Also referred to as quota control, it is a method of selecting subjects for a study. The subjects are already chosen for specific characteristics such as age, sex, education, etc.The quota sampling assures the proper proportion of these traits in the group.lso referred to as quota control, it is a method of selecting subjects for a study. The subjects are already chosen for specific characteristics such as age, sex, education, etc.
In contrast, a broadband signal is a signal which does not occupy the lowest range, but instead a higher range, 1MHz to 3MHz, for example. A wire may have only one baseband signal, but it may hold any number of broadband signals, because they can occur anywhere in the spectrum.
These new spectral components are called sidebands. Amplitude Modulated Signal. Amplitude modulation occurs often in vibration signals generated by rotating machines. It is usually recognized by the presence of sidebands in the vibration spectrum. The most common modulating frequency is the turning speed, or 1X vibration component, and common modulated frequencies are gear mesh and bearing tones.