Using The Rf Sentry On The Bsr 2000; Power Level Measurement - Motorola BSR 2000 Configuration And Management Manual

BSR 2000 Configuration and Management Guide

Using the RF Sentry on the BSR 2000

The BSR 2000 provides an RF Sentry upstream Spectrum analysis tool. The RF
Sentry tool is used to measure either power levels or signal to noise ratios of each of
the eight upstream ports. The RF Sentry works by means of the Fast Fourier
Transform (FFT) algorithm for power level measurement or Signal to Noise Ratio
(SNR) measurement.
The RF Sentry has its own RF path which can be switched between the RF paths of
the eight upstream ports. The RF Sentry uses a "tap-in" mode to access the RF path.
Both power level and Signal to Noise Ratio measurement is done within the
Broadcom chip set (BCM3138/BCM3140).
Note: In a DOCSIS 2.0 environment, RF Sentry power level or SNR
measurement is only supported on logical channel 0. S-CDMA mode is also
not supported.

Power Level Measurement

The FFT processor measures the power levels of a signal in one of the upstream
receiver ports that spans a range of frequencies. Power level measurement provides an
informational "big picture" of the signal in a particular upstream port. The power
level measurement data can then be displayed to determine power level estimates at
different frequencies across the Spectrum over time. This information can then be
used for upstream Spectrum trend analysis.
This section describes the following tasks:
6-32
Power level measurent is done by means of the Fast Fourier Transform (FFT)
algorithm. FFT transforms a discrete signal in a time domain to a power level in a
frequency domain. Power level measurement is done through a built-in FFT
processor.
SNR measurement is done by exchanging data between a reference modem and
the CMTS. A reference modem is a registered cable modem that is selected to
send an upstream traffic/burst used to measure the SNR on that upstream.
Configuring FFT
Configuring the FFT Processor
Displaying the FFT Processor Configuration
Starting FFT Power Level Measurement
MGBI
Release 1.0
526360-001-00 Rev. B