EVM-915-DTS-BZS Linx Technologies, EVM-915-DTS-BZS Datasheet - Page 12

• Manufacturer Part Number: EVM-915-DTS-BZS
• Description: RF Development Tools 915 MHz Wireless Module DTS Brazil
• Manufacturer: Linx Technologies
• Type: Wi-Fir

Specifications of EVM-915-DTS-BZS

• Rohs: yes
• Product: Evaluation Modules
• Tool Is For Evaluation Of: Wi.232DTSB-R
• Frequency: 915 MHz
• Operating Supply Voltage: 3 V to 3.6 V
• Interface Type: UART
• Factory Pack Quantity: 1

UART Interface
The UART interface is very simple; it is comprised of four CMOS
compatible digital lines.
Figure 16: DTS Series UART Interface Lines
Antenna
The module is designed to work with any 900MHz 50ohm antenna,
including PCB trace antennas.
Antenna selection is usually governed by application requirements.
In general, external antennas perform better. Linx Technologies has a line
of antennas and connectors that are compatible with the modules.
Information on these products is available on our website at
As a rule, a ¼ wave whip or ½ wave dipole antenna with a good, solid
ground plane (well-coupled, 3.5" x 3.5" or larger is optimal) is the best
choice. Dipoles yield better performance than monopoles (whip) when the
ground plane is smaller than optimal. However, many embedded
applications cannot support an externally mountedantenna. If this is the
case, a PCB antenna must be used. The designer can either use an off-of-
the-shelf PCB antenna, such as the ANT-915-SP, or design a trace anten-
na. There are several good antenna tutorials and references on the Internet
and we encourage the designer to use these resources.
Preliminary Draft
www.linxtechnologies.com/antennas.
Pin Description
CMD
Line
RXD
CTS
TXD
Direction
Out
Out
In
In
Description
Clear to send – this pin indicates to the host micro when it is ok to
send data. When CTS is high, the host micro should stop sending
data to the module until CTS returns to the low state.
Command – the host micro will bring this pin low to put the
module in command mode. Command mode is used to set and
read the internal registers that control the operation of the module.
When CMD is high, the module will transparently transfer data to
and from other modules on the same channel.
NOTE: If this pin is low when the module comes out of reset,
the non-volatile registers will be reset to their factory programmed
defaults. It is important to ensure that CMD is held high or left
floating during power-up under normal conditions.
Receive data input.
Transmit data output.
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Link Budget, Transmit Power and Range Performance
A link budget is the best figure of merit for comparing wireless solutions
and determining how they will perform in the field.
In general, the solution with the best link budget will deliver the best
line-of-sight range performance. Improving the link budget by increasing
the receiver sensitivity will result in lower power consumption, while
improving the link budget by increasing the transmit power will result in a
more robust performance in the presence of an on-channel interferer or
multi-path interference.
The transmit power on unlicensed devices is regulated by the FCC. For
transmitters that are not spread-spectrum, the output power is limited to
0dBm (1mW) when a standard ¼ wave whip antenna is used. If the
transmitter operates under the spread-spectrum rules, however, the
transmit power can be increased; up to 1W depending on the spread-
spectrum technique and antennas that are used.
Wireless Fact: Frequency Hopping Spread Spectrum combats in-channel
interference, but at the expense of bandwidth, power consumption, and
latency. Direct Sequence Spread Spectrum does a better job than FHSS at
combating in-channel interference, but at the expensive of occupied band-
width and power consumption. These spread spectrum techniques are
generally chosen because the FCC will allow higher output power from a
transmitter employing these techniques. Recently, the FCC rules changed
to include a new type of spread spectrum device, called Digital Transmis-
sion System (DTS). This method of spread spectrum has no processing
gain, but allows lower cost solutions like the DTS Series to transmit with
higher output power.
To calculate the link budget for a wireless link, simply add the transmit
power, the antenna gains and the receiver sensitivity:
LB = Ptx + Gtxa – SENSrx + Grxa
Note:
proper test equipment. As such, we strongly encourage all of our
customers to use off-of-the-shelf antennas whenever possible.
Antenna design is difficult and can be impossible without the
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Preliminary Draft