FG-1025 Family - Technical Note
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What Is Time Of Arrival (TOA)?
Time-Of-Arrival (TOA) is a method of processing sound to distinguish between true glass break
attacks and false alarm sounds. Sounds are received by two microphones, 180
o
opposed, and
processed differently depending on which microphone received the sound first. Sounds arriving
first from the glass zone (front microphone), are processed to determine if a true glass break attack
occurred. Sounds arriving first from the excluded zone (back microphone), are ignored as false
alarm sounds. This innovative technology dramatically increases accuracy, reliability and false
alarm immunity.
Additional FG-1025Z Enhanced Features
The FG-1025Z incorporates three additional enhancements: Remote LED Enable, Trouble Out-
put, and Command Input. Focused on meeting worldwide compliance standards, the Remote
LED Enable feature allows remote operation of the LEDs. The Trouble Output allows remote
annunciations of any trouble conditions the detector may have. The Command Input feature
allows local and remote activation of the detector's self-test.
Solutions To Microphone Overload
Extremely loud glass break events, such as a bullet blowing out a huge window, can overload a
glassbreak detector microphone causing a detector to false alarm or causing a detector to miss a
detection, depending on the circumstances. The FG-930 was the world’s first detector to solve
microphone overload. In a now patented process, a second microphone with a mechanical filter is
able to filter out the overload, allowing the detector to respond normally to the glass break event,
and to reject loud burst false alarms. The FG-730 does not have this feature, so its design treats these
loud burst events as glass break events in order to maximize detection.
An even more ingenious solution is incorporated into the FG-1025 family. A digital filter inside
the microcontroller catches and converts overload signals to normal signals, virtually eliminating
burst related false alarms and significantly improving catch performance of previously “impossible
to detect” glass break events.
