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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 with

 gcc -Wall -O4 -ffast-math -DPENTIUM -Wall -o sidd sidd.c -lfftw3 -lm

which 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 like

 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]

* 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.

* 8/

Once you're happy with the gain settings, stop sidd and run it again with

the command

 ./sidd -m

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.

* 9/ 

Set your PC clock and activate your favourite time synchronisation 

software.  Make sure it slews the clock rather than stepping the time.

* 10/

Restart sidd in background with

  ./sidd -v

Inspect 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 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.

* 12/

After a midnight crossing, make sure sidd has switched to the next

output file.

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.

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.