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| Installation and setup notes for sidd-0.93, 15th March 2005. |
| ------------------------------------------------------------ |
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| You have unpacked the tgz file and have 3 files:- |
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| * README - this one |
| * sidd.c - source code |
| * sidd.conf - a sample configuration file. |
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| Installation steps |
| ------------------ |
| * 1/ |
| You will need FFTW3 from www.fftw.org, if not already installed. |
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| * 2/ |
| 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/ |
| Edit sidd.conf to suit your requirements. |
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| * 4/ |
| Start sidd in verbose foreground mode with the command |
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| ./sidd -vf |
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| * 5/ |
| Examine the log file - it should look something like |
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| 2005/03/15 20:03:17 logfile /root/sidd.log |
| 2005/03/15 20:03:17 los threshold 0.060, timeout 5 seconds |
| 2005/03/15 20:03:17 band LB 18200 18400 |
| 2005/03/15 20:03:17 band AN 19480 19680 |
| 2005/03/15 20:03:17 band SK 22050 22150 |
| 2005/03/15 20:03:17 band BG 23300 23500 |
| 2005/03/15 20:03:17 band TV 20190 20340 |
| 2005/03/15 20:03:17 band NV 16300 16500 |
| 2005/03/15 20:03:17 band B1 20800 21000 |
| 2005/03/15 20:03:17 band B2 22650 22850 |
| 2005/03/15 20:03:17 requesting line input gains left=77 right=100 |
| 2005/03/15 20:03:17 line input gains set to: left=77 right=100 |
| 2005/03/15 20:03:17 taking data from [/dev/dsp] |
| 2005/03/15 20:03:17 requesting rate 48000 |
| 2005/03/15 20:03:17 actual rate set: 48662 samples/sec |
| 2005/03/15 20:03:17 soundcard channels: 1 bits: 16 |
| 2005/03/15 20:03:17 resolution: bins=2048 fftwid=4096 df=11.880371 |
| 2005/03/15 20:03:17 spectrum file: /tmp/sidspec |
| 2005/03/15 20:03:17 using SCHED_FIFO priority 1 |
| 2005/03/15 20:03:17 sidd version 0.93: starting work |
| 2005/03/15 20:03:17 using output file [./050315.dat] |
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| * 6/ |
| Now tail the output file (in my example, ./050315.dat). The first |
| three columns are the timestamp (seconds from 01/01/1970), peak signal |
| level (range 0 to 1), and rms signal level (also range 0 to 1). |
| |
| Adjust your mixer gain settings so that the peak hovers around the |
| range 0.1 to 0.5 (the rms will be around 1/2 or 1/3 of the peak, depending |
| on 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 by |
| sidd every 10 seconds or so, depending on your sidd.conf settings. Adjust |
| antennas, receivers, etc to obtain desired signal to noise ratios. You |
| may want to reconsider the band settings in sidd.conf at this point too. |
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| * 8/ |
| Once you're happy with the gain settings, stop sidd and run it again with |
| the command |
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| ./sidd -m |
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| This will read and display the applicable mixer gain settings. Now edit |
| your sidd.conf, commenting in the gain commands and putting in your gain |
| settings. Then, whenever sidd starts, it will setup the mixer with these |
| settings. All mixers will have a line input gain control, but only some |
| will 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. |
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| * 9/ |
| Set your PC clock and activate your favourite time synchronisation |
| software. Make sure it slews the clock rather than stepping the time. |
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| * 10/ |
| 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/ |
| 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 the |
| order 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 you |
| want to display relative amplitudes. |
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| * 12/ |
| After a midnight crossing, make sure sidd has switched to the next |
| output file. |
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| Command line options |
| -------------------- |
| There are just a few command line options - most controls are |
| in the config file. |
| |
| -v Be a little more verbose with log messages. |
| -f Run in foreground. By default, sidd detaches from the process |
| group 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. |
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| Miscellaneous notes |
| ------------------- |
| * |
| sidd will set the soundcard to the nearest available sample rate to that |
| specified in sidd.conf |
| |
| * |
| Make sure you have enough disk space. The example sidd.conf with 8 bands |
| generates files of about 100Mbytes per day, which compress down to about |
| 30Mbytes. Arrange scripts for plotting. Arrange scripts for compressing |
| and archiving files that are a few days old. |
| |
| * |
| You can specify an ordinary file or a pipe as the input 'device' instead |
| of /dev/dsp. In this case, you must set the sample rate in sidd.conf |
| to whatever the actual sample rate is. sidd is looking for unsigned bytes |
| in 8 bit mode, or signed words in 16 bit mode. |
| |
| * |
| Once sidd has started up and set the mixer gains, it no longer takes any |
| notice of the mixer. Therefore once sidd is running, a rogue user can |
| mess things up by twiddling the mixer settings with Xmixer or some other |
| utility. 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 put |
| a startup command for sidd into /etc/rc.d/rc.local or similar - but make |
| sure 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. |
| |