Kristen Rohlfs & T. L. Wilson 
Tools of Radio Astronomy [PDF ebook] 

This textbook addresses students and practitioners. It attempts to give an outline of the methods and tools of radio astronomy needed by the astronomer who wants to relate the message from interstellar space to physical processes. It gives a unified treatment of the entire field of radioastronomy from the centimetre to the sub-millimetre wavelength range, discussing both single telescopes and interferometric devices. It describes the basic physical principles and gives a reasonably complete outline of the instruments and methods of measurements and analysis, including both continuum radiation and spectral lines. This second edition has been largely rewritten and expanded. It includes the most recent developments in astronomy.