone generator that emits a different second tone which is not capable of disabling the echo suppressors but is capable of transmission through the telephone line when the echo suppressors are disabled. (63)disabling the at both modems respond to the first and second tones for automatically verifying the existence of the desired communication link.

Abstract: A data modem that operates to permit the concurrent high speed transmission/reception of digital data over two independent data links or systems, is disclosed. Data bits concurrently applied to a transmitting modem from two independent data sources are interlaced to form a stream of data bits that are effectively grouped as data words to be differentially phase modulated. Modulated data may be transmitted over ordinary voice grade telephone lines to a distant receiver modem at effectively twice the bit rate of the individual data sources. Successive groups of six interlaced data bits are divided into two groups of three bits which are uniquely identified by having a selected phase angle added to or subtracted from the differential phase angle for alternate groups of three bits.