Digital signal

About: Digital signal is a research topic. Over the lifetime, 44213 publications have been published within this topic receiving 345279 citations.

Multi-channel digital transceiver and method

Abstract: A multi-channel digital transceiver (400) receives uplink radio frequency signals and converts these signals to digital intermediate frequency signals. Digital signal processing, including a digital converter module (426), is employed to select digital intermediate frequency signals received at a plurality of antennas (412) and to convert these signals to baseband signals. The baseband signals are processed to recover a communication channel therefrom. Downlink baseband signals are also processed and digital signal processing within the digital converter module (426) up converters and modulates the downlink baseband signals to digital intermediate frequency signals. The digital intermediate frequency signals are converted to analog radio frequency signals, amplified and radiated from transmit antennas (420).

An Implementation of Key-Based Digital Signal Steganography

Abstract: A real-life requirement motivated this case study of secure covert communication. An independently researched process is described in detail with an emphasis on implementation issues regarding digital images. A scheme using stego keys to create pseudo-random sample sequences is developed. Issues relating to using digital signals for steganography are explored. The terms modified remainder and unmodified remainder are defined. Possible attacks are considered in detail from passive wardens and methods of defeating such attacks are suggested. Software implementing the new ideas is introduced, which has been successfully developed, deployed and used for several years without detection.

The maximum sampling rate of digital filters under hardware speed constraints

Abstract: This paper presents a framework for Fiding efficient multiprocessor realizations of digital filters. Based on simple graph-theoretic concepts, a method is derived for determining the minimal sampling period of a given digital filter structure when the speed of arithmetic operations is given but the number of processing units Is unlimited. It Is shown how realistic hardware implementations can be found and evaluated by using the timing diagram of this maximal rate realization as a starting point. The minimal sampling periods of several common digital filter structures are given in terms of addition and multiplication times.

Integrated television services system.

Abstract: A system is disclosed for delivering audio and/or video signals to users in connection with the provision of interactive television services. Various sources of such signals are connected to a digital network, such as a packet network. Also connected to such network are control and application processors and interfaces to distribution arrangements such as cable television systems and telephone subscriber loops. Each user has a signal converter for receiving a digital signal from the distribution arrangement, converting such signal for viewing on a conventional television receiver and transmitting control packets to other elements of the system. The signal sources can include a data cache for storing recorded video and audio materials, a broadcast source for receiving broadcast signals, apparatus for composing multimedia signals from multiple sources and apparatus for running games. The various elements of the system can be situated at different geographical locations and operated by the control and/or application processors under software control to provide a variety of interactive television services.

Integrated radio satellite response system and method

Abstract: A radio response system including a broadcast station, a satellite relay, a processing center, and a plurality of user terminals. Each user terminal has a broadcast receiver, a communications interface device, a controller and a data transmitter. The broadcast station broadcasts a program signal. The broadcast receiver receives the program signal. The communications interface device communicates the program signal to a user. The controller generates a user-data signal from identification information transmitted in connection with the program signal and/or timing, location and frequency information needed for identifying the program signal, and a user-input signal generated in response to the program signal. The data transmitter transmits the user-data signal at a carrier frequency as a transmitted-data signal. The satellite relays the user-data signal to the processing center.