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Installation and setup notes for sidd-0.93, 15th March 2005.------------------------------------------------------------You have unpacked the tgz file and have 3 files:-* README - this one* sidd.c - source code* sidd.conf - a sample configuration file.Installation steps------------------* 1/You will need FFTW3 from www.fftw.org, if not already installed.* 2/Compile the sidd source withgcc -Wall -O4 -ffast-math -DPENTIUM -Wall -o sidd sidd.c -lfftw3 -lmwhich produces an executable sidd in the current directory.* 3/Edit sidd.conf to suit your requirements.* 4/Start sidd in verbose foreground mode with the command./sidd -vf* 5/Examine the log file - it should look something like2005/03/15 20:03:17 logfile /root/sidd.log2005/03/15 20:03:17 los threshold 0.060, timeout 5 seconds2005/03/15 20:03:17 band LB 18200 184002005/03/15 20:03:17 band AN 19480 196802005/03/15 20:03:17 band SK 22050 221502005/03/15 20:03:17 band BG 23300 235002005/03/15 20:03:17 band TV 20190 203402005/03/15 20:03:17 band NV 16300 165002005/03/15 20:03:17 band B1 20800 210002005/03/15 20:03:17 band B2 22650 228502005/03/15 20:03:17 requesting line input gains left=77 right=1002005/03/15 20:03:17 line input gains set to: left=77 right=1002005/03/15 20:03:17 taking data from [/dev/dsp]2005/03/15 20:03:17 requesting rate 480002005/03/15 20:03:17 actual rate set: 48662 samples/sec2005/03/15 20:03:17 soundcard channels: 1 bits: 162005/03/15 20:03:17 resolution: bins=2048 fftwid=4096 df=11.8803712005/03/15 20:03:17 spectrum file: /tmp/sidspec2005/03/15 20:03:17 using SCHED_FIFO priority 12005/03/15 20:03:17 sidd version 0.93: starting work2005/03/15 20:03:17 using output file [./050315.dat]* 6/Now tail the output file (in my example, ./050315.dat). The firstthree columns are the timestamp (seconds from 01/01/1970), peak signallevel (range 0 to 1), and rms signal level (also range 0 to 1).Adjust your mixer gain settings so that the peak hovers around therange 0.1 to 0.5 (the rms will be around 1/2 or 1/3 of the peak, dependingon your level of impulsive noise and sferics).* 7/Plot the spectrum file, in my case /tmp/sidspec. This file is two columns,bin centre frequency in Hz, and relative power. The file is re-written bysidd every 10 seconds or so, depending on your sidd.conf settings. Adjustantennas, receivers, etc to obtain desired signal to noise ratios. Youmay want to reconsider the band settings in sidd.conf at this point too.* 8/Once you're happy with the gain settings, stop sidd and run it again withthe command./sidd -mThis will read and display the applicable mixer gain settings. Now edityour sidd.conf, commenting in the gain commands and putting in your gainsettings. Then, whenever sidd starts, it will setup the mixer with thesesettings. All mixers will have a line input gain control, but only somewill have an overall input gain control and/or a record level control.The -m option will report what you need to put in the config file.* 9/Set your PC clock and activate your favourite time synchronisationsoftware. Make sure it slews the clock rather than stepping the time.* 10/Restart sidd in background with./sidd -vInspect the log file to make sure your mixer settings have been applied.* 11/After a period of time, plot some of the data from the output file.Output file columns 4 onwards correspond to the 'band' commands in theorder they appear in sidd.conf. Each column is a total relative power,so you will need to apply a square root function during plotting if youwant to display relative amplitudes.* 12/After a midnight crossing, make sure sidd has switched to the nextoutput file.Command line options--------------------There are just a few command line options - most controls arein the config file.-v Be a little more verbose with log messages.-f Run in foreground. By default, sidd detaches from the processgroup and terminal and becomes a daemon. In foreground mode,log messages are duplicated to stderr.-m Interrogate the soundcard mixer and report settings, then exit.This option overrides any others.Miscellaneous notes-------------------*sidd will set the soundcard to the nearest available sample rate to thatspecified in sidd.conf*Make sure you have enough disk space. The example sidd.conf with 8 bandsgenerates files of about 100Mbytes per day, which compress down to about30Mbytes. Arrange scripts for plotting. Arrange scripts for compressingand archiving files that are a few days old.*You can specify an ordinary file or a pipe as the input 'device' insteadof /dev/dsp. In this case, you must set the sample rate in sidd.confto whatever the actual sample rate is. sidd is looking for unsigned bytesin 8 bit mode, or signed words in 16 bit mode.*Once sidd has started up and set the mixer gains, it no longer takes anynotice of the mixer. Therefore once sidd is running, a rogue user canmess things up by twiddling the mixer settings with Xmixer or some otherutility. Kill off any mixer control panels to avoid the risk of any upset.*If your PC is set to autoboot after a power outage, you might want to puta startup command for sidd into /etc/rc.d/rc.local or similar - but makesure the RTC setting commands are done first.Revisions---------v0.9: Original.v0.91: Fixes a header file problem with some gcc.No longer produces a static binary.v0.93: Another bug fixed.Added control of mixer input and gains.Added stereo mode to make a 2 channel monitor.