IoT M2M blog

The home of free hints and tips about wireless IoT / M2M

IoT M2M Cookbook

 IoT M2M Cookbook

How to develop a device based on Wireless Wide Area Network modules

Excerpt of the
IoT / M2M-Cookbook here

Table of contents
1 Why Did I Write the IoT / M2M Cookbook    5
2 Fundamental considerations before starting the IoT / M2M project    7
3 Certifications and approvals    7
3.1 Examples for Radio approvals in EU and US    7
3.2 Examples for Radio approvals in US and Canada (PTCRB)    9
3.3 Examples for automotive related approvals in Europe    9
3.4 SAR – Specific Absorption Rate    10
4 Cellular data communication (GPRS, USSD, SMS, CSD, DTMF)    11
4.1 Voice communication    11
4.2 Modem / acoustic coupler / encryption    11
4.3 DTMF (Dual Tone Multi Frequency)    12
4.4 GPRS (General Packed Radio Service)    12
4.5 SMS    13
4.6 USSD (Unstructured Supplementary Service Data)    13
4.7 Comparison of power consumption (SMS, USSD and GPRS)    14
4.8 CSD (Circuit Switched Data)    15
5 Supply voltage    16
5.1 Power on timing and waiting    16
5.2 Cellular module in power save mode    17
5.3 Internal resistance of batteries and linear voltage transformers    17
5.4 Switched mode voltage regulator    19
5.5 Simulation of a switched power supplies with LT Spice    19
5.6 Capacitors at power supply and cellular module    21
5.7 Supply voltage for GNSS antenna    21
6 Antennas for IoT / M2M devices    21
6.1 Monopole and dipole antennas    21
6.2 Are you sure nothing will interfere with your embedded antenna?    22
6.3 Why do embedded chip or patch antennas have different resonant frequencies?    23
6.4 How will the ground plane affect your embedded antenna?    23
6.5 How to connect your embedded antenna with your wireless module    26
6.6 How to design an antenna matching circuit    27
6.7 Free of charge software to generate a matching circuit automatically    29
6.8 How to switch between an internal and external cellular or GNSS antenna inexpensively    30
7 GPS antenna selection for a tracker    31
7.1 Which GPS antenna types we can select from?    31
7.2 A closer look on Bluetooth / GNSS antennas    32
8 GPS antenna selection for a people or pet tracker    33
8.1 GPS chip loop antenna type A matched to GPS only – test 1    35
GPS chip loop antenna type A matched to GPS / Glonass – test 2    36
8.2 GPS chip loop antenna type A matched to GPS / Glonass – test 3    37
8.3 Effect of the a human or pet body on GNSS antenna type B    38
8.4 Nine different PCB with chip antennas – just one is under test    39
8.5 Return Loss test of the human / pet tracker with and without meat    40
8.6 GPS chip antenna type B  unmatched    42
8.7 Effect the enclosure on GPS chip antenna type B    43
8.8 GPS chip antenna type B frequency drift caused by temperature change    44
8.9 Effect of the cut-out zone without copper under the GPS chip antenna type B    45
8.10 Testing chip antenna performance on the humand hand with a special magnetic probe    47
Test fixture    49
8.11 Why it is impossible to compare the GSM antenna design with a GPS antenna design?    49
9 Examples for IoT devices with embedded antennas    52
9.1 Example: Embedded PCB antenna inside a vending machine    52
9.2 Example: Embedded antennas in Telematic device GPSauge IN1 v.2 of GPSoverIP    53
10 Simulation of an embedded GSM PCB track antenna    53
10.1 Definition of the antenna simulation project    54
10.2 Description of the inverted F antenna    54
10.3 3D model of the simulation    55
10.4 Optimization – determination of antenna shape    56
10.5 Typical requirements of a quad-band GSM antenna    56
10.6 Optimization of the quad-band antenna GSM antenna shape    58
10.7 Directional characteristics of the antenna for two GSM frequencies    58
10.8 Influence of the housing on antenna characteristics    60
10.9 Influence of the ground plane on antenna characteristics    60
10.10 Optimisation of the simulated antenna with matching circuit    62
10.11 Designing in the simulated antenna to a special GSM / GPS tracker    63
10.12 Dos and don’ts during embedded antenna design    65
11 Components around the cellular module    66
11.1 SIM card    66
11.2 SIM card subscription    67
11.3 Low ESR capacitor    67
11.4 ESD protection    68
11.5 Loudspeaker and microphone    68
11.6 Firmware update for the final PCB    68
12 Examples of mistakes and errors during M2M development    69
12.1 Power down reset    69
12.2 SMS errors    69
12.3 CSD errors    70
12.4 IP connection errors    70
12.5 Analysis of several design mistakes in one M2M design    71
12.6 Analysis of mistakes of a PCB track antenna for GSM    71
12.7 Analysis of a GSM chip antenna on a small ground plane    72
12.8 Analysis of a Swiss GSM watch    73
12.9 Analysis of embedded LTE antenna in detail    73
13 Radiation noise, maximum spurious antenna radiation    74
13.1 Antenna radiation versus radiation noise    74
13.2 Conductive noise    76
13.3 Conductive noise transformed to radiated noise    77
13.4 Radiated noise transformed to conductive noise    77
13.5 Prevention against radiated noise    77
14 How to use a vector network analyser for IoT / M2M development    80
14.1 Quick Start Guide Vector Analyser MiniVNA Tiny    82
14.2 Explanation S11, VSWR, return loss, reflection coefficient and antenna bandwidth    84
14.3 Revealing the truth – four cellular antennas tested with MiniVNA    86
14.4 A comparison of three Vector Network Analysers    94
15 Testing your M2M device    100
15.1 TX power peaks by cellular module test mode    100
15.2 Pseudo load of 2 Ampere peak load with self-made function generator    100
15.3 TX power peaks with a GSM tester    102
15.4 Testing of the sensitivity    102
15.5 Testing radiated TX power    102
15.6 Where can you buy a cheap cellular tester?    102
15.7 Example of a measurement report from GSM test equipment    103
15.8 Ripple and peak voltage – visible on GSM test equipment    108
15.9 How to test a UMTS module on foreign band    108
15.10 Testing with UMTS testers    108
15.11 How to test an LTE module on foreign bands    109
15.12 Potential difficulties with LTE modules worldwide    110
15.13 Testing the GNSS module    110
15.14 Measurement of the cellular antenna in 3D    111
15.15 Summary of testing    112
16 AT Commands    112
16.1 AT commands during power on of your cellular module evaluation kit    113
16.2 ”Hello World” for GSM – AT commands to send a SMS    113
16.3 AT commands and logic loops to set up a communication channel    114
17 Project descriptions of IoT / M2M devices    115
17.1 Project description of a long-term tracking device    116
17.2 Project description of a flexible tracking device for bank notes    116
18 Thank you    117

1 Why Did I Write the IoT / M2M Cookbook?

I have worked in the Wireless M2M industry for more than a quarter of a century. Twenty-five years ago, we didn’t even have a word for “M2M” or “IoT”. We developed Machine to Machine devices without knowing that decades later these creations would be called “M2M devices”. Twenty-five years ago, the GSM network for wireless data communication did not exist. I took my first steps in wireless data communication with Frequency Shift Keying (FSK) on Private Mobile Radios (PMR). On PMRs we achieved communication speeds of 3600 bits per second. A little later we started using public analogue trunked radios. These trunked radio systems provided local terrestrial wireless networks on FSK. Years ago, the last public analogue trunked radio network in Germany was taken out of service. GSM jumped in with its Short Message Service (SMS) and Circuit Switched Data (CSD). CSD provided us 9600 bits per second. We could use SMS and CSD for straightforward countrywide data communication. Later on, GSM roaming offered us worldwide data communication. Today, GSM/GPRS is being gradually phased out and is being replaced by 3G and 4G technology.
In the US, the cellular operator AT&T no longer accepts new M2M applications on GSM/GPRS. AT&T will only accept applications on 3G and 4G (UMTS, HSPA, LTE)
. Some people try to differentiate between M2M and IoT. Call it IoT or M2M – it does not matter. Applications for IoT or M2M often use the same wireless technology. IoT is the umbrella term for a number of subsets of wireless data communications. M2M is one of these subsets and maybe one of the oldest. Another subset of IoT is called Industry 4.0 or Industrial Internet of Things (IIoT). Just wait a while and a new buzz world will always come up.
This IoT / M2M Cookbook describes how to develop a tracking device based on cellular and GNSS modules. You can create a telemetric device by ignoring the GNSS aspect. Typical devices without GNSS include cellular routers with Ethernet ports or a cellular to Wi-Fi bridge. Nevertheless, the navigation system for trucks described in this book already uses six different wireless technologies (2G, 3G, GNSS, Classic Bluetooth, Bluetooth Low Energy and NFC) with five different antennas within one enclosure.
Cellular networks for GSM, HSPA and LTE are the popular Wireless Wide Area Networks (WWAN). However, in some regions we have WWAN over CDMA and WiMAX.
Sometimes it is not easy to come up with the appropriate English word for the terms in this book. The common word for SMS in UK is “text message”. In this book, we will consistently use the term “SMS”. A prepaid SIM card in UK is called a “Pay as you go SIM card”. I will typically use the common words specified by ETSI – I will call it a prepaid SIM card. If I use the term “GSM module”, this will cover 3G and 4G modules as well, because the fall-back of UMTS, HSPA and LTE is still 2G (GSM/GPRS). GPS is fundamentally an incorrect term. The Global Positioning System (GPS) is just one out of several Global Navigation Satellite Systems (GNSS) that provide the functionality we refer to as “GPS”. We can currently access the Russian GNSS called Glonass. The Chinese GNSS is called Beidou. At some point we will be able to access the European GNSS called Galileo.

The IoT / M2M Cookbook is intended to help developers of wireless applications save some time and perhaps provide some inspiring ideas. It is a book for makers and summarizes the collective experience across my different jobs. By leading the team of developers that is required to design a mobile GSM/GPS tracking device, I learned to think like a developer of an IoT / M2M device. In over fifteen years of working with manufacturing and distribution, I have repeatedly provided the same hints and recommendations to developers of wireless applications. The origin of this book was a 14-page application note written in July 2010. In May 2012, I made the decision to document the story that I deliver weekly to customers within a book. The goal of this book is to guide developers from the concept stage of an IoT / M2M device all the way to the final mass-produced product. This book will not provide introductory details such as how an inverted F antenna works. To explain those concepts, I will provide links to relevant supporting information. In any case, this book will provide you with information that is often omitted in the official radio module and antenna manufacturers’ documentation. This book shows an inverted F PCB antenna for GSM in detail. It explains how to redesign it with your own PCB and how to encapsulate the whole design in epoxy resin. It also explains how to integrate a chip or PCB antenna with coaxial cable.
Some power supply concepts including LT Spice modules for DC/DC regulators and load generator for the 2 Ampere peak currents are included in the book, too. It should be noted that the power down reset is still the main fault in designs with cellular modules.
I hope you will enjoy reading the book and I hope it will save you some time as well.
If you an interest to get a copy of the IoT / M2M Cookbook then do not hesitate to drop an email to harald.naumann (at) gsm-modem.de

330 Comments

Add a Comment
  1. Hi Antonio,
    You will find an offer in your email inbox as well.
    Best regards
    Harald

  2. Daivesh Sanghvi

    Dear Harald,

    Am very impressed with your profile and excellence of your work. I am curious to gleam through your Cookbook.

    Hopefully our roads will meet in this marketspace.

    Keep doing great work.

    Best Regards,

    Daivesh

  3. Dear Daivesh, you will find an offer in your inbox.
    “I am what I am because my boss shared his knowledge with me 30 years ago” – Harald Naumann, 2017.
    Now I share the current state of the art in LPWAN both online and offline in the IoT-University.
    https://www.linkedin.com/groups/13500663

  4. Hi Harald,

    I am newb to IoT.
    I came across this and found very helpful to me.
    I like to have a copy of this book.

    Thanks.

    Regards,
    Antonio

  5. Dear Harald,

    I am very interested in your profile and excellence of your cookbook. I am hopeful to read your great Cookbook.

    Hopefully you will help curios people to understand the new world in this IOT world…

    Keep doing great work.

    Best Regards,

  6. Shreejith Shivan

    Hi Herald
    Great article. Your work is really impressive. Can you send me a copy of IoT / M2M Cookbook

    Thank you
    Shreejith Shivan

  7. Dear Shreejith, just have a look in your email inbox. You will find an offer 🙂

  8. Hi Oliver, you will find an offer in your inbox. Just ti let you know that I am working on my next “IoT / M2M Cookbook – – How to develop LPWAN technology – real products, real networks”. I am busy for the next few month. 😉

  9. Hi Antonio, I have written the Iot M2M Cookbook to support people in wireless IoT to all offer the world. I will be glad if yiu will be a customer as well. You will find an offer in your email inbox.
    Regards
    Harald

  10. Hello how are you

    I am interested in having this book, please write to me.

    Thank you

  11. Hi Christian, you will find an offer in your inbox.

  12. Michaël Courtade

    Great sites…is there possibility to get the full cookbook?
    Regards.

  13. Morgan Fitzgibbon

    Hi Harald,

    Where can I buy this book?

  14. Souleymane DICKO

    HI dear Harald,
    congratulations for a lot of good work. I need the documentation too please, and i wait your response in linkedin to the conference of Nuremberg.
    Thx in advance!

  15. Hi Morgan, you will an offer in your email inbox. Since three years I sell the IoT / M2M Cookbook direct. I prefer the direct contact to my book reader. The feedback from the readers end in updates or often in projects for matching of the antenna, concepts for new IoT devices up to orders for the development of customised antennas or complete designs for mass production.

  16. Hi Michael, you will find an offer in your email in inbox. if you tell me your application, then I can take care of a set of components as well.

  17. Hello, Harald!
    May I have an offer for your book?

  18. Hi Jacob, you will find an offer in your email inbox. Your order is welcome. BTW, I invested the incoming money in a NB-IoT shield in Arduino footprint. the same PCB can hold a GSM, UMTS or a LTE module as well. Read more here: http://www.gsm-modem.de/M2M/iot-m2m-tools/iot-out-of-the-box-with-nb-iot-module-arduino/

  19. Hello, Harald!
    I am Fernando from Chile. Topics about IoT here are still in “baby diapers”…
    May I have an offer for your book?
    Thanks a lot !

  20. Hi Harald Naumann,

    The topics you have mentioned in the cookbook are really interesting and useful.

    I would like to get a copy of the book.

    Thanks
    Ravi

  21. Alexander Jaiboy

    Hi Harald,

    Very much interested to read this book. I am doing a product development project in this area.

  22. Hello Harald.

    I’m interested in your coock book.
    Please send me an email with the price.

    Greetings.
    Juan Carlos

  23. Hi Harald,
    Your description sounds very promessing to master the challenges in building a wireless communication solution and to understand the different technologies involved. Where can I get the complete recipes so I can start cooking?)
    Thanks, Greeting, eddi

  24. Hello Harald,
    may I have an offer for your book?

  25. Hi Peter, thank you for your order. Maybe you are interested in my NB-IoT adapters for your evaluation. Some more details here:
    http://www.gsm-modem.de/M2M/iot-m2m-tools/iot-out-of-the-box-with-nb-iot-module-arduino/
    http://www.gsm-modem.de/M2M/m2m-news/arduino-footprint-nb-iot-shield-update/
    Best regards from Germany
    Harald

  26. Hi Juan, you got an offer. I will be glad if you will be a customer as well. Maybe you are interested in my NB-IoT adapters with Arduino header for your evaluation. Oot of NB-Iot you can get it with GSM. UMTS, LTE-Cat1 or LTE-CATNB1/M1 module. Some more details here:
    http://www.gsm-modem.de/M2M/iot-m2m-tools/iot-out-of-the-box-with-nb-iot-module-arduino/
    http://www.gsm-modem.de/M2M/m2m-news/arduino-footprint-nb-iot-shield-update/
    Best regards from Germany
    Harald

  27. Dear Fernando, you got an offer by email. I will be glad if you will be a customer as well. Maybe you are interested in my NB-IoT adapters with Arduino header for your evaluation. Oot of NB-Iot you can get it with GSM. UMTS, LTE-Cat1 or LTE-CATNB1/M1 module. Some more details here:
    http://www.gsm-modem.de/M2M/iot-m2m-tools/iot-out-of-the-box-with-nb-iot-module-arduino/
    http://www.gsm-modem.de/M2M/m2m-news/arduino-footprint-nb-iot-shield-update/
    Best regards from Germany
    Harald

  28. Dear Ravi, you got an offer as well. I will be glad if you will be a customer as well. Maybe you are interested in my NB-IoT adapters with Arduino header for your evaluation. Oot of NB-Iot you can get it with GSM. UMTS, LTE-Cat1 or LTE-CATNB1/M1 module. Some more details here:
    http://www.gsm-modem.de/M2M/iot-m2m-tools/iot-out-of-the-box-with-nb-iot-module-arduino/
    http://www.gsm-modem.de/M2M/m2m-news/arduino-footprint-nb-iot-shield-update/
    Best regards from Germany
    Harald

  29. Dear Alexander, you got an offer. I will be glad if you will be a customer as well. Maybe you are interested in my NB-IoT adapters with Arduino header for your evaluation. Oot of NB-Iot you can get it with GSM. UMTS, LTE-Cat1 or LTE-CATNB1/M1 module. Some more details here:
    http://www.gsm-modem.de/M2M/iot-m2m-tools/iot-out-of-the-box-with-nb-iot-module-arduino/
    http://www.gsm-modem.de/M2M/m2m-news/arduino-footprint-nb-iot-shield-update/
    Best regards from Germany
    Harald

  30. Hi Eddi, You will find an offer in your inbox.
    Maybe you are interested in a cellular evaluation kit listed http://iot-university.org/ and here http://www.gsm-modem.de/M2M/iot-m2m-tools/nb-iot-shield-arduino/

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