SPECTRUM ANALYZER; Types of measurements

Types of measurements 
Common spectrum analyzer measurements include frequency, power,modulation, distortion, and noise. Understanding the spectral content of a signal is important, especially in systems with limited bandwidth. Transmitted power is another k y measurement. Too little power may mean the signal cannot reach its intended destination. Too much pow r may drain batteries
rapidly, create distortion, and cause excessiv ly high operating t mperatures.

Measuring the quality of the modulation is important for making sure a system is working properly and that the information is being correctly transmitted by the system. Tests such as modulation degree, sideband amplitude, modulation quality, and occupied bandwidth are examples of common analog modulation measurements. Digital modulation metrics include error vector magnitude ( EVM) , IQ imbalance, phase error v rsus time, and a variety of other measurements. For more information on these measurements, see Application Note 150-15, Vector Signal Analysis Basics .

In communications, measuring distortion is critical for both the receiver and transmitter. Excessiv harmonic distortion at the output of a transmitter can int rfere with other communication bands. The pre-amplification stages in a receiv r must be free of intermodulation distortion to prevent signal crosstalk. An example is the int rmodulation of cable TV carriers as th y mov down the trunk of the distribution system and distort other channels on the same cable. Common distortion measurements include int rmodulation,
harmonics, and spurious emissions.

Noise is often the signal you want to measure. Any active circuit or device will generate excess noise. Tests such as noise figure and signal-to-noise ratio ( SNR) are important for characterizing the performance of a d vice and its contribution to overall system performance.