![]() ![]() A tracking generator usually does not include very expensive components. To avoid the drawbacks of noise measurements, almost all manufacturers offer tracking generators that produce a coherent sinusoidal signal on the receiving frequency of the spectrum analyzer, either built-in or as separate units. Finally, noise measurements always require some averaging (video filtering) due to the random nature of noise signals. Further, the dynamic range of noise measurements is quite limited, since the device under test and the input of the spectrum analyzer are both loaded with much larger power levels than are actually being measured. Since the noise figure of typical spectrum analyzers is rather high, in the range around 15-20dB, the required ENR (excess noise ratio) of the noise source is very high. The simplest tracking generator is a wide-band noise source, since part of the noise power always falls in the instantaneous receiving bandwidth of the spectrum analyzer. With an additional directional coupler or bridge, reflection measurements can be performed in the whole frequency range covered by the spectrum analyzer. A tracking generator therefore allows testing many passive and active RF circuits that do not produce any RF signals on their own, like filters, amplifiers etc. A tracking generator produces a RF signal on the exact frequency where the spectrum analyzer is receiving at the same time. A basic and very useful addition to a spectrum analyzer is a tracking generator. ![]()
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