Circular And Linear Versions - KVH Industries TracVision R1ST User Manual

TracVision M5/M7 User's Guide
Chapter 1 - Introduction

Circular and Linear Versions

LNB Skew Angle
8
Your TracVision system is configured to receive either circularly
polarized satellite signals (e.g., North America) or linearly polarized
satellite signals (e.g., Europe or Latin America). Figure 1-3 illustrates
the difference between these two polarizations.
Figure 1-3 Polarizations of Satellite Signals
Circular
Signals transmitted in two
"corkscrew" patterns, one
running clockwise and one
running counter-clockwise
Since linear satellite signals are oriented in a precise cross pattern, the
TracVision antenna's receiving element, called an LNB (low-noise
block), must be oriented in the same way to optimize reception. This
orientation adjustment is referred to as the LNB's "skew angle."
Figure 1-4 illustrates how skew determines the amount of a linear
signal that the LNB collects. The more signal, the better the reception.
Figure 1-4 How Skew Works
Bad Skew
= Satellite Signal
Linear
Signals transmitted in vertical
and horizontal "waves" offset
exactly 90º from each other
Good Skew Ideal Skew
= LNB "Signal Collector"