The invention relates to a transmission blocker for mobile telephones as well a method for preventing transmission activities of mobile telephones in the vicinity of safety-relevant electronic devices, comprising a device for transmitting radio signals as interference signals in the frequency range of the relevant mobile radio network in such fashion that synchronization of the mobile telephone with a radio station and/or decoding of the information in the signaling channel and/or recognition of...

A scrambling system includes a scrambling apparatus and a descrambling apparatus for scrambling and descrambling digital audio codes having plural sub-band units. Each sub-band unit includes at least a scale factor and a quantized sample data which is quantized after scaling with the scale factor. In the scrambling apparatus, a sample period during which the quantized sample data is present is detected, and only the quantized sample data is scrambled at the sample period. In particular, the quan...

In a mobile communication system of the WACS type, frame formats are unified for DSL, HDSL, and DS1 channels. In addition, each novel base station (25) comprises a radio frame number processor for adding, to upward encrypted information data directed from mobile stations (27) towards a base control station (21), a radio frame number which is used in downward encrypted information data transmitted from the base control station to one or more of the mobile stations and may not necessarily be used ...

A messaging system in which a sender is able to receive certification of receipt of messages sent to a receiver that ensures that only the desired recipient gains access to the messages. Also, the messaging system sends between a sender and a receiver both encrypted communications and decryption information used to decipher the encrypted communications.

Techniques for playing and distributing MIDI tracks in the context of a non-real-time network such as the Internet. One of the techniques makes it possible to begin playing a multi-track MIDI file that is being received over the Internet before the entire file has been received. Others of the techniques permit playing of MIDI tracks that are generated in real time and then distributed via the Internet. The techniques ensure that expected network delays will not cause underflow in the MIDI buffer...

A card-enabled processing system comprises a security module for securely exchanging data with cards, such as smart cards, and an application module for processing data from the smart cards. The security module encrypts and decrypts data using keys, which are securely stored in a secure memory. The security module also validates the cards before processing by the application module occurs and assists the card in validating the system. The application module provides a common platform in which di...

A lightweight (i.e., less than 50 kg) optical jammer system for use with a satellite in earth orbit. The jammer system is mounted on the satellite and produces an obfuscating programmable signature of concentrated sunlight which is modulated and directed to earth. A potential enemy observer on earth is thereby prevented from ascertaining the general mission of the satellite, because the known reflected sunlight signature of the satellite is masked.

Channel selection in a frequency hopping radio set is controlled by a pseudo-random number generator, the pseudo-random number being used to address an N bit memory (3) which is used to identify each of n available channels from N equipped channels. When a preselected number of the n channels have been identified by the psuedo-random number generator a latch (4) is enabled to store the channel number for selection purposes. Various scrambling methods are employed so that the channels on which on...

In order to achieve a higher resistance to interference with respect to alien sources of deliberate interference in the use of communication connections via short waves, certain cooperative measures are proposed which include that the stations are equipped with highly-constant quartz crystal clocks and the bursts of information to be transmitted are accompanied by a time signal with the aid of which it is possible to correct any time tolerances between the stations. With an acknowledgment signal...

A receiver of digitally encoded voice signals that may be encrypted according to a plurality of keep subjects a received signal to decryption according to each of the keys. Decrypted signals are tested for the presence of modulation, and the signal, if any, that is decrypted is recovered for use. If it is desired, a visual indication may tell a user which key is being used to decrypt the signal.