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Preparing for Wireless Design Certification

Knowledge is power, as they say. When building a wireless product, understanding and preparing for certification requirements can help optimize your design from the beginning so you can pass certifications on the first attempt. This article will cover the key certifications to prepare for as you begin planning your product design.

FCC certifications

Any product to be sold in the U.S. must pass FCC certifications, which include the following:

  • FCC Part 15, subpart B – Unintentional Radiator (EMI): Electronic devices with oscillations greater than 9 kHz that do not deliberately generate radio frequency emissions must comply with FCC Part 15, subpart B emission limits. Today, because devices have much faster clock speeds, this test can be difficult to pass. Faster clocks mean shorter wavelengths; as a result, smaller structures on your PCB can act as an antenna and propagate unwanted emissions. So you really need to minimize this noise in your electronics design.
  • Part 15C, 22, 24, 27 – Intentional Radiator: These tests assess output power and other signal characteristics for products with RF transmitters. Harmonics are the most common cause of test failure, and there are several typical reasons. Here are two common examples:
    Non-linear power amplifiers in the transmitter chain can generate harmonics which are then radiated by the antenna.
    Non-linear PCB components can pick up the fundamental frequency radiated from the antenna and then generate and radiate the harmonics of the fundamental frequency.
  • Specific Absorption Rate (SAR) –This test measures how much the product’s RF transmissions heat human tissue, and is designed to prevent health hazards. If the end product will be used within 20 cm of the human body, you must perform a maximum permissible exposure (MPE) calculation, at a minimum, to determine whether SAR testing is required.

Cellular certifications

Cellular over-the-air (OTA) tests are required for cellular designs with antennas located less than 20 cm from the radio, and are very challenging to pass. Cellular certification testing often includes the following, depending on carrier selection and geographic region:

  • Total Radiated Power (TRP) – Measures total power radiated from the device and is a function of the antenna radiation efficiency, impedance match, and radio output power.
  • Total Isotropic Sensitivity (TIS) – Measures radiated receiver sensitivity integrated over a sphere around the device. It is a function of antenna radiation efficiency, impedance match, and radio receiver sensitivity, but is often limited by noise radiated from host electronics.
  • Relative Sensitivity Intermediate Channel (RSIC) – tests for receiver sensitivity degradation on specific RF channels.
  • Radiated Spurious Emissions (RSE) – evaluates spurious emissions from the cellular transmitter as well as the host electronics

RF Engineering Manager, Kyle Sporre, summarizes PTCRB test requirements, and the regions where they are applicable in the simple whiteboard video session below.

It is very important to understand the design principles that affect certification testing early in your process and to apply best practices. Effectively controlling noise prior to performing radiated cellular tests such as TIS and RSIC can help you achieve the low EMI required to pass certification testing. TIS requires even quieter PCB emissions than FCC certifications, and failures caused by noise coming from the host electronics are common.

Note that products that do not include an antenna within 20 cm of the device are not subject to OTA tests. For example, this includes box products with an antenna port that requires the customer to supply the antenna, or products with cabled antennas that are more than 20 cm from the device. To ensure success, design your product up front with certification requirements in mind. If you need assistance, Digi’s Wireless Design Services (WDS) team can help with your product design, or even correct design issues that can lead to certification failures.

>>Check out additional information on  critical design considerations and the Digi WDS team to get certified today.

Five New Features of the Next Generation of Digi XBee®

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Earlier this week, the Digi XBee Cellular introduced three new variants to the lineup and announced the new features and upgrades of the module platform that combines global connectivity, built-in security, and design flexibility for Internet of Things (IoT) applications:

Digi XBee Cellular

Designed for Verizon, AT&T, and T-Mobile Cat-1 cellular networks.

Digi XBee Cellular LTE-M

Provide OEMs with a simple way to integrate low-power cellular connectivity into their devices.

Digi XBee Cellular NB-IoT 

Provide OEMs with a simple way to integrate low-power narrow-band cellular connectivity into their devices.

These advanced, smart, cellular modems strengthen the already robust Digi XBee product line and are capable of meeting all wireless needs – from cellular, to ZigBee, to Wi-Fi protocols. The platform offers complete design freedom for cellular IoT connectivity integration from LTE Cat-1 all the way to LTE-M and NB-IoT LPWAN technology.

With the new upgrades and features below, organizations looking to integrate cellular connectivity and the ability to standardize on one module platform with a single hardware footprint across products, regions, applications, and cellular networks for everything from local applications to global solutions – regardless of the complexity level.

  1. Programmability: Local intelligence programmed on the modem itself. Business rules engines and application logic can transform data, control local I/O, connect to Bluetooth sensors, actively manage utilization of the cellular link and optimize cellular data plans.
  2. Full USB Support: Supports wide range of applications, from basic to more complex Linux-based applications/systems; direct USB communication for apps with native control requirements.
  3. Bluetooth® Ready: Bluetooth Low Energy (BLE) and Bluetooth Mesh connectivity. Allows simple and quick local setup, provisioning, and troubleshooting capabilities using modern mobile phones and tablets.
  4. Advanced Manageability Features: Support robust over-the-air (OTA) firmware upgrades, Digi’s easy-to-use RF management and configuration tool Digi XCTU, and remote management through Digi Remote Manager™.
  5. Built-In Security: Hardened with built-in Digi TrustFence™ device security.

>>Find more information about the award winning,  next generation Digi XBee cellular products to get started today.

Four Critical Requirements for Intelligent Water Management

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When managing complex drainage districts, distributed lift stations or a municipal water treatment facility, networking and SCADA engineers are tasked with creating and operating safe, efficient water and wastewater management systems for their local and regional communities. In the challenging world of water management, application operating environments are commonly remote and harsh, which makes using 4G LTE wireless networks ideal for connecting remote assets. Below are four critical requirements to consider when upgrading to new technology and network management tools.

  • Equipment Reliability – How long is the warranty of your communication gear? Pumps, PLCs and RTUs are expected to last for years.
  • Flexible Networking Options – It is typical for municipalities to designate a primary and secondary, backup cellular carrier for SCADA telemetry equipment installed across a wide geographic area. The ideal 4G LTE device will support software-selectable carrier switching.
  • System Security – 4G LTE devices and management tools must support guidelines and requirements for water management systems as defined by the Critical Infrastructure Protection (CIP) Act in the U.S. and similar legislation in other countries. It should also enable enterprise security features like access-controlled ports, encrypted data storage, authentic boot and firewalls, as well as connections to security equipment such as IP cameras.
  • Remote Management – Once devices are installed and systems are operational, the challenge of operating a network of distributed telemetry equipment begins. Remote configuration, monitoring and troubleshooting tools are essential.

>>Check out our 4G LTE solution for Water/Wastewater Telemetry and SCADA applications.

Endress+Hauser Chose Digi Connect Sensor+ Cellular Gateway for Inventory Management

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Endress+Hauser, a manufacturer of instrumentation measurement technology for the process industry, looked to Digi to help develop a more robust inventory management system to take better advantage of the data from their flow, level, pressure and temperature measurement devices.

“We are serving the chemical industry, oil and gas, pharmaceutical, food and beverage, primaries and water and wastewater reserve-focused industries,” explains Thiemo Fichter, head of product management inventory management solutions, Endress+Hauser. “There, we can measure pretty much every process variable.”

Most customers were still in the manual inventory monitoring mode, unable to automate the replenishment process to get product when and where they needed it consistently. Digi Connect Sensor helped E+H collect and deliver the information customers needed to make more timely replenishment decisions.

“We provide this inventory information into the business process. Our customers can get everything out of one hand, from the sensor in the physical world via the connectivity of the data, converting this into information up to the level where we integrate this information into our customer’s business process, their ERP landscape.”

In the video below, Ficthter explains why Endress+Hauser chose Digi Connect Sensor+ Cellular Gateway

Learn more about Digi Connect® Sensor+ here >> 

Introducing NB-IoT Technologies for Cellular IoT

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NB-IoT (also referred to as Narrowband IoT or NB1) is another new mobile data standard for the growing LPWA market, part of the latest Release (13) from the 3GPP cellular standards body. Similar to LTE-M, NB-IoT is optimized for lower-bandwidth applications (data rates up to 250Kbps) and ideal for devices that sleep most of the time, waking up to report their data periodically. NB-IoT uses a simple architecture based on single carrier frequency division multiple access and a DSSS modulation scheme, which helps decrease hardware cost and complexity. It supports ultra-long battery life (up to 10 years), extended range (up to 7x better than current LTE technologies) and better building/obstacle penetration for a wide range of applications and use-cases. Some example applications include remote/sleepy industrial sensors, commercial meters, precision agriculture sensors, and a wide range of smart city applications.

NB-IoT is not considered an ‘LTE’ technology. It branches out of the LTE framework, and can be deployed in a number of different ways, such as:

  • 180 KHz band within the GSM spectrum
  • Within an LTE guard band
  • Independent 200KHz frequency band

Regions
Initial NB-IoT deployments in 2017 and 2018 will be primarily in Europe and parts of Asia. Since carriers in the US have already invested heavily in LTE-M infrastructure updates, it is unlikely they will deploy NB-IoT networks in the short-term future.

NB-IoT vs. LTE-M

Key Benefits of NB-IoT

  • Optimized for low-power consumption, even while it is transmitting over the network: Other cellular technologies like LTE-M focus on saving power by sleeping and limiting their transmit time and frequency. NB-IoT excels in its ability to sleep (with support for eDRX) AND minimize power consumption during data transmission, primarily due to the simplified data transmission method and lower data rate, which reduces the need to do power-hungry signal processing and improves the overall efficiency of the system.
  • Less complex radio design with single antenna will be less expensive than other cellular technologies: This will reduce the barrier to entry for new customers and applications to begin integrating low-power cellular technology into their solutions.
  • Improved range and obstacle penetration: With its reduced data rates and simplified radio design, NB-IoT will have stronger link budgets than other cellular technologies, which will lead to greater range/coverage and strong building penetration, great for applications with devices deployed in difficult to reach places.

Digi XBee Cellular NB-IoT
Digi has successfully completed testing of the XBee Cellular NB-IoT in Europe, in partnership with Vodafone. Engineering sample kits are expected to be available by the end of July, customers interested in early testing should contact Digi for more details.

>>Learn how to buy a Digi XBee Cellular Development Kit today with six months of free data.

Introduction to LTE-M Cellular Technology

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Introduction to LTE-M
LTE-M (also referred to as LTE Cat-M or Cat-M1) is a new mobile data standard for the growing LPWA, or Low-Power Wide-Area market. It’s part of the latest Release (13) from the 3GPP cellular standards organization. LTE-M is optimized for lower bandwidth applications, devices that can sleep and report their data periodically. It supports ultra-long battery life capabilities (think multiple years), extended range and better building penetration for devices that might be deployed in ‘hard to reach’ places. It is ideal for use-cases including remote/low-density industrial sensors, automated commercial meters for water or gas systems, connected healthcare devices, and even intelligent industrial lighting systems.

 

 

 

 

New Power-Saving Features of LTE-M
There are two key features built into LTE-M that enable its power efficiency – PSM (Power Savings Mode) and eDRX (extended Discontinuous Reception).

PSM
Power Savings Mode (PSM) allows the device notify the cellular network that it’s going to sleep, and when the network can expect it to wake up based on timer values that are sent by the device. Registration to the network is maintained even while the device sleeps. This means that the device can save battery power, then wake up on schedule to exchange data, or earlier if important information like an alarm needs to be transmitted immediately. It can remain in this registered sleep state for up to 12 days. Once the device wakes up and transmits its payload, it is required to wait and listen for responses from the network for a short period of time (4 idle frames), after which it can go back to sleep in PSM.

eDRX
Extended Discontinuous Reception (eDRX) is a mode that improves power efficiency for cellular devices by reducing the ‘chattiness’ between the device and the network. A normal LTE device is required to be active for a ‘paging cycle’ every 1.28 seconds. An LTE device that leverages eDRX is only required to be active for a paging cycle every 10.24 seconds. This means a device that is connected to the network and communicating or idle is required to be in an active, power-consuming state for about 10x less time, compared to devices that don’t support this mode. eDRX also allows the device to tell the network that it would like to skip some pre-determined number of these 10.24s cycles, extending paging intervals to 40 minutes or more. Both eDRX and PSM save power, but at its core eDRX facilitates reduced power consumption for devices that are awake and connected/idle with the network.

How does LTE-M Compare to Other LTE Technologies?

Top 3 Things to Remember about LTE-M
1. Simpler, less expensive hardware
Devices can connect to LTE networks with simpler modems that only require 1 antenna, because they are half-duplex and have a narrower bandwidth.
2. Longer Battery Life
Devices can leverage the new Power Savings Mode (PSM) and extended discontinuous reception (eDRX) to achieve up to 10 years of battery life
3. Cheaper Data Plans
LTE-M devices will use lower data rates than other LTE devices (typically less than 300Kbps), so they will be less network-hungry, enabling carriers to vastly reduce the monthly cost of data plans for OEMs.

>> Buy a Digi XBee Cellular Development Kit today and get six months of free data.

Design for LPWA with LTE Cat 1 Today. Ready for LTE-M and NB-IoT Networks Tomorrow.

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Build for Today
LTE Cat 1 is a critical cellular technology for low-power, low-bandwidth IoT deployments. While it supports data rates of 10Mbps Downlink / 5Mbps Uplink, it’s not optimal for higher bandwidth applications that require streaming data or large file transfers. LTE Cat 3 or 4 are better suited for applications that require high data rates and are (typically) mains powered, with support for speeds up to 150Mbps Downlink / 50Mbps Uplink. LTE Cat 1, on the other hand, is a great option for LPWA applications that require low-power consumption and transmit smaller amounts of data less frequently. LTE Cat 1 is fully available across North America, so it can be used in customer applications immediately with confidence. With the Digi XBee Cellular and its industry-leading sub-10uA Deep Sleep functionality, OEMs can design their LPWA devices to work with existing LTE Cat 1 infrastructure today, and in the future drop in an ultra-low power Digi XBee LTE-M or NB-IoT (or even LoRa) with little to no hardware or software re-design required.

Ready for Tomorrow
LTE-M and NB-IoT promise to improve range by 4-7x while further enhancing battery life up to 10 years, with significantly lower hardware and data plan costs. However, these new networks are not yet fully deployed and available – carriers are in the early stages of upgrading their infrastructure, with plans to have full service availability that includes new advanced power management features like PSM and eDRX by the end of 2017. It’s a good strategy for OEMs to start LPWA implementations today leveraging LTE Cat 1, allowing a seamless transition to LTE-M and/or NB-IoT as they become fully available in the future.

The Digi XBee line of wireless solutions maintains a consistent hardware footprint, standard pin-out connections and award-winning software interface across a wide variety of communications protocols. They include ZigBee, 802.15.4, DigiMesh, Wi-Fi, as well as longer-range proprietary (100+ kilometer) solutions. Digi XBees manufactured over a decade ago remain hardware and software compatible with the latest XBee products, including the new Digi XBee Cellular LTE Cat 1. Digi’s XBee LTE-M and NB-IoT modems will deliver these new technologies in a fully backwards-compatible and future-proof platform. This is the Digi XBee™ Cellular advantage.

Planning a LPWA solution that needs to work as well in the future as it does today? Digi XBee Cellular LTE Cat 1 is the only modem on the market with the track record to truly connect with confidence.

>>Learn how to buy a Digi XBee Cellular Development Kit today with six months of free data.

Digi XBee Cellular Versus Rudimentary Cellular Breakout Boards

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The Digi XBee Cellular represents a quantum leap ahead of the typical breakout boards on the market today in terms of features, functionality, and ease of development. A breakout board “breaks out” the pins of an underlying cellular module onto a printed circuit board giving you access to use the pins, but little or no additional functionality. Some breakout boards include end-device certification, a SIM slot, and a simple power supply and antenna connector. But, the designer is left having to design in an external microcontroller to manage the module, integrate security elements into their design, and other complex development tasks.

Unlike these breakout boards, Digi XBee Cellular hardware is fully integrated with an on-board cellular module, ARM Cortex M3 microcontroller, power regulator, and security chip, all packed into a compact 24.4 x 32.9mm Digi XBee through-hole footprint. This enables a number of useful features on Digi XBee Cellular that are not available on other cellular modules or breakout boards:

Digi XBee software interface
This runs on the on-board micro-controller and provides an abstraction layer for software designers, including a common AT command interface for configuration and control, an API mode for external devices to intelligently communicate with the XBee, and a transparent serial mode for simple ‘transparent’ communications through the UART, over the cellular network, to the destination IP address or phone number.

Future-Proof design
Digi XBee software interface is consistent across all current and future XBees, and they all share the same Digi XBee footprint. This means it will be easy to drop new wireless technologies into your design as they roll out – technologies like LTE-M, NB-IoT or even LoRa.

• Digi’s easy to use (and free) XCTU software
This software enables you to configure, test, and manage your devices with an intuitive user interface.

• Deep Sleep Mode
In this mode, Digi XBee Cellular consumes less than 10uA. This feature can be configured as cyclic sleep, or pin activated sleep. Other breakout boards support ‘low power modes’ that draw significantly more power.

• Trustfence™ Security Features
These include Secure Boot, SSL/TLS 1.2, Encrypted Storage, and Protected JTAG interface.

• NEW! On-board programmability via MicroPython
Developers will have their own application sandbox directly on the Digi XBee Cellular modem. This enables on-board intelligence for simple sensor/actuator applications, using the digital and analog I/O.

When considering embedded cellular connectivity, it is important consider all of the additional components and work involved in using a breakout board. If time to market and ease of use are vital to your project check out the Digi XBee Cellular development kit which includes a Digi XBee end-device certified modem, a development board, a pre-activated SIM with a live data plan and 6 months of free data service, and the antennas and accessories needed to get cellular up and running in a matter of minutes!

>>Click here to learn more about Digi XBee Cellular.

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