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kaklik |
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Installation and setup notes for sidd-0.93, 15th March 2005.
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------------------------------------------------------------
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You have unpacked the tgz file and have 3 files:-
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* README - this one
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* sidd.c - source code
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* sidd.conf - a sample configuration file.
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Installation steps
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------------------
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* 1/
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You will need FFTW3 from www.fftw.org, if not already installed.
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* 2/
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Compile the sidd source with
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gcc -Wall -O4 -ffast-math -DPENTIUM -Wall -o sidd sidd.c -lfftw3 -lm
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which produces an executable sidd in the current directory.
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* 3/
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Edit sidd.conf to suit your requirements.
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* 4/
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Start sidd in verbose foreground mode with the command
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./sidd -vf
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* 5/
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Examine the log file - it should look something like
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2005/03/15 20:03:17 logfile /root/sidd.log
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2005/03/15 20:03:17 los threshold 0.060, timeout 5 seconds
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2005/03/15 20:03:17 band LB 18200 18400
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2005/03/15 20:03:17 band AN 19480 19680
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2005/03/15 20:03:17 band SK 22050 22150
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2005/03/15 20:03:17 band BG 23300 23500
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2005/03/15 20:03:17 band TV 20190 20340
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2005/03/15 20:03:17 band NV 16300 16500
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2005/03/15 20:03:17 band B1 20800 21000
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2005/03/15 20:03:17 band B2 22650 22850
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2005/03/15 20:03:17 requesting line input gains left=77 right=100
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2005/03/15 20:03:17 line input gains set to: left=77 right=100
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2005/03/15 20:03:17 taking data from [/dev/dsp]
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2005/03/15 20:03:17 requesting rate 48000
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2005/03/15 20:03:17 actual rate set: 48662 samples/sec
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2005/03/15 20:03:17 soundcard channels: 1 bits: 16
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2005/03/15 20:03:17 resolution: bins=2048 fftwid=4096 df=11.880371
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2005/03/15 20:03:17 spectrum file: /tmp/sidspec
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2005/03/15 20:03:17 using SCHED_FIFO priority 1
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2005/03/15 20:03:17 sidd version 0.93: starting work
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2005/03/15 20:03:17 using output file [./050315.dat]
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* 6/
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Now tail the output file (in my example, ./050315.dat). The first
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three columns are the timestamp (seconds from 01/01/1970), peak signal
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level (range 0 to 1), and rms signal level (also range 0 to 1).
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Adjust your mixer gain settings so that the peak hovers around the
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range 0.1 to 0.5 (the rms will be around 1/2 or 1/3 of the peak, depending
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on your level of impulsive noise and sferics).
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* 7/
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Plot the spectrum file, in my case /tmp/sidspec. This file is two columns,
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bin centre frequency in Hz, and relative power. The file is re-written by
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sidd every 10 seconds or so, depending on your sidd.conf settings. Adjust
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antennas, receivers, etc to obtain desired signal to noise ratios. You
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may want to reconsider the band settings in sidd.conf at this point too.
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* 8/
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Once you're happy with the gain settings, stop sidd and run it again with
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the command
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./sidd -m
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This will read and display the applicable mixer gain settings. Now edit
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your sidd.conf, commenting in the gain commands and putting in your gain
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settings. Then, whenever sidd starts, it will setup the mixer with these
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settings. All mixers will have a line input gain control, but only some
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will have an overall input gain control and/or a record level control.
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The -m option will report what you need to put in the config file.
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* 9/
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Set your PC clock and activate your favourite time synchronisation
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software. Make sure it slews the clock rather than stepping the time.
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* 10/
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Restart sidd in background with
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./sidd -v
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Inspect the log file to make sure your mixer settings have been applied.
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* 11/
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After a period of time, plot some of the data from the output file.
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Output file columns 4 onwards correspond to the 'band' commands in the
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order they appear in sidd.conf. Each column is a total relative power,
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so you will need to apply a square root function during plotting if you
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want to display relative amplitudes.
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* 12/
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After a midnight crossing, make sure sidd has switched to the next
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output file.
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Command line options
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--------------------
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There are just a few command line options - most controls are
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in the config file.
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-v Be a little more verbose with log messages.
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-f Run in foreground. By default, sidd detaches from the process
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group and terminal and becomes a daemon. In foreground mode,
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log messages are duplicated to stderr.
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-m Interrogate the soundcard mixer and report settings, then exit.
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This option overrides any others.
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Miscellaneous notes
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-------------------
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*
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sidd will set the soundcard to the nearest available sample rate to that
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specified in sidd.conf
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*
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Make sure you have enough disk space. The example sidd.conf with 8 bands
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generates files of about 100Mbytes per day, which compress down to about
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30Mbytes. Arrange scripts for plotting. Arrange scripts for compressing
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and archiving files that are a few days old.
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*
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You can specify an ordinary file or a pipe as the input 'device' instead
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of /dev/dsp. In this case, you must set the sample rate in sidd.conf
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to whatever the actual sample rate is. sidd is looking for unsigned bytes
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in 8 bit mode, or signed words in 16 bit mode.
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*
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Once sidd has started up and set the mixer gains, it no longer takes any
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notice of the mixer. Therefore once sidd is running, a rogue user can
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mess things up by twiddling the mixer settings with Xmixer or some other
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utility. Kill off any mixer control panels to avoid the risk of any upset.
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*
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If your PC is set to autoboot after a power outage, you might want to put
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a startup command for sidd into /etc/rc.d/rc.local or similar - but make
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sure the RTC setting commands are done first.
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Revisions
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---------
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v0.9: Original.
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v0.91: Fixes a header file problem with some gcc.
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No longer produces a static binary.
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v0.93: Another bug fixed.
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Added control of mixer input and gains.
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Added stereo mode to make a 2 channel monitor.
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