Abstract: The invention relates to a portable one-way radio pager comprising pager means (4, 5, 6) for receiving radio messages, a memory (8) for storing messages, a screen (2), a keypad (3), a CPU (7), and a loudspeaker (9). The CPU is designed to recognize specific "certification primary code" messages and to cause an encoded sound signal to be emitted by the loudspeaker as a function of a secondary code keyed in by a user via the keypad, and of an additional code accessible to the CPU. The encoded sound signal enables the user to be identified.

Abstract: To decode a multivalent electrical signal capable of taking up a number n of states greater than two, an electrical magnitude representative of the state of the signal is measured successively in successive pause periods of constant duration T during which said electrical magnitude remains substantially constant. The measurements are performed at constant time intervals starting from a time origin which is determined by performing close-together measurements during a synchronization period in order to identify the pause periods: the time origin is then fixed in the middle of one of said pause periods.

Abstract: A method of optimizing radio communication between a fixed base station having a plurality of antennas and a mobile station by applying, in the base station, processing to all signals S.sub.i (t) received or transmitted via each of the antennas so as to determine corresponding corrected signals S.sub.i (t)=h.sub.i (-t).times.S.sub.i (t), where h.sub.i (-t) is an approximation to the time reversal of the impulse response h.sub.i (t) between antenna and the mobile station.

Abstract: To measure the speed of a body (1) moving relative to the ground (2) by means of a broad-band Doppler radar (3) fixed to the moving body, two incident radar waves are transmitted successively towards the ground at instants that are close together, and the corresponding reflected waves are picked up, the frequency of at least the first incident wave being time-varying, the signals representative of the first incident and reflected waves are multiplied together, a spectrum is determined for the low frequency component of the product of said two signals, the same operations are performed for second incident and reflected waves, then two peaks that correspond with a certain amount of frequency shift in the two spectra are identified, and the speed of the moving body is determined as a function of the frequencies of these two singular points and as a function of the height of the radar relative to the ground.

Abstract: The installation is designed to inform users of a bus network about waiting times for buses at stops in the network. An installation comprises a central station suitable for transmitting radio signals about the real instantaneous positions of the buses, and portable receiver appliances (1) suitable for displaying bus waiting times on screens (4). Each appliance can also serve as a ticket for travel purposes, being provided, for this purpose, with means (10) containing "validity" data (e.g. corresponding to a sum of money or to an expiry date) that can be checked remotely by "ticket-stamper" means (9) and that is also remotely "renewable" from the central station.

Abstract: A system for displaying waiting times for buses (2) approaching various stops (1) of a network. The system comprises means for generating electromagnetic signals (8) whose addresses are based on the buses, fixed receivers (9) of said signals for display purposes at the stops themselves, and preferably also portable appliances (10) also capable of receiving said signals and suitable for displaying the waiting times for buses at any stop of the network in response to interrogation by users bearing said appliances.

Abstract: A portable appliance (1) is provided for informing the users of a bus network about waiting times for buses at various stops of the network. Simple depressions of keys (3, 4, 5) cause appropriate displays to appear on a screen (2) of the appliance, enable a plurality of bus driving distances approaching respective predetermined stops of the network to be stored, and simply pressing on a button (6 or 7) makes it possible to cause any stored driving distance to be selectively displayed on said screen, together with visible information concerning the waiting times for buses at the stop approached by the final driving distance.

Abstract: The installation is intended to inform users of a bus network about waiting times for buses at stops in the network, the installation including a central station suitable for transmitting radio signals relating to the real instantaneous positions of the buses and portable receiver appliances (1) suitable for displaying waiting times on their own screens (3). Each appliance has an appliance identification symbol recorded therein and also (at 11) an expiry date, and it is possible to obtain the desired displays on the screen only if said appliance is used earlier than said date. Provision is made for renewing the appliance remotely for new subscription periods at the end of each subscription.

Abstract: A system for informing users of a bus network about waiting times for buses at stops of the network comprises means (3-6) for generating and transmitting electrical signals representative of the distance (d) between each bus (1) and the "next" stop (2), and means (7) associated with each stop and organized to receive said signals, to select therefrom those signals that concern said stop, and to display at said stop data relating to the waiting times for the "approaching" buses. The system also includes means for generating electrical signals representative of two past real average bus speeds relating to two different periods immediately before the instant at which the signals are generated, and means for using the average speeds in order to determine the waiting times to be displayed.

Abstract: The invention relates to a device for providing the subscriber of a telephone line with information on the telephone calls made on his line. This device, connected to said line, beyond the general connection terminal of the corresponding station, comprises means for detecting and recording durably the numbers called corresponding to the calls successively made in the course of a predetermined period from the station as well as the costs of these calls, and means for displaying on a video screen of the Minitel type, the sequence of these numbers and costs in response to pressing the keys of a key board.