noise at high freqencies - (an important factor)

6-34 — elektor june 1980 noise at high frequencies Noise in UHF/VHF receivers can be determined by using extensive and expensive test equipment. However, tests with a noise generator can give usable results at a much lower cost. Such a noise generator can, of course, be constructed by the amateur. 1 (an important factor) What is noise? Noise is caused by highly complicated physical and thermodynamic processes. Briefly, it is the random movement of electrical charge carriers. Noise increases with rise in temperature: at absolute zero (-273°C = 0 K) noise is zero, for at this temperature all movement is frozen. This is why during certain critical processes, cryogenic techniques are used to attenuate the noise factor to obtain a certain signal-to-noise ratio at the output. How to determine the noise factor The noise factor in receivers can be calculated in two different ways, either from a sensitivity or from a noise measurement. In order to test sensitivity a signal generator is ...