Abstract: A system and device for, and method of, presenting multimedia information. In a client-server context, the invention includes a client that receives units of the multimedia information and presents the information on a presentation device. Each unit of information has an importance value assigned to it, which in an exemplary embodiment is indicative of the unit's importance in relation to the quality of the presentation. The invention includes a mechanism for characterizing the performance capabilities of the system. For example, several conventional statistics may be gathered and analyzed concurrently with the streaming operation and before it begins. The invention includes a mechanism for inferring network conditions from the characterized performance. The server may then stream the units of multimedia information to the client at a streaming rate and adapt the streaming rate of the streaming in response to the importance information and in response to the inferred network conditions.

Abstract: In a data communications system, including an infrastructure arranged to communicate over a data channel with a plurality of data terminals, a method of detecting data decryption errors in a data packet includes receiving an encrypted data packet (213); decrypting the encrypted data packet to provide a decrypted data packet; and comparing a reference value to a portion of the decrypted data packet to determine when a predetermined relationship is satisfied (221).

Abstract: A data terminal, such as a personal digital assistant, personal computer, pager or other such device has a persistent memory (11), a non-persistent memory (12) including a memory item (15 or 16) and an indicator (17 or 18) indicating whether the memory item has been stored in the persistent memory. The data terminal has a power supply (29), a power fail detector (50) for detecting an imminent power failure in the power supply and a switching element (34) coupling the non-persistent memory (12) to the power supply. The switching element causes the power supply to supply power to the non-persistent memory when the indicator indicates that the second memory item has not been stored in the persistent memory and discontinues supply of power to the non-persistent memory when the power fail detector detects an imminent power failure and the indicator indicates that the second memory item has been stored in the persistent memory.

Abstract: An RF power amplifier is provided having means for defining rise and fall envelopes of the RF power, i.e. the key and de-key characteristics. A power amplifier (10), detector (13) and regulator (15 ) form a power control feedback loop. A further regulator (21) is provided having a first input coupled to the output of the power control loop regulator and an output coupled to the input of the power control loop regulator, thereby providing negative feedback to the power control loop regulator. Means are provided, coupled to a second input of the further regulator for providing a rising and falling control signal (Vramp) for control of the power amplifier.

Abstract: A digital fast frequency shift keying (FFSK) demodulator for demodulating an FFSK signal having components at first and second frequencies f0 and f1. The FFSK signal is sampled and the samples are processed in an arrangement which includes a monostable function (50) and a digital notch filter (51) for distinguishing between the components to provide a demodulated output. The digital notch filter (51) is arranged to filter out frequencies which are multiples of the frequencies f0 and f1.