NAME: THM_LSP_GET_SPEC (PROCEDURE) PURPOSE: Get the power spectrum density (PSD) of a given tplot variable. CALLING SEQUENCE: thm_lsp_get_spec, tvar, units = units, prefix = prefix, fftlen = fftlen, $ yrange = yrange ARGUMENTS: tvar: (INPUT, REQUIRED) The name of a tplot variable to calculate the PSD from. KEYWORDS: units: (INPUT, OPTIONAL) A string of the units of the data in the tvar. By default, it is obtained from dlim.data_att.units, or 'unknown' if dlim.data_att.units is not available. prefix: (INPUT, OPTIONAL) The prefix for tplot variables that contain the resulting PSD. By default, prefix = tvar. fftlen: (INPUT, OPTIONAL) The number of data points to FFT. By default, fftlen = 512. yrange: (INPUT, OPTIONAL) The yrange for the spectra. By default, yrange = [1, Nyquist] in units of Hz. ufactor: (INPUT, OPTIONAL) A factor to convert units from one to another. instr_resp: (INPUT, OPTIONAL) The instrument response as a function of frequency. The number of elements of instr_resp should be the same as (fftlen/2 + 1). By default, instr_resp = 1. /checkenergy: (INPUT, OPTIONAL) If set, the ratios of time-domain energy to freq-domain energy are stored into tplot variables. By default, no such output is generated. /phase: If set, phase will be calculated and saved into tplots. /ft : If set, the FFT of the input data will be saved. EXAMPLES: See thm_crib_lsp_get_spec.pro which is typically located under TDAS_DIR/idl/themis/examples. HISTORY: 2010-03-07: Created by Jianbao Tao (JBT), CU/LASP. 2012-07-26: JBT, SSL, UC Berkeley. 1. Removed the spectral averaging. 2. Added keywords *phase* and *ft* to output phase and FFT data. VERSION: $LastChangedBy: jianbao_tao $ $LastChangedDate: 2012-07-27 12:29:50 -0700 (Fri, 27 Jul 2012) $ $LastChangedRevision: 10753 $ $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/projects/themis/spacecraft/fields/LASP/thm_lsp_get_spec.pro $