BRX-XLR User Guide
14
180-0145-001-R05
As can be seen, there is a general trend that drives towards the midpoint of the loop as the total loop
length increases. Having said that, service providers have a finite amount of locations per loop where
they can install the BRX-XLR which will not always be at the optimum point. Positron Access has
designed the BRX Cloud Calculator tool to assist in determining the optimum location for any given
loop along with many suggested alternative placements with predicted performances.
3.5 BRX Cloud Calculator
To view the impact related to the installation of a BRX-XLR unit on a given loop whether it is a 26
AWG (0.40mm), 24 AWG (0.51mm) or a 22 AWG (0.64mm) copper pair, a cloud-based BRX
Calculator is available. All you need to do is request access via the Positron Access Portal at
http://www.positronaccess.com/Portal.php
You will then be sent a username and password to access
the
Portal.
The
BRX
Calculator
can
then
be
accessed
directly
at
http://brx.calculator.positronaccess.com/
The BRX Cloud Calculator has three tabs at the bottom that can be used for the following objectives:
Calculate the achievable bandwidth based on the location of the BRX-XLR (from the DSLAM)
and the distance to the subscriber CPE;
Calculate the optimal bandwidth for a specific total loop length and gauge of wire and
recommend the location where the BRX-XLR should be installed (usually a range of distances
from the DSLAM) to achieve the target bandwidth;
Calculate the best placement of a BRX-XLR cabinet to achieve a target bandwidth to multiple
subscribers over a total loop length. This is useful to determine the Customer Serving Area
(CSA) for a given access speed tier.
Please feel free to request a copy of our BRX-XLR Calculator Quick Start Guide (180-0157-001) for
any assistance with using this tool.
3.6 Miscellaneous Other Placement Guidelines
3.6.1 Bonded Pairs
For convenience, the BRX Cloud Calculator does include an option (checkbox) for pair bonding. This
feature assumes that the two loops are essentially identical and therefore doubles the resulting
bandwidth for both downstream and upstream. In reality, bonded pairs are often not the same length.
It is recommended to enter the longest loop in the calculator in order to optimize placement for this
loop. Since the other loop is shorter, the resulting bandwidth resulting from the bonded pairs should
be slightly better than what the calculator will predict.
3.6.2 Actual Raw Throughput is Different from Predicted Values
There will be times when actual raw throughput will be significantly different (>10%) from predicted
values from the calculator. This may be caused by a number of factors. One of the most likely reason
is that the Target SNR default value in the BRX Cloud Calculator (set to 6dB), is not the same as the
