what is periodogram
Periodogram is the spectrum of a set of time signal usually obtained by fast Fourier transform (FFT). It usually shows frequency as x-axis, and magnit... This page may be out of date.
A seismogram is a visual record that is created by a seismograph. A seismograph is a piece of equipment that records earthquake movements. These two items go hand in hand and are essential for the study of earthquakes. Without a seismograph, there would be no seismogram. A seismograph detects movement in the Earth's crust, translating that movement through its inner workings to move a recording device, often a needle, that makes markings on what becomes the seismogram.