Crystal oscillators have been in use now for well over SO years-one of the first was built by W. G. Cady in 1921. Today, millions of them are made every year, covering a range of frequencies from a few Kilohertz to several hundred Mega hertz and a range of stabilities from a fraction of one percent to a few parts in ten to the thirteenth, with most of them, by far, still in the range of several tens of parts per million.Their major application has long been the stabilization of fre quencies in transmitters and receivers, and indeed, the utilization of the frequency spectrum would be in utter chaos, and the communication systems as we know them today unthinkable, 'without crystal oscillators. With the need to accommodate ever increasing numbers of users in a limited spectrum space, this traditional application will continue to grow for the fore seeable future, and ever tighter tolerances will have to be met by an ever larger percentage of these devices."

An engineer's introduction to concepts, algorithms, and advancements in Digital Signal Processing. This lucidly written resource makes extensive use of real-world examples as it covers all the important design and engineering references.

A great deal of modern communications equipment is being converted from analog to digital technology. This timely book explains many of the important concepts related to digital signal processing in easy-to-understand discussions of communications techniques, data transmission, filters, and hardware. Readers are given practical information on how to apply theory and algorithms to the design of radio receivers and transmitters. Among the areas discussed are analog to digital conversion - with emphasis on noise and distortion performance; manipulation of complex signals - positive and negative frequencies, plus Hilbert transformers; digital filters - guidelines for performance in communications, plus decimation and interpolation; hardware - multiplier accumulators, fast Fourier transform processors, digital signal processors, data flow techniques in equipment, and hardware simulation and testing; and speech processing - linear predictive coding (LPC), code excited linear predictive coding (CELP), and how to digitize speech at low data rates. Development of algorithms for oscillators, detectors, modulators, automatic gain control circuits, and other devices is clearly explained. Specific algorithms are provided for AM modulation, frequency modulation, FM detection, threshold extension, audio compression, automatic gain control, and squelch circuitry. Explanations of basic concepts of digital signal processing and data transmission are accompanied by reviews of signal representations, sampling, convolution, and z-transforms. Extensive real-world examples contribute to expertise in many facets of incorporating digital technology into devices. This hands-on treatment of DSP will helpcommunications engineers upgrade their skills in digital signal processing and make a smooth transition into the design of more advanced systems. It also meets the needs of students who want to bolster their knowledge in communications.