Users Manual

7
Modulation method
This Device uses Frequency Hopping Spread Spectrum (FHSS) as its modulation technique. The list of
frequencies are as follows:
Frequency in Mhz
902.3
902.5
902.7
902.9
903.1
903.3
903.5
903.7
903.9
904.1
904.3
904.5
904.7
904.9
905.1
905.3
905.5
905.7
905.9
906.1
906.3
906.5
906.7
906.9
907.1
907.3
907.5
907.7
907.9
908.1
908.3
908.5
908.7
908.9
909.1
909.3
909.5
909.7
909.9
910.1
910.3
910.5
910.7
910.9
911.1
911.3
911.5
911.7
911.9
912.1
912.3
912.5
912.7
912.9
913.1
913.3
913.5
913.7
913.9
914.1
914.3
914.5
914.7
914.9
The FCC regulations for systems using frequency hopping spread spectrum (FHSS) techniques
can be summarized as follows:
 Frequency hopping systems shall have hopping channel carrier frequencies separated by a minimum of
25 kHz or the 20 dB bandwidth of the hopping channel, whichever is greater. The system shall hop to
channel frequencies that are selected at the system hopping rate from a pseudo randomly ordered list of
hopping frequencies. Each frequency must be used equally on the average by each transmitter (Ref:
15.247(a)(1))
 If the 20 dB bandwidth of the hopping channel is less than 250 kHz, the system shall use at least 50
hopping frequencies and the average time of occupancy on any frequency shall not be greater than
400ms within a 20 second period (= 0.4 * 50 channels). If the 20 dB bandwidth of the hopping channel
is 250 kHz or greater, the system shall use at least 25 hopping frequencies and the average time of
occupancy on any frequency shall not be greater than 400 ms within a 10 second period (= 0.4 * 25
channels). In addition the maximum allowable 20 dB bandwidth of any hopping channel is 500 kHz
(Ref: 15.247(a)(1)(i))
 The maximum peak conducted output power shall not exceed 1 W (+30 dBm) for systems employing at
least 50 hopping channels and 250 mW (+24 dBm) for systems employing less than 50 hopping
channels, but at least 25 hopping channels. As opposed to systems employing digital modulation,
averaging measurement methods are not permitted (Ref: 15.247(b)(2))
MCU STM32L433xx
The STM32L433xx devices are the ultra-low-power microcontrollers based on the high performance Arm®
Cortex®-M4 32-bit RISC core operating at a frequency of up to 80 MHz. The Cortex-M4 core features a
Floating point unit (FPU) single precision which supports all Arm® single-precision data-processing instructions
and data types. It also implements a full set of DSP instructions and a memory protection unit (MPU) which
enhances application security.
The STM32L433xx devices embed high-speed memories (Flash memory up to 256 Kbyte, 64 Kbyte of SRAM),
a Quad SPI flash memories interface (available on all packages) and an extensive range of enhanced I/Os and
peripherals connected to two APB buses, two AHB buses and a 32-bit multi-AHB bus matrix.
The STM32L433xx operates in the -40 to +85 °C (+105 °C junction), -40 to +105 °C (+125 °C junction) and -40
to +125 °C (+130 °C junction) temperature ranges from a 1.71 to 3.6 V VDD power supply when using internal
LDO regulator and a 1.05 to 1.32V VDD12 power supply when using external SMPS supply. A comprehensive
set of power-saving modes allows the design of low-power applications.
RF Transceiver SX1276