Abstract: Inside a range of action defined by a station, the station is able to generate therein an enquiry message followed by a silence zone. The station then selectively analyzes the respective contents of a plurality of disjoint time intervals from this silence zone. In the event of obtaining in one of these time intervals, chosen randomly by a single portable object, a content identified as a specified response message associated with this portable object, the station generates a selection message intended for this portable object, which, on reception of this selection message, generates in its turn an acknowledgement message. There follows provision for a phase of transactional communication between the selected portable object and the station.

Abstract: A video path receives the signal to be processed and a reference path receives a reference voltage, with both paths subjecting their respective signals to logarithmic amplification having the same characteristics. These two paths are combined in a summing circuit giving gains respectively of gamma and of one minus gamma. The output from the summing circuit is applied to an exponential amplifier which is followed by a buffer to provide the corrected output signal. By an appropriate adjustment of resistances in the summing stage and also by means of switching, it is possible to perform gamma correction over the range about 0.2 to about 5, and it is possible to perform such correction on very wideband analog signals.

Abstract: In a telephone installation, telephone rental data is loaded remotely into an independent station in the following manner.In response to a request for a call coming from the independent station and in the presence of a load request signal, a control means searches all the telephone rental data relative to the independent station as well as that indicating an order for the remote loading. A coding means codes with the help of a special key data which is secret. A processing means authorises the transmission of non-secret pubic telephone rental data as well as secret data thus encoded to the said independant station according to the order for the remote loading.At the independent station a decoding means deciphers the coded secret telephone rental data thus received with the help of the special key and a processing means stores the non-secret public telephone rental data thus transmitted and secret data thus decoded in a memory of the independent station.