.\@(#)bw_relp.man 2.3 06/30/00 .TH PSD 4.1 "30 June 2000" .SH NAME psd \- Background Noise Power Spectral Density Estimation .SH SYNOPSIS .B psd \fIseed_data_volume\fR .br .SH DESCRIPTION .B psd is a background noise acceleration Power Spectral Density (PSD) estimation algorithm designed specifically to extract all necessary information and data for calculating the PSD estimates from a SEED data volume. It is an exportable version of the acceleration PSD algorithm that has been in routine use at the Berkeley Seismological Laboratory (BSL) for approximately the past decade. The .B psd algorithm is a script that calls a series of three algorithms that extract the requisite station coordinate, sensor transfer function, and data files. The essential components of the .B psd script are: rdseed -s -f $sdv > sdv_temp which uses "rdseed" to retrieve all station and channel header information from the SEED data volume "$sdv" and write it to a temporary file "sdv_temp"; grep B050F sdv_temp | sdv_coord > instr.sdv.coord which does a pattern grep on the station coordinate entries in the sdv_temp file and uses the supplied "sdv_coord" algorithm to generate "instr.sdv.coord" containing the station coordinate information; grep B05 sdv_temp | sdv_resp > instr.sdv.resp which does a pattern grep on the station sensor entries in the sdv_temp file and uses the supplied "sdv_resp" algorithm to generate "instr.sdv.resp" containing the sensor transfer functions and related information; rdseed -d -o 1 -f $sdv which uses "rdseed" to dump the data records in SAC binary format; and finally a foreach loop: .nf foreach sbdf (`ls | grep SAC`) sdv_psdest $sbdf set x = $status if ( $x == 0 ) then \\rm $sbdf echo File $sbdf processed. else set np = `sachdr $sbdf | grep npts | awk '{ print $3 }'` echo File $sbdf contained only $np samples. endif end .fi to process each of the SAC binary data files, that contain at least 65536 data samples without any time gaps, and calculate the acceleration PSD estimate using the "sdv_psdest" algorithm. Note that the SAC algorithm \fIsachdr\fR, supplied in the PASSCAL Software Suite, is called in .B psd to determine the number of samples in the file. The \fIsdv_psdest\fR algorithm was intentionally designed to operated in an automated fashion without any optional command line arguments. This minimizes the possibility of inappropriate use of the algorithm that could produce biased PSD estimates. The original in-house version of the \fIsdv_psdest\fR algorithm used at the Berkeley Seismological Laboratory was written in Fortran 77. The \fIf2c\fR translator was used to convert the Fortran 77 source code to C source files. The Fortran 77 source code was cleaned up and necessary subrouutines, not included in the \fIf2c\fR libraries, were added to expedite the conversion process. The \fIsdv_coord\fR and \fIsdv_resp\fR algorithms were converted in a similar fashion. The only \fIf2c\fR option used in the conversion was "-c" which causes the original Fortran 77 source code to be embedded as comments in the C source files. The \fIsdv_psdest\fR algorithm uses a statistical approach to robustly estimate the background noise PSD. The input time series is parsed into eight (possibly overlapping) time series and each of the resulting time series are appropriately windowed prior to calculating their PSD estimates. For short time series, less than 1.5 hours in length, the time series are detrended and sine tapered while for longer time series the dominant semi-diurnal gravitational tide signal is also removed to avoid biasing the long-period PSD estimates. A caveat: since the transfer function representation in the SEED data volumes for typical broadband seismometers does not include the static component of the response, the background noise PSD estimates for periods longer than an approximately an hour will be biased high and hence they will be unreliable. .SH OPTIONS The only command line option (required) for .B psd is the name of the SEED data volume which is to be processed: .TP \fIseed_data_file\fR The SEED data volume provides the algorithms in .B psd with all the requisite information for calculating the background noise PSD esrimates. .SH OUTPUT Besides the information that is printed to the screen, .B psd outputs a station coordinate file \fIinstr.sdv.coord\fR, a sensor transfer function file \fIinstr.sdv.resp\fR, and a file with a ".psd" suffix for each data stream, that meets the minimum requirements of the PSD estimation algorithm, extracted from the SEED data volume. .TP EXAMPLE FILE - \fIinstr.sdv.coord\fR .TP Invoking .B psd \fIybh_sdv\fR, as shown in the example subdirectory, will extract the requisite data from the \fIybh_sdv\fR SEED data volume and genrate an \fIinstr.sdv.coord\fR file containing: .nf YBH BK 41.7320400 -122.7103880 1059.70 1996.296.0000 3000.001.0000 Yreka Blue Horn .fi where the columns are: station, network, latitude, longitude, elevation, start date, end date, and location. .TP EXAMPLE FILE - \fIinstr.sdv.resp\fR .TP Invoking .B psd \fIybh_sdv\fR will also extract the requisite data from the ybh_sdv SEED data volume and genrate an \fIinstr.sdv.resp\fR file containing the pole/zero/scaling constant representation of the transfer function for each sensor for which there is data in the SEED data volume: .nf YBH BK XX LHE 1996.296.0000 3000.001.0000 41.7320400 -122.7103880 1059.70 60.40 90.00 .00 M/S .986864E+12 2 4 .000000E+00 .000000E+00 .000000E+00 .000000E+00 -.123412E-01 .123415E-01 -.123412E-01 -.123415E-01 -.195878E+02 .245617E+02 -.195878E+02 -.245617E+02 YBH BK XX LHN 1996.296.0000 3000.001.0000 41.7320400 -122.7103880 1059.70 60.40 .00 .00 M/S .911518E+12 2 4 .000000E+00 .000000E+00 .000000E+00 .000000E+00 -.123412E-01 .123415E-01 -.123412E-01 -.123415E-01 -.195878E+02 .245617E+02 -.195878E+02 -.245617E+02 YBH BK XX LHZ 1996.296.0000 3000.001.0000 41.7320400 -122.7103880 1059.70 60.40 .00 -90.00 M/S .962459E+12 2 4 .000000E+00 .000000E+00 .000000E+00 .000000E+00 -.123412E-01 .123415E-01 -.123412E-01 -.123415E-01 -.195878E+02 .245617E+02 -.195878E+02 -.245617E+02 .fi where, for each component: the first line gives the station code, network, location, data stream, start date, and end date; the second line gives the sensor latitude, longitude, elevation, and depth of burial; the third line gives the component azimuth, dip angle, and flat passband units; the fourth line gives the scaling constant, the number of complex zeros, and the number of complex poles; and the fifth through nth lines gives the complex zero values (no more than two complex numbers per line) followed by the complex pole values (also no more than two complex numbers per line). The sequence is repeated for each unique station code-network-location-component in the SEED data volume. .TP EXAMPLE PSD OUTPUT FILE - \fIYBH.BK.LHZ.XX.D.2000.178.0000.psd\fR .TP Invoking .B psd \fIybh_sdv\fR will also generate a PSD results file for each unique station code-network-location-component in the SEED data volume. The file naming follows the SEED convention and inserts an "XX" in the place of the location if the location is not specified. A ".psd" is appended to the SEED file name. An example of a PSD results file, YBH.BK.LHZ.XX.D.2000.178.0000.psd in the example subdirectory, is: .nf Acceleration Power Spectral Density Estimate Processing Date Wed Jul 19 14:35:57 PDT 2000 Network BK Station YBH Channel LHZ Location XX Number of points 86400 Sample rate (sps) 1.0000 Start Date/Time 2000 178 0 0 0 823 Length of FFT 16384 PSDs averaged 8 Points shifted 9919 Min & Max PSD No. 7 1 Min & Max std err 111.102661 148.638733 (in counts) PSD in dB referenced to 1 (m/s**2)**2/Hz Period PSD LB PSD min PSD med PSD max PSD UB (sec) (db) (db) (db) (db) (db) 1638.400 -168.38834 -167.02596 -165.35931 -166.20975 -161.43890 1462.203 -169.37077 -168.00839 -166.34177 -167.19218 -162.42134 1304.956 -170.34985 -168.98747 -167.32083 -168.17126 -163.40042 1164.619 -170.59071 -170.59071 -168.98082 -169.12317 -165.02768 1039.374 -171.47586 -171.47586 -169.56149 -170.68668 -167.32243 927.5980 -174.03415 -172.54893 -170.42093 -174.03415 -169.76917 827.8426 -172.76053 -170.93161 -171.51901 -172.76053 -170.92393 738.8151 -173.71457 -172.94249 -172.85071 -173.54900 -170.95023 659.3618 -174.41260 -173.87346 -173.72192 -172.83858 -172.83858 588.4529 -176.10869 -175.66737 -174.81923 -174.46793 -174.29036 525.1698 -177.34253 -177.34253 -176.36523 -174.62498 -174.62498 468.6922 -178.88013 -178.49683 -177.37491 -175.48476 -175.48476 418.2883 -179.96187 -179.34848 -178.80994 -176.54405 -176.54405 373.3049 -181.44315 -180.12718 -179.49158 -177.71735 -177.71735 333.1591 -182.72328 -180.18291 -180.31950 -178.60551 -178.60551 297.3306 -182.91478 -181.82552 -181.35762 -179.35602 -179.24556 265.3552 -183.00632 -181.94067 -181.94708 -180.65727 -180.28470 236.8185 -184.01825 -182.41615 -182.43581 -180.96719 -180.96719 211.3507 -183.98384 -182.60445 -182.67880 -181.35233 -180.98056 188.6217 -184.23106 -183.72298 -182.76050 -181.58556 -181.33028 168.3370 -184.32166 -183.54443 -182.89197 -181.84503 -181.84503 150.2338 -184.49385 -183.92537 -183.20618 -181.09390 -181.09390 134.0774 -184.44151 -184.44151 -183.52002 -180.95381 -180.95381 119.6585 -185.02162 -185.02162 -183.88831 -180.98755 -180.98755 106.7902 -185.31282 -185.31282 -184.10703 -179.60600 -179.60600 95.30582 -185.52632 -185.52632 -185.07741 -177.81160 -177.81160 85.05650 -186.34065 -186.34065 -185.56161 -176.58374 -176.58374 75.90942 -186.91449 -186.84898 -186.29384 -174.79771 -174.79771 67.74601 -187.70616 -187.49275 -186.73956 -172.36865 -172.36865 60.46051 -187.83774 -187.72551 -186.31906 -170.68539 -170.68539 53.95851 -187.91620 -187.76353 -185.26706 -169.37483 -169.37483 48.15574 -187.05426 -187.05426 -184.01324 -166.92999 -166.92999 42.97701 -186.24025 -186.24025 -182.00900 -163.91563 -163.91563 38.35520 -184.82481 -184.82481 -179.42068 -160.63492 -160.63492 34.23043 -182.48813 -182.48813 -176.48869 -157.28188 -157.28188 30.54925 -179.42862 -179.32231 -172.40747 -153.90202 -153.90202 27.26394 -176.59674 -176.50986 -168.71765 -151.26773 -151.26773 24.33194 -172.78209 -172.78209 -165.13660 -148.78032 -148.78032 21.71525 -168.58115 -168.41124 -162.72318 -148.36920 -148.36920 19.37996 -165.17551 -165.10526 -161.18213 -148.45227 -148.45227 17.29581 -162.85893 -162.85893 -160.04968 -147.59035 -147.59035 15.43580 -160.78381 -160.78381 -159.23019 -146.28749 -146.28749 13.77581 -160.08301 -159.56273 -159.13156 -145.16370 -145.16370 12.29434 -158.74533 -158.01352 -157.71356 -143.68265 -143.68265 10.97219 -156.61784 -155.44029 -155.16611 -141.71407 -141.71407 9.792231 -153.63385 -152.39557 -152.20276 -140.31293 -140.31293 8.739160 -149.49716 -148.58427 -148.33472 -139.13786 -139.13786 7.799337 -144.63336 -144.53076 -144.49423 -137.72183 -137.72183 6.960586 -141.74251 -141.65910 -141.22354 -135.97588 -135.97588 6.212034 -139.81697 -139.75848 -139.10432 -134.19365 -134.19365 5.543983 -137.49036 -137.49036 -137.00966 -132.71323 -132.71323 4.947774 -134.69475 -134.69475 -134.33992 -131.34843 -131.34843 4.415684 -132.76901 -132.68925 -132.51857 -130.15715 -130.15715 3.940814 -131.96111 -131.67375 -131.53299 -129.64851 -129.64851 3.517014 -130.97412 -130.68677 -130.54599 -128.66153 -128.66153 3.138789 -129.98746 -129.70010 -129.55933 -127.67486 -127.67486 .fi where: the first 17 lines contain header information and the 18th through last lines give the acceleraion PSD estimates where the first column gives the period of PSD estimate in seconds and the remaining columns give the lower bound (LB), minimum (min), median (med), maximum (max), and upper bound (UB) of the background noise acceleration PSD estimate. The minimum (min) and maximum (max) columns refer to the estimates which have the minimum and maximum sums over all periods (the time series corresponding to each is given in the 13th header line) while the lower bound (LB) and upper bound (UB) columns give the lowest and highest estimate for each period. The PSD estimate in the "PSD min" column is the most robust estimate of the background noise PSD. .SH AUTHOR Bob Uhrhammer, UC Berkeley Seismological Laboratory, Email: bob@seismo.berkeley.edu .SH BUGS Report any bugs, problems or suggestions to the author.