# Texas Instruments | Debugging Communication Range | Application notes | Texas Instruments Debugging Communication Range Application notes

```Application Report
SWRA603 – March 2018
Debugging Communication Range
Torstein Ermesjo
ABSTRACT
In a RF system having the best possible range is important in many cases. There are many factors that
can cause poor range. This application report provides a step-by-step guide on which parts of the design
could cause shorter range than desired.
Table 1. Definition of Terms
Term
Conducted
CW
1
2
3
4
5
6
7
Definition
The DUT is connected via cable directly to the instrument.
Over the air
Carrier Wave (tone)
Contents
Step 1: Calculate the Theoretical Range .................................................................................
Step 2: ........................................................................................................................
Step 3: Measure the Conducted Sensitivity .............................................................................
Step 4: Measure the Conducted Output Power..........................................................................
Step 5: Antenna Measurements ...........................................................................................
Step 6: Still Issues? .........................................................................................................
References ...................................................................................................................
2
2
2
3
3
3
4
SmartRF is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
SWRA603 – March 2018
Submit Documentation Feedback
Debugging Communication Range
1
Step 1: Calculate the Theoretical Range
1
www.ti.com
Step 1: Calculate the Theoretical Range
1. Read Achieving Optimum Radio Range. This document describes the fundamental equations used to
estimate range and some of the most important factors that impact range.
2. Calculate line-of-sight (LOS) range using the excel sheet linked to Achieving Optimum Radio Range
a. Output power
b. Chip and data rate used
c. Heights of antennas above ground
d. Operating frequency
3. Are there any objects between the LOS of the transmitter and the receiver?
a. If yes, add a suitable absorption material that can represent the object blocking the LOS.
4. Choose an antenna gain that is realistic for your project.
a. Achieving 100% efficiency is not possible. Example: Typical efficiency would be – 4 dBi for a good
433 MHz antenna for a handheld product.
2
Step 2:
If the range is not meeting the expected distance based on the results in Step 1, the root cause needs to
be determined:
Poor range could be caused by one or more of the following factors:
• Poor sensitivity in the receiver
• Poor TX output power
• Poor antenna design (matching)
• Not optimal settings
The measurement methods depend on what type of equipment you have available.
It is highly recommend for the measurements to use SmartRF™ Studio to control the DUT. If that is not
possible, use unmodified settings and code from the software or unmodified code examples before testing
with the settings that are used for the product. This is to ensure that the testing of the hardware is done
with good known software.
3
Step 3: Measure the Conducted Sensitivity
1. Disconnect the antenna and perform conducted measurements at the SMA connector or solder a semirigid coax cable at the 50 Ω point.
2. Preferred: Use a signal generator that is capable of sending data packets. If the signal generator
cannot send data packets, just send preamble data.
3. If a signal generator is not available, use an EM/Launchpad as a transmitter. Use coax cables and
attenuation between the EM SMA connector and the 50 Ω point on the custom board.
NOTE: It is difficult to get an accurate number using this method since the exact values of output
power and attenuation are normally not known.
a. Some energy will also travel over the air from the EM to the DUT. In addition, background noise
could impact the results. To get more accurate results, the receiver should be placed in a shielded
box.
4. If the conducted sensitivity is poor:
a. Are the settings the same as the recommended values from SmartRF™ software? If the sensitivity
is good when using SmartRF Studio and not with the settings used for the project the settings has
to be evaluated.
b. What is the frequency difference between the DUT and the signal source? Ensure that the RF
frequency of the DUT sending a CW is as expected given the tolerance on the xtal used.
2
Debugging Communication Range
SWRA603 – March 2018
Submit Documentation Feedback
Step 4: Measure the Conducted Output Power
www.ti.com
c. Is the schematic according to the reference design including all component values?
d. Is the layout according to the reference design?
4
Step 4: Measure the Conducted Output Power
1. Disconnect the antenna and perform conducted measurements at the SMA connector or solder on a
semi-rigid coax cable at the 50 Ω point.
2. Preferred: Use a Spectrum analyzer. MSP-SA430 or similar does not have the required accuracy. Use
1 MHz RBW for measuring output power and unmodulated carrier on the transmitter.
3. If a SA is not available, then use an EM or Launchpad with a SMA connection point.
a. Add a known RF attenuation block between the transmitter’s SMA connector (50 Ω point) and the
4. If the conducted power is poor:
a. Is the schematic according to the reference design?
b. Is the layout according to the reference design?
5
Step 5: Antenna Measurements
If the conducted sensitivity and conducted output power are as expected, and the range is poor compared
to the estimated range, the antenna efficiency is likely poor. The required tuning is a function of the
ground plane size and the casing meaning that even if the antenna is copied directly from one of our
recommended antenna designs the tuning could be not optimal. The Antenna Measurements section in
the Antenna Selection Guide contains a more detailed description on how to measure antennas than the
summary below.
• Preferred: Use a Network Analyzer (VNA) to accurately tune the antenna. Some mini VNAs are
available on the market with a reasonable price tag if a full featured VNA is not available or cannot be
rented.
– Disconnect the radio and add a semi-rigid coax cable or SMA connector at the 50 Ω point towards
the antenna matching network and antenna.
– Compensate for the length of the semi-rigid cable or SMA with port extensions so they are not
included in the antenna measurements.
– Always measure the antenna in the final casing, otherwise the tuning will be invalid.
– Always measure the antenna as it would be used in the application. If the device is placed on a
metal shelf, the tuning must be made in a similar environment.
– Measure the resonance of the antenna and make sure the matching is better than VSWR 2.
– If the resonance is not correct or the matching is greater than VSWR 2, the antenna design has to
be reviewed again.
• If measurements with a VNA is not possible then use an EM or Launchpad with a known good
antenna.
– Measure the resonance frequency by sweeping the frequency of the transmitter; measure which
6
Step 6: Still Issues?
If you still have issues post a question on E2E.
The minimum post on E2E must contain information about:
• Which chip was used
• Settings
• Software used
• Results from Step 1 through Step 5
SWRA603 – March 2018
Submit Documentation Feedback
Debugging Communication Range
3
References
7
References
•
•
4
www.ti.com
Antenna Selection Guide
Debugging Communication Range
SWRA603 – March 2018
Submit Documentation Feedback
Texas Instruments Incorporated (‘TI”) technical, application or other design advice, services or information, including, but not limited to,
reference designs and materials relating to evaluation modules, (collectively, “TI Resources”) are intended to assist designers who are
developing applications that incorporate TI products; by downloading, accessing or using any particular TI Resource in any way, you
(individually or, if you are acting on behalf of a company, your company) agree to use it solely for this purpose and subject to the terms of
this Notice.
TI’s provision of TI Resources does not expand or otherwise alter TI’s applicable published warranties or warranty disclaimers for TI
products, and no additional obligations or liabilities arise from TI providing such TI Resources. TI reserves the right to make corrections,
enhancements, improvements and other changes to its TI Resources.
You understand and agree that you remain responsible for using your independent analysis, evaluation and judgment in designing your
applications and that you have full and exclusive responsibility to assure the safety of your applications and compliance of your applications
(and of all TI products used in or for your applications) with all applicable regulations, laws and other applicable requirements. You
represent that, with respect to your applications, you have all the necessary expertise to create and implement safeguards that (1)
anticipate dangerous consequences of failures, (2) monitor failures and their consequences, and (3) lessen the likelihood of failures that
might cause harm and take appropriate actions. You agree that prior to using or distributing any applications that include TI products, you
will thoroughly test such applications and the functionality of such TI products as used in such applications. TI has not conducted any
testing other than that specifically described in the published documentation for a particular TI Resource.
You are authorized to use, copy and modify any individual TI Resource only in connection with the development of applications that include
the TI product(s) identified in such TI Resource. NO OTHER LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE TO
ANY OTHER TI INTELLECTUAL PROPERTY RIGHT, AND NO LICENSE TO ANY TECHNOLOGY OR INTELLECTUAL PROPERTY
RIGHT OF TI OR ANY THIRD PARTY IS GRANTED HEREIN, including but not limited to any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
regarding or referencing third-party products or services does not constitute a license to use such products or services, or a warranty or
endorsement thereof. Use of TI Resources may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
TI RESOURCES ARE PROVIDED “AS IS” AND WITH ALL FAULTS. TI DISCLAIMS ALL OTHER WARRANTIES OR
REPRESENTATIONS, EXPRESS OR IMPLIED, REGARDING TI RESOURCES OR USE THEREOF, INCLUDING BUT NOT LIMITED TO
ACCURACY OR COMPLETENESS, TITLE, ANY EPIDEMIC FAILURE WARRANTY AND ANY IMPLIED WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF ANY THIRD PARTY INTELLECTUAL
PROPERTY RIGHTS.
TI SHALL NOT BE LIABLE FOR AND SHALL NOT DEFEND OR INDEMNIFY YOU AGAINST ANY CLAIM, INCLUDING BUT NOT
LIMITED TO ANY INFRINGEMENT CLAIM THAT RELATES TO OR IS BASED ON ANY COMBINATION OF PRODUCTS EVEN IF
DESCRIBED IN TI RESOURCES OR OTHERWISE. IN NO EVENT SHALL TI BE LIABLE FOR ANY ACTUAL, DIRECT, SPECIAL,
COLLATERAL, INDIRECT, PUNITIVE, INCIDENTAL, CONSEQUENTIAL OR EXEMPLARY DAMAGES IN CONNECTION WITH OR
ARISING OUT OF TI RESOURCES OR USE THEREOF, AND REGARDLESS OF WHETHER TI HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
You agree to fully indemnify TI and its representatives against any damages, costs, losses, and/or liabilities arising out of your noncompliance with the terms and provisions of this Notice.
This Notice applies to TI Resources. Additional terms apply to the use and purchase of certain types of materials, TI products and services.
These include; without limitation, TI’s standard terms for semiconductor products http://www.ti.com/sc/docs/stdterms.htm), evaluation
modules, and samples (http://www.ti.com/sc/docs/sampterms.htm).
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265