The relation between the TX-Power in dB and the raw value used in RAILTest is given by this:
To make the conversion easy the INS14664: Introduction to MaxPowerCalc has been added in Simplicity Studio.
#define 0dBmMeasured // dBm Value measured by raw power setting 24,
// remember to counteract for cables in the setup.
#define wantedOutputPower // The dBm PA output power wanted for the customers application
#define scaledPower (wantedOutputPower - 0dBmMeasured) // intermediate variable for use below
#define rawPASetting (0.000133848*(scaledPower)^5 + 0.001042021*(scaledPower)^4 \
– 0.005109317*(scaledPower)^3 + 0.11773548*(scaledPower)^2 \
+ 3.007063918*(scaledPower) + 24.35849668)
The raw values are used in RAILTest (please make sure to use lower case letters "raw" in RAILTest )
and the settings in the Z-Wave SDK application code are set in "config_rf.h" in dBm:
// The maximum allowed Tx power in deci dBm
#define APP_MAX_TX_POWER 0 // set to 0 dBm by default in the Z-Wave SDK
// The deci dBm output measured at a PA setting of 0dBm (raw value 24)
#define APP_MEASURED_0DBM_TX_POWER 0 //Set to 0 to measure the 0 dBm
// This is set to 33 by default to support the development boards in the Z-Wave SDK
Plot of the raw value as a function of the ScaledPower (in dBm on the RFpin).
The maximum raw value in RAILTest is limited to 155 and the TX power max is 13dBm on the RFpin
More information can be found in
INS14283-6 Bring-up/test HW development, 4.5.1 How to Adjust the PA Output Power Using RailTest
INS14259-9 Z-Wave Plus V2 Application Framework SDK7, 6.3 Setting Up config_rf.h
I’m designing a Z-Wave 700 Slave or Controller Device. What is the recommendation on antenna design and the use of SAW filters?
For Z-Wave gateways (outside EU freq.) with LTE embedded, it is recommended to analyze the specific need for a SAW filter in depth. Optionally, a SAW filter bank can be added and controlled via the SAW0 and SAW1 output pins for operation in different regions.
The UZB7 Controller Reference Design can be found as part of the Z-Wave 700 SDK Documentation. After the SDK is downloaded through Simplicity Studio, the documents can be found here:
UZB7 reference design and Antenna guidelines can be found in these documents:
INS14487 - Z-Wave 700 Integration Guide
PHD14501 - UZB-7 Z-Wave 700 USB Stick Reference Design
How do I adjust the TX power on Z-Wave 700 Controller devices to comply with local regulatory authorities?
You can change the transmit power in 2 different ways:
Using the PC Controller
The PC Controller can change TX Power in the ‘Transmit Settings’ menu.
The TX power can then be changed:
Using the Z/IP Gateway
The TX power level can be adjusted in the configuration file of Z/IP Gateway using the two settings:
The Z/IP Gateway documentation can be found in Doxygen. The default location is:
How do I adjust the TX power on Z-Wave 700 Slave devices to comply with local regulatory authorities?
The TX power should be set by modifying the file config_rf.h. This file contains 2 defines:
#define APP_MAX_TX_POWER 0 #define APP_MEASURED_0DBM_TX_POWER 33
APP_MEASURED_0DBM_TX_POWER is a int8 value for tuning of TX power to 0 dBm in a conducted environment. During the turning process, 'APP_MAX_TX_POWER' should be 0 (0dBm).
APP_MAX_TX_POWER is a int8 value from -128 to +127 deci dBm (-12.8dBm to +12.7dBm) and is for adjusting TX power by the application framework after completion of TX power tuning.
In order to set maximum power, use:
// The maximum allowed Tx power in deci dBm #define APP_MAX_TX_POWER ETXPOWERLEVEL_DEFAULT //= 127 // The deci dBm output measured at a PA setting of 0dBm (raw value 24) #define APP_MEASURED_0DBM_TX_POWER 0
Procedure for setting TX power
a) Set APP_MAX_TX_POWER to 0 and set APP_MEASURED_0DBM_TX_POWER to 0 and compile the application
b) Do a conducted measurement of the TX power with these settings on the product. It is important that this is done on the finished product.
c) Set the APP_MEASURED_0DBM_TX_POWER to the measured, conducted value.
d) Set the APP_MAX_TX_POWER to the desired/allowed TX power in the region where the product are to be used.
e) Compile the firmware
f) Perform the regulatory radiated measurements with the regulatory limit value (step d), e.g. 50 deci dBm (5 dBm). If the regulatory measurements allow for a e.g. ½ dB more, then change the deci dBm to 55 and re-compile. If the radiation is too high in one direction and e.g. ½ dB less is needed, then change to 45 deci dBm and recompile.
Why do I need to use a SAW filter in my design?
In several regions, upload in the LTE band occurs at frequencies located closer than 10 MHz from frequencies used by Z-Wave. Due to the high power level allowed, in addition to the loose restrictions on side band emissions granted to the LTE band, the LTE upload may interfere significantly with the operation of a listening Z-Wave node located nearby.
To reduce the impact from other devices, the Z-wave device must incorporate a SAW filter which attenuates these technologies, thus preventing saturation of the receiver.
The effects of interference from LTE is outlined in LTE Case Study.