Interface Modules - Cisco ASR 903 Quick Start Manual

GNSS Module RF Input Requirements
• The GNSS module requires an active GPS/GNSS antenna with built-in Low-Noise Amplifier (LNA) for optimal performance.
The antenna LNA amplifies the received satellite signals for two purposes:
◦ Compensation of losses on the cable
◦ Lifting the signal amplitude in the suitable range for the receiver frontend
The Amplification required is 22dB gain + cable/connector loss + Splitter signal loss.
The recommended range of LNA gain (LNA gain minus all cable and connector losses) at the connector of the receiver module
is 22dB to 30dB with a minimum of 20dB and a maximum of 35dB.
• GNSS module provides 5V to the active antenna through the same RF input.
• Surge requirement:
◦ GNSS modules have built-in ESD protections on all pins, including the RF-input pin. However, additional surge protection
may be required if rooftop antennas are being connected, to meet the regulations and standards for lightning protection in
the countries where the end-product is installed.
◦ A lightning protection must be mounted at the place where the antenna cable enters the building. The primary lightning
protection must be capable of conducting all potentially dangerous electrical energy to PE (Protective Earth).
◦ Surge arrestors should support DC-pass and suitable for the GPS frequency range (1.575GHz) with low attenuation.
• Antenna Sky visibility:
◦ GPS signals can only be received on a direct line of sight between antenna and satellite. The antenna should see as much
as possible from the total sky. For proper timing, minimum of four satellites should be locked.
Note The antenna terminal should be earthed at the building entrance in accordance with the
ANSI/NFPA 70, the National Electrical Code (NEC), in particular Section 820.93,
Grounding of Outer Conductive Shield of a Coaxial Cable.
• Use a passive splitter if more than one GNSS modules are fed from a single antenna.
The splitter should have all the RF ports capable of DC-pass, if the antenna needs to feed power from
Note
GNSS module.

Interface Modules

The Cisco ASR 903 Router interface modules are a field-replaceable units. In addition to the ports provided on an RSP, the Cisco
ASR 903 Router supports the following interface modules:
6