Linx Technologies OEM Transmitter Evaluation Kit - Manual (Page 7)

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About Antennas
The choice of antennas is one of the most critical and often overlooked
design considerations. The range, performance and legality of an RF link
are critically dependent upon the type of antenna employed. Linx offers
a variety of antenna styles that can be considered for a design. Included
with the kit is a Linx connectorized whip antenna that should be connected
prior to using the kit. Despite the fact the antenna is not centered on the
board’s ground plane, it exhibits an outstanding VSWR of <1.7 and suitably
demonstrates the module's best practical performance.
In Closing
Here at Linx, “Wireless Made Simple” is more than just our motto, it is
our commitment. A commitment to the highest caliber of product, service
and support. That is why, should you have questions or encounter any
difficulties using the evaluation kit, you’ll be glad to know many resources
are available to assist you. First, check carefully for the obvious, then
visit our website at www.linxtechnologies.com or call +1 541 471 6256
between 8AM and 4PM Pacific Time to speak with an application engineer.
Range Testing
Complex mathematical models exist for determining path loss in many
environments. These models vary as the transmitter and receiver are
moved from indoor operation to outdoor operation. Although these models
can provide an estimation of range performance in the field, the most
reliable method is to simply perform range tests using the transmitter and
receiver in the intended usage environment.
Simple range testing can be performed with the transmitter and receiver
evaluation board. To prepare the board for range testing, simply turn it
on by switching the power switch to the ON position. Pressing D0 on the
transmitter activates the buzzer on the receiver board, while D1 activates
the LED.
As the maximum range of the link in an area is approached, it is not
uncommon for the signal to cut in and out as the transmitter moves. This
is normal and can result from other interfering sources or fluctuating signal
levels due to multipath. Multipath results in cancellation of the transmitted
signal as direct and reflected signals arrive at the receiver at differing times
and phases. The areas in which this occurs are commonly called “nulls”
and simply walking a little further usually restores the signal. If this does not
restore the signal, then the maximum effective range of the link has been
reached.
To achieve maximum range, keep objects such as your hand away from
the antenna and ensure that the antenna on the transmitter has a clear and
unobstructed line-of-sight path to the receiver board. Range performance
is determined by many interdependent factors. If the range you are able to
achieve is significantly less than what is specified for the products being
tested, then there is likely a problem either with the board or the ambient
RF environment in which the board is operating. First, check the battery,
switch positions, address settings, and antenna connection. Next, measure
the receiver's RSSI voltage with the transmitter turned off to determine
if ambient interference is present. If this fails to resolve the issue, please
contact Linx technical support.
Legal Notice: All Linx kits are designed in keeping with high
engineering standards; however, it is the responsibility of the user
to ensure that the products are operated in a legal and appropriate
manner. The purchaser understands that the legal operation may
require additional permits, approvals, or certifications prior to use,
depending on the country and operation.