Abstract: Techniques for simultaneously and efficiently eliminating echo and noise mixed in voice are disclosed. According to one aspect of the present invention, an adaptive filter system for eliminating noises and echo mixed in voice signal comprises a first signal adaptive filter, a first subtractor, a second adaptive filter and a second subtractor. The first signal adaptive filter estimates the noise mixed in the voice signal according to a reference noise. The first subtractor subtracts the noise estimated by the first adaptive filter from the voice signal to obtain a voice signal without the mixed noise. The second adaptive filter estimates the echo mixed in the voice signal according to a remote voice signal. The second subtractor subtracts the echo estimated by the second adaptive filter from the voice signal without mixed noise to obtain a clean voice signal.

Abstract: Techniques for storing and reading data on/from a hard disk are disclosed. According to one aspect of the present invention, a hard disk is provided with a parameter storage block for storing a number of parameters. One of the parameters is a last physical address the hard disk was accessed. The last physical address is used as a reference to read data segments onto the hard disk. Each of the data segments is a compressed version of a portion of data to be stored in the hard disk. A portion of the data is allocated in accordance with a predefined time period. Accordingly, the compressed data portion also includes a header including information about the compressed data portion. The information includes at least a compression scheme used as well as the time about the data portion. Based on how the data is stored, a corresponding reading method is also provided.

Abstract: Techniques for transmitting data between devices based on two-dimensional symbols are disclosed, where the devices are generally not equipped with the traditional networking capabilities, or at least these traditional networking capabilities are not used for the data communication. According to one aspect of the techniques, two devices communicate with each other by displaying one or more two-dimensional symbols. Data is encoded into one or more symbols that are displayed on one of the devices. Images of the symbols are taken by another one of the devices to receive the data. These images are sequentially processed and decoded so that the data is now received. To accommodate various environments, the system is configured to adjust parameters pertaining to the symbols to achieve an optimum transmission rate.