A data converter applicable to data communications protects messages against errors and modifications by a third party. What is required for the detection of errors and modifications is simply causing a transmit station to add a particular pattern and a receive station to detect the particular pattern.

An adaptive system for binary data compression incorporating a coding scheme which is simple to implement, which limits codeword length and which can be implemented by software. Data compression is achieved by assigning four bit codes to the eight most frequently occurring characters in the data and eight or nine bit codes to the remaining characters wherein the code assignment is made according to a continuously updated evaluation of character frequency distribution. Run length encoding may be ...

A data plotter includes a table for supporting a record sheet, a carriage movable thereon along one orthogonal axis, and a recording device carried by the carriage and movable with respect thereto along the other orthogonal axis. Relative movement is effected between the carriage and table by means of a drive including a pair of spaced racks mounted on one, each meshing with a motor-driven pinion mounted on the other. The data plotter further includes an electronic synchronizing system for synch...

The present invention enables compression of digitized pictorial data to be achieved by comparing a data block of a predetermined size with a group of patterns relevant to that size held in a library. If a match is found the data block is represented by a code identifying the pattern on an output signal by a code identifying the pattern. If no match is found, the data block is sub-divided into smaller blocks which are compared with another group of patterns relating to the smaller block size. Th...

A data logger for logging data wherein stored incoming data is related to real time. Incoming data initially is stored at a relatively fine time resolution in a data memory. When the capacity of the data memory is exhausted, the stored data is rearranged into a relatively coarse time resolution form and then further incoming data is collected at the relatively coarse resolution. In the event of such a change of resolution, the relationship between the stored data and real time is not distorted.

A data terminal usable with a paging receiver mounted thereon is disclosed. The data terminal includes a whip antenna and a resonance circuit which is connected to the whip antenna. The ground of the resonance circuit is connected to the ground of circuitry mounted in the data terminal, so that the ground of the latter serves as a reflector of the whip antenna to enhance the antenna gain as well as the receive sensitivity. The antenna of the receiver is sufficiently remote from a clock oscillati...

The invention relates to compressing and transmitting data on a connection between two parties in a telecommunication system comprising at least one slow transmission channel, such as the air interface Um of the radio network. The data to be transmitted are assembled into frames (F) comprising a header section (1) and a data section (2). Prior to transmission, at least the header (1) or the data section (2) of at least some of the frames (F) are compressed. The transmitting party has available a...

A system for tracking the lineage of data in a database. Data within the tables are tracked by attaching lineage information to the data, preferably, by adding a lineage identifier to each row in a table. Data that share a common lineage can be identified by virtue of sharing a common lineage identifier. The lineage identifier can then be used to trace the source of the data, i.e., data having a common identifier share a common history. Preferably, the lineage data type is an identifier that is ...

A unique data recovery circuit which is able to recover transmitted digital data with a data clock embedded therein. No initial timing signals are required for operation of the data recovery circuit. Instead the data clock is recovered from the received data and used to synchronize the flow of data through the circuit. Noise pulses and other anomalous transients are rejected by the circuit so that the data output accurately corresponds to the data transmitted. Operation of the invention is achie...

When an induction coil which is supplied with an alternating current to output an induction current is moved along patterns formed on a data recording sheet, the magnitude of induction current generated in the induction coil changes in accordance with changes in the patterns. The change in the magnitude of the induction current is detected by a read device to thereby read information contained in the data recording sheet.