1. Introduction to Sub-1GHz RF communication
Sub-1Ghz RF (radio frequency) communication is a wireless communication technology that operates in the frequency range below 1 GHz. This range includes several industrial, scientific, and medical (ISM) bands, such as the 433 MHz, 868 MHz, and 915 MHz bands. Sub-GHz RF communication is widely used in various applications, including long-range wireless sensor networks, smart metering, home automation, and industrial control systems. This article provides an introduction to Sub-1Ghz RF communication, including an overview of different modulation techniques used in this frequency range.
1.1. Benefits of Sub-1Ghz RF Communication
Sub-1Ghz RF communication offers several advantages over higher frequency communication systems, such as:
- Longer range: Lower frequencies have better propagation characteristics, allowing for longer communication ranges and better penetration through obstacles.
- Lower power consumption: Sub-1Ghz communication typically requires less power, making it ideal for battery-operated devices. - **Less Congestion**: The Sub-1Ghz frequency bands are less crowded compared to the 2.4 GHz band, resulting in fewer interference issues.
2. Sub-1Ghz modulations with STM32 ecosystem
The sub-1 GHz solutions portfolio of STMicroelectronics includes transmitters, transceivers, modules, and systems-on-chip supporting a host of different applications in home and building automation (Smart Home and Smart City) as well as industrial process control (Smart Factory) and automated metering infrastructures (Smart Grid) or, more broadly, for the Internet of Things (IoT).
These devices support networks operating in the license-free ISM and SRD frequency bands at 169, 315, 433, 512, 868, and 915 MHz as well as several different modulation schemes such as LoRa, 2(G)FSK, (G)MSK, 4(G)FSK, BPSK, OOK, and ASK.
Modulation is the process of varying a carrier signal to transmit data. Different modulation techniques are used in Sub-1Ghz RF communication to achieve various trade-offs between data rate, range, and robustness. Detailed below are some common modulation techniques:
| Modulation type | Description | supported by ST products |
|---|---|---|
| 2/4 - FSK (Frequency Shift Keying) | FSK is a digital modulation technique where the frequency of the carrier signal is varied according to the digital data. | SPIRIT1, S2-LP, STM32WL33, STM32WLx4, STM32WLx5 |
| 2/4 - GFSK (Gaussian Frequency Shift Keying) | GFSK is a variation of FSK where the frequency shifts are smoothed using a Gaussian filter, reducing the bandwidth required for transmission. | SPIRIT1, S2-LP, STM32WL33,
STM32WLx4, STM32WLx5 |
| ASK/OOK (Amplitude Shift Keying) | ASK is a modulation technique where the amplitude of the carrier signal is varied according to the digital data. | SPIRIT1, S2-LP, STM32WL33 |
| BPSK | Binary phase-shift keying (BPSK) is a digital modulation scheme that conveys data by changing, or modulating, two different phases of a reference signal (the carrier wave). | |
| LoRa (Long Range) | LoRa (short for long range) is a spread spectrum modulation technique derived from chirp spread spectrum (CSS) technology | STM32WLx5 |
| Sigfox (DBPSK) | Sigfox modulation is using ultra narrow band (UNB) combined with DPBSK and GFSK. | S2-LP, STM32WL33, STM32WLx4, STM32WLx5 |
3. Sub-1Ghz ST ecosystem
ST Spirit, transmitter and transceiver product family, also support advanced technologies such as frequency hopping, auto-acknowledgment and antenna diversity to secure error-free data transmissions even in harsh environments or challenging logistical conditions.
Sub-1 GHz SoCs of STMicroelectronics, are the first in the world to combine an STM32 architectural basis and a LoRa RF module on the same silicon die. In addition to ease-of-use, affordability, and reliability, they make it possible to optimize BOM costs while being perfectly tailored for a wide range of industrial and consumer applications.
Sub-1 GHz modules, operating in ISM and SMD band, are based on our RF transceivers and are equipped with an antenna, crystal oscillator (xtal) and balun. They provide a ready-to-use solution, fully RF, ETSI, IC, and FCC certified, that helps minimize time to volume.
- STM32WL5Moc (evaluation board : B-WL5M-SUBG1)
3.1. Evaluation boards
RF modules and ICs are supported by an extensive set of evaluation boards, software, firmware, and application notes to help reduce development time and costs.
4. Sub-1Ghz products breakdown pages
For SoCs, all the related application notes are available by following this link. Some of the application notes are highlighted here:
- STM32WLE5/STM32WL55 series:
- AN5481 - LoRaWAN AT Commands for STM32CubeWL: This application note provides guidance on using LoRaWAN AT commands with the STM32CubeWL platform[*].
- AN5406 - How to Build a LoRaWAN Application with STM32CubeWL: This document describes the firmware and steps to build a LoRaWAN application using the STM32CubeWL[*].
- AN5886:Guidelines for design and board assembly of land grid array packages
- More resources are available in the documentation section
- STM32WL3x series:
- AN6098 : Guidelines for FCC standard on STM32WL3x MCUs
- AN5973: Guidelines for bringing up on STM32WL3x MCUs
- AN5923: How to optimize the RF board layout for STM32WL3x MCUs
- AN5920: Guidelines for designing a UART bootloader protocol for STM32WL3 MCUs
- More resources are available in the documentation section
- S2-LP transceiver:
- All S2-LP documentation and application notes are available in the documentation section of the S2-LP ST webpage.
- SPIRIT1 transceiver:
- All SPIRIT1 documentation and application notes are available in the documentation section of SPIRIT1 ST webpage.
Pages in category "Sub-1Ghz"
The following 3 pages are in this category, out of 3 total.