UNATTENDED OPERATIONS
(When the station works automatically)
What you see in the picture is my station. The equipment is unattended, and receives and stores sonograms.
This is a fundamental step in the monitoring system evolution. Even if you have time to monitor the band one hour a day, all events occurring in the remaining 23 hours are lost.
Some natural radio signals may appear once per day or per month, lasting only few seconds.
Even with good aerials and quiet locations the chance of receiving those signals is very little without continuous monitoring.
Unattended operations with a PC is easy and inexpensive. You only need some freeware program available on Internet. The automatic monitoring may also be used for other frequency bands, not necessarily under 22 kHz.
Main purpose of the automatic operation is to save spectrograms.
Saving the original signal in .WAV format is the most complete possibility but your hard disk will be filled in a day, even at a slow sampling rate (about 1 GB per day at 5.5 ks/s 16 bit in mono, 2 GB for stereo…).
Then it will take long time to analyze acquired data.
To store spectrograms is more practical and saves space; spectrograms are then easy to review.
To acquire data I use Spectrogram in ‘scan-input’ function.
The following example shows my program settings to monitor 0-86 Hz band.
Two antennas are connected to the SoundBlaster L and R channels, to simultaneously compare signals from different reception systems.
Every day or so I look quickly to the saved pictures with an image browser like ACDSee32 (shareware, see http://www.acdsystems.com).
Only 1 or 2 percent of all pictures contain something new or interesting and are then saved. In this way you will quickly build an archive, composed by selections from thousands of spectrograms, and you will be able to document all phaenomena receivable with your system.
And this happens while you are with your friends, or sleep deeply, or are in holiday with your partner…
The most important fact is: you will be able to compare results with other monitors. Many signals may be of local (human) origin; comparisons are extremely important.
Telluric Currents
