In-building public-safety DAS bolstered with bidirectional amplifier

Aug. 2, 2023
Comba Telecom’s BDA serves as a headend when connected to remote units and battery backup units.
Comba Telecom
Comba Master Unit

Comba Telecom recently introduced the CriticalPoint NG 700/800 MHz Public Safety Fiber DAS. The NG (Next Generation) system is powered by the company’s just-released public safety CriticalPoint Bi-Directional Amplifier (BDA) NG, which serves as a headend when connected to 0.5W or 2W remote units (RU) and one or more fully integrated battery backup units (BBU).

The system’s RUs are based on the company’s CriticalPoint NG BDA, which the company says “offers built-in customizable cavity filtering, improved advanced digital filtering, improved uplink and downlink ALC [automatic level contron] mechanisms, and the ability to bypass half of the LNA [low noise amplifier] circuitry to allow for utilizing lower gain without raising the noise floor.”

The NG RUs use the same BBUs as the company’s power backup solution. “In a fiber DAS, the NG BDA will function as the master unit (pictured) to provide management for the DAS, while providing downlink power for local service antennas,” Comba explained.

The NG system offers what Comba characterizes as a true end-to-end Class A fiber DAS, “meaning that Class A functions as narrow band filtering, channelizing ALC and squelch can be applied at both the remotes and head-end device,” the company said.

RUs are available with either 0.5W or 2W of downlink power, and can be ordered as either single-band or dual-band devices. They are available in Class A or Class B versions.

A single BDA NG supports up to 32 RUs, using up to four fiber-optic expansion units. Both the master unit and the remote units are available with either 0.5W or 2W of power “for providing local coverage through service antennas,” Comba added.

Single-band models provide up to 64 channels per band, and on dual-band models, up to 96 channels can be shared across bands.

The CriticalPoint NG 700/800 MHz Public Safety Fiber DAS also offers the following capabilities and characteristics.

  • Supports P25 P1/P2, digital and conventional analog communications simultaneously
  • Built-in cavity filtering to protect the unit from interference from FirstNet Band 14 and other neighboring bands
  • Supports up to 32 remote units
  • The master unit and remote units have the same output power for coverage
  • Built-in mandatory isolation test to prevent system oscillation
  • Auto shutdown with alarm upon oscillation detection
  • Web-based GUI for intelligent configuration; SNMP-supported
  • Integrated battery charger unit
  • License-based switching between Class A or Class B, single band or dual band
  • NFPA/IFC/UL 2524-compliant dry contact alarms and built-in visual/audio annunciator

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