emergency loudspeaker system on roof

Indoor Speaker Unit (ISU)

The Indoor Speaker Unit (ISU) is an integral part of the ATI system. The ISU provides 400 Watts of continuous audio output power for reliable indoor alert tone notification, voice instruction and public address in emergency situations. The ISU is monitored, controlled and activated by the ATI Communications Control Unit (CCU).


Standard Features

  • NEMA-4/3R enclosure
  • Remote Terminal Unit (RTU) controller board
  • Temperature-compensated battery charger
  • Power on/off circuit breakers and intrusion switch
  • 400 Watt Class D Amplifier
  • Conventional VHF or UHF radio and mounting hardware
  • 25 volt and 70 volt audio output line for driving long speaker wire runs with minimum losses
  • Simple and compact hardware design
  • Field-proven reliability
  • Exceptional acoustic performance and intelligibility
  • Unique, compact and highly-efficient Class D amplifier
  • 400 Watts of continuous audio output power
  • Supports 30 minutes of continuous activation
  • Built-in tone generator providing for eight standard, pre-configured tones
  • 127 pre-recorded voice messages, up to 30 minutes of recording time
  • Local and remote testing and reporting with silent test option
  • Standard VHF and UHF radio receives and transmits FSK, DTMF and Two Tone Sequential (TTS) data signals
  • Automatic gain control for consistent output volume
  • Very low standby power requirements
  • Message encryption and security coding prevent unauthorized system activations
  • Conformal-coated printed circuit boards for operating in harsh environments
  • Temperature-compensated battery charger ensures batteries are at full capacity
  • Meets UFC and FEMA requirements

Optional Features

  • Custom alert tones and digital messages
  • Advanced Communication Board upgrade to MP3/WAV digital voice messaging and Mini-SD flash memory card for easy message replacement, supports 255 messages and over 100 hours of recording time
  • Local control panel upgrade with microphone, LCD display and controls
  • Trunked radio upgrade
  • Flexible, redundant communication options including IP, Ethernet, twisted pair/phone line, cellular, satellite
  • Antenna surge protector option
  • Strobe light and LED sign output options
  • Choice of speaker type and configuration
  • NEMA-4/3R stainless steel enclosure upgrade

Spec Sheet (PDF)

Download Spec Sheet