User's Manual

VTU-3 Users Guide
Page 13 of 18
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2.5 Smart Audio:
'Smart Audio' has been included in VTU-3 and is incorporated in several ways. First, as
previously explained, the volume control reports back as “V” is adjusted. Next, when a
'Stolen LoJack' is decoded, at any signal strength, a clean beep will be presented. This is
because the electronics handles-all the decisions regarding squelch and noise and
interpretation of the LoJack signal. Tower signals, and other interference, will be ignored.
When the electronics determines that the beep should be presented, it synthesizes the
audio for clarity. The electronics is expected to be as good, or better than a human ear in
listening for a LoJack signal.
Next, the first time a reply code is decoded, the audio beep will be fairly loud. This is to
get the operators attention in case the operator has turned the volume down very low.
After the first beep, the volume will be at the level set by the operator.
Next, the audio beep will change tone (not volume) in proportion to the signal strength
display. As the signal strength increases, the tone increases. This should result in
tracking without constantly watching the display.
Next, a different tone will be presented when the signal strength becomes full scale. This
will alert the operator to start visual tracking (this is in case the operator is not watching the
display and would not otherwise know that full scale has been reached). Finally, when
tracking an LJU, and another LJU is present, a second, distinctive tone is presented. The
operator may then use the SCAN button to select between the two VLU units.
2.6 LCD Display:
A Liquid Crystal Display (LCD).
A sun shield is not included since the display is more visible and easier to read in daylight,
even in direct sunlight.
A backlight will appear for nighttime viewing whenever there is a display on the screen.
The Reply Code alphabet is constructed from 19 segment characters.
The Signal Strength display is one continuous row of 25 segments. A row of small
reference dots is presented when any signal strength is displayed. This shows the relative
scale of the displayed signal strength bars.
A single rotating arrow presents the direction information.