GB1328821A - Information transmission systems - Google Patents

Abstract

1328821 Data transmission systems HONEYWELL Inc 2 Sept 1970 [13 Oct 1969] 42048/70 Heading G4H A data transmission system comprises a central station and a number of remote stations which transmit information messages to the central station, each message comprising two parts namely a second part containing the information being transmitted and a first part which instructs the central station of the form in which the information contained in the second part is transmitted, and processing apparatus 44 at the central station for selectively directing the second part of each message into one of two processing channels. The system may be used to monitor air conditioning apparatus including, for example, temperature responsive resistance elements 32, 34, 40 located at remote buildings. Transducers 33 and 35 convert the measured resistance into a train of pulses, the frequency of which depends on the value of the resistance and into a binary coded decimal signal respectively. These signals which form the second part of a message are fed to message receiving and transmitting apparatus 25, 30. The second part of each message is accompanied by a first part which comprises six bits for informing the central station of the type of data in the second part, e.g. that the data is temperature data, and a single bit which informs the central station that the data is in binary coded decimal or variable frequency pulse train form. The apparatuses 25, 30 are connected by a coaxial line 15 to the central station and a leased line such as a telephone line 21 connects similar apparatus 31 to the central station. Data in the pulse train form is directed to the processing channel which includes a converter 45 to convert the data to binary coded decimal form whilst data already in the latter form is fed to the other processing channel for direct supply to indication apparatus 43.