A watchdog is a device used to protect a system from specific software or hardware failures that may cause the system to stop responding. The application is first registered with the watchdog device. Once the watchdog is running on your system the application must periodically send information to the watchdog device. If the device doesn’t receive this signal within the set period of time it would execute the proper keystrokes to reboot the machine or restart the application.
Watchdog services are also available for Internet Web sites. In these instances the watchdog may be set to monitor your own Web site by attempting to access it from several different city or country locations at regular intervals. You could then view an online report of the connectivity or have the watchdog system e-mail you should it become inaccessible.
Some Web sites also offer readers a watchdog service where they receive instant e-mail notification when the Web site offering the service has been updated.
- digital watermark
Also referred to as simply watermarking, a pattern of bits inserted into a digital image, audio or video file that identifies the file’s copyright information (author, rights, etc.). The name comes from the faintly visible watermarks imprinted on stationery that identify the manufacturer of the stationery. The purpose of digital watermarks is to provide copyright […]
A commonly used term in the telecommunications industry. Waveform is a graphical representation of a signal as a plot of amplitude versus time, i.e., the shape of a wave.
- wave table synthesis
A technique for generating sounds from digital signals. Wave table synthesis stores digital samples of sound from various instruments, which can then be combined, edited, and enhanced to reproduce sound defined by a digital input signal. Wave table synthesis reproduces the sound of musical instruments better than Frequency Modulation (FM) synthesis. The MIDI standard supports […]
A circular, elliptical or rectangular metal tube or pipe through which electromagnetic waves are propagated in microwave and RF communications. The wave passing through the medium is forced to follow the path determined by the physical structure of the guide.
A mathematical function used in compressing images. Images compressed using wavelets are smaller than JPEG images and can be transferred and downloaded at quicker speeds. Wavelet technology can compress color images from 20:1 to 300:1, grayscale images from 10:1 to 50:1.