Versatile data-signal switching apparatus for controlling the switching and time-division multiplexing of signals appearing on a multitude of data input channels, comprising a pulse generator and a timing circuit for forming a sequence of pulses at a time-slot rate and sequences of pulses recurring at each of several required sampling rates, a working store which can store one address word for each sampling rate, address resetting means responsive to each pulse of each sequence so as to replace an address word in the working store with a starting address word associated with the rate of the sequence to which the pulse belongs, a time-division multiplex gating circuit, and a logic circuit constructed to select one address word from the working store during each time-slot, apply the selected word to the multiplexer address input, and add a prescribed increment to the selected word in the working store. The time-slots may be subdivided so that actions on address words associated with a given sampling rate are done in an associated subdivision of each time-slot.

An operator console, a general purpose digital computer and a radio set irface are connected to perform the modulation and demodulation of the differential coherent quadrature phase shift signal used to transmit the digital information over a computer-to-computer radio link. The console is used to initiate communications and to control and monitor link operation. The computer performs all of the signal processing and control functions. The radio set interface performs analogue-to-digital (A/D) and digital-to-analogue (D/A) conversions for the received and transmitted signals, respectively. The programmable data terminal set (PDTS) also controls the data link operation and sequencing and tests its own performance during operation.

The system includes: a number of subassemblies, each containing a set of switches connectable at their pair of inputs to different sources of analog signals and containing a multiplexer/decoder having outputs connected to different switches for their selective actuation; a differential amplifier having a pair of inputs connected to the pair of outputs of all of the switches; analog/digital converter means having its input connected to the output of the amplifier and having outputs providing multi-bit digital information; and control means that provides various functions.

A communication system with baud rate detection capability. In a preferred embodiment of the system, the system includes a processor, a plurality of terminals, and a communication device for coordinating transmission of communications between the processor and terminals at a variety of baud rates. Each baud rate of a system corresponds to a unique baud-rate-code and each baud-rate-code is an interval of time. The signal by which each communication is transmitted includes a baud-rate-code as represented by at least one time interval between signal state transitions The communication device detects the signal state transitions representative of the baud-rate-code and concurrently records the time of occurrence of each detected transition. From a pair of recorded times, a transition interval is computed and correlated with one of the baud-rate-code time intervals to identify a correlated baud-rate-code. The baud rate corresponding to the correlated baud-rate-code is indicated and a transmission of a communication is decoded in accordance with the indicated rate.

A digital seismic telemetry system for recording seismic data from a plurality of seismic signal detectors positioned at selected detector stations. The system includes a plurality of remote units, each of which is positioned at a distinct detector station to receive seismic data from the detector at that station. The remote units each include a storage device for storing seismic data from the detector in digital form, and a remote transmitting unit for transmitting the stored seismic data from the storage device to a master recording unit for recording. A master control unit operably connected with each of the remote units controls the acquisition and the transmission of seismic data from the remote units to the master recording unit and limits the amount of data transmitted at any given time to optimize the bandwidth requirements for the data transmission.