EVAL-315-KEY2 Linx Technologies Inc, EVAL-315-KEY2 Datasheet - Page 3

• Manufacturer Part Number: EVAL-315-KEY2
• Description: RF Modules & Development Tools 2 Button Keyfob Eval Sys 315MHz
• Manufacturer: Linx Technologies Inc

Specifications of EVAL-315-KEY2

• Product: RF Development Tools
• Maximum Frequency: 315 MHz
• Supply Voltage (max): 3 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RANGE TESTING
DEVELOPMENT USING THE PROTOTYPING AREA
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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 will
activate the buzzer on the receiver board, while D1 activates the LED.
As you near the maximum range of the link in your area, it is not uncommon for
the signal to cut in and out as you move. 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 will usually restore 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 by Linx for the products you are testing,
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.
In addition to evaluation functions, the boards may also be used for product
development. The receiver board features a prototyping area for the addition of
application-specific circuitry. This area has connections to V
ground at the bottom that can be used to power any circuitry that is added.
NOTE: If added circuitry requires a higher current than can be provided by the batteries,
the batteries must be removed and the board powered from an external source.
The holes are all plated and are set at 0.100” on center with a 0.040” diameter,
making it easy to add industry-standard SIP and DIP packages to the board. The
data line outputs, RSSI, PDN, and DATA line from the receiver have been wired
out to a header row to the right of the prototyping area. This makes it easy to
connect external circuitry to the module and decoder. Data lines D0 and D1 are
connected to the buzzer and LED, but can be accessed by removing the
resistors next to the D0 and D1 labels.
CC
at the top and to
USING THE BOARDS AS A DESIGN REFERENCE
ABOUT ANTENNAS
IN CLOSING
Since the OEM transmitters are a finished product, most of the designer’s work
will be incorporating the receiver into their design product. The basic evaluation
board included in this kit is very simple, yet illustrates some important techniques
that you may wish to incorporate into your own board layout. You will observe
that the receiver’s mounting pads extend slightly past the edge of the part. This
eases hand assembly and allows for better heat conduction under the part if
rework is necessary. Next, observe the use of a full ground plane fill on the lower
side of the board. This ground plane serves three important purposes:
First, since a 1/4-wave antenna is employed, the ground plane is critical to serve
as a counterpoise (you may wish to read Application Note AN-00500 “Antennas:
Design, Application, and Performance” for additional details on how a ground
plane affects antenna function).
Second, a ground plane will suppress the transfer of noise between stages of a
product as well as unintentional radiation of noise into free space.
Third, a ground plane allows for the implementation of a microstrip feed to the
antenna. The term microstrip refers to a PCB trace running over a ground plane
that is designed to serve as a 50-ohm transmission line between the module and
the antenna. A microstrip is implemented on this evaluation board. If you are
unfamiliar with microstrip calculations, you may wish to refer to the KH2 Series
Receiver Data Guide or the calculator available on our website.
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 you may wish to consider for your design. Included with your 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.
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 541-471-6256 between 9AM and 4PM Pacific
Time to speak with an application engineer.
Legal Notice
All Linx kits and modules 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 legal operation may require
additional permits, approvals, or certifications prior to use, depending on the country of
operation.
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