Abstract: With this method and equipment the sensitivity of receivers, whose gain control criterion is a constant noise signal level, can be controlled independently of the received data signal, so that the reception of long datastreams is possible. For this purpose a diode (D1) is provided, whose anode is connected to a voltage source, and whose cathode is connected with a current source (Q4) and with the cathode of a second diode (D2) whose anode is connected to a capacitor (C12). A voltage is applied across the capacitor (C12) which is smaller in the rest state than a second voltage applied via the first diode (D1), so that the second diode (D2) is reverse-biased. After reception of a data signal a discharge pulse (EP) is generated dependent on an output of a signal detector, through which the second voltage is reduced to a value that is smaller than the first voltage.

Abstract: With this method, a CSMA/CA protocol can be used for the transmission of data by means of infra-red light or radio (or other non-hard-wired transmission media). For this purpose a communicator that has a transmit requirement and has not yet received a bit identifies itself as an initiating communicator, and one that has no transmit requirement but has received a bit identifies itself as a receiving communicator. At the start of data transmission the initiating communicator sends a double length start bit (D) representing its identity and then waits a defined time (tc), during which the receiving communicator sends back an echo in the form of a single length start bit (B). The initiating communicator waits after each bit transmitted for the echo and compares this on receipt with the transmitted bit, its transmission being interrupted after a mismatch. After the data transmission, and provided there is no further transmit requirement, the identities of initiating and receiving communicators are removed.

Abstract: With this method protection against unauthorized access can be accomplished centrally so that less memory capacity and calculation time are needed for testing the right-of-access. By this the message traffic in the whole network is constantly intercepted by a central supervision device (SV). A table is stored in the central supervision device (SV) whereby upon entry of a message, the central supervision device tests the right-of-access of the message sender (SE,PC) to the message receiver (AK) with the aid of data in the table and a predetermined portion of the information contained in the message. In case of unauthorized access, the supervision device causes the message to be rendered ineffective.

Abstract: With this method the performance of full-duplex systems can be achieved with transmission of information using infra-red light or radio (or via other transmission media not involving hard wiring). For this purpose the two datastreams to be transmitted in opposite directions are brought to the same transmission rate. The time period (ta) between the beginnings of successive bits of a datastream are split during transmission into two equal halves (tb, tc), whereby the bits are transmitted during the first half (tb). A transmitting communicator switches to receive immediately after the transmission of a bit, whereas a receiving communicator switches to transmit after the receipt of a bit if it needs to send information, so that the transmitted bits of one datastream are sent during the second half (tc) of the opposing datastream.