This is the mode to use when you want to detect a signal that is mixed in with other signals as might be observed when using one of the wide-band infrasignal modes.
The radio can process infrasignals from several sources, such as infrasonic microphones, infrasonic hydrophones and extremely large loop antennas, all of which can contain multiple signals. This mode scans the frequency range of 1 Hz to 30 Hz in 16 channels and uses narrow band filters to separate the signals. This mode of operation can be used with or without the alarm function turned on.
In this display, if the alarm function were turned on it would alarm if either one or both signals were to cross the alarm threshold level. See more details in the 16 CHANNEL SCAN – ONE SIGNAL paragraph.
In this display, the alarm function is turned on and a relative strong test signal is used.
In this case it was detected and peaked in channel 12. When the signal level approaches the alarm threshold (red dotted line), it turns yellow. When it crosses the alarm threshold the first time the signal level turns orange and pauses for a few seconds to take a second measurement. If the signal level crosses the alarm threshold durning the second measurement, it will turn red and sound the alarm. Making a second measurement greatly reduces the chance that a noise spike will cause a false alarm.
Occasionally you may want to watch for an infrasignal who’s frequency you’re not quite sure of. You don’t want to scan the whole frequency band, because it takes over one and a half minutes to scan the 16 channels and you might miss an abrupt signal.
First, determine the channel number of the frequency you’re not quite sure of. Touch the OPTIONS >> USER GUIDE buttons. Go to PAGE 5. In the paragraph “5 CHANNEL SCAN.” there is a list of channel numbers and corresponding upper and lower frequencies. Select the channel number that most likely covers the right frequency. Touch the GO BACK TO MODE >> 5 CHANNEL SCAN mode buttons, if not already selected. Then use the left <CHANNEL or right CHANNEL> buttons and continue to touch until the channel number indicated on the status bar is the one you selected from the list.
The scan will start on the channel you selected. It will scan to the right, then scan to the left, back and forth across the five channels. You can speed up the scan by touching SCAN FASTER, but with a tradeoff. The signal strength measurement may not peak as strong and you may miss a very weak signal.
When an infrasignal appears in a channel off to one side of center, the scan can be adjusted using the left <CHANNEL or right CHANNEL> buttons.
To monitor the infrasignal, touch the 1 CHANNEL ON CHART button when the proper channel number appears on the status bar. To measure its frequency, touch 1 CHANNEL ON SCOPE >> MEASURE FREQUENCY.