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

384 Comments

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  1. Hi Davide, you will find an offer in your inbox as well. I will be glad to have another reader in Italy. Please note that I was in April in Milano at M2M Forum.

  2. Hi Harald

    In 2009 I filed a patent on the intelligent solar panel which contains all your favourite M2M ideas embedded in a Photovoltaic Array. Really wild thinking but based on the fact that I joined the radio division of what is now BT Labs 45 years ago. None of us called it IoT or M2M in those days it was just the obvious thing to do. EU patent number EP2386123. UK, Australian and S African patents granted, US and Japan close.

    Looking for an investor to take this to market….

    Colin

  3. Hello Harald, I’m interested in a download.

    Thanks,

    Jim

  4. Hi Jim, you got an offer by email. My general question as below:
    What is your planned IoT / M2M application?
    Do you have prior experience with wireless applications?
    What will be the estimated quantities in the first, second and third year of mass production?
    In which countries you would like to sell your product?
    When do you plan the start the development, to hold the first prototype in your hands and to pass the necessary certifications?
    Are you aware of the number and type of certifications you will need and their costs in your target terrtitories?
    Will the antenna be inside or outside the enclosure?
    What will be the size of the enclosure or the PCB inside the enclosure?
    What kind of supply voltage and source do you plan to use (AC, DC, battery inside with charger etc.)
    Do you need to outsource the development?

    Based on your answers to the above questions we will provide a hardware and software concept outline.

    For small quantities we prefer concepts utilising connector-based radio modules. For medium to large quantities we prefer SMT mounted radio modules. All components specified will be surface mount to save money and the time and cost of manual work.
    If your IoT / M2M device is to be a GPS tracking device then we will need further details. The hardware concepts to track an eagle, a truck, an expensive asset like oil on canvas or a dog are quite different.
    If you plan an embedded antenna on a PCB inside a small enclosure, then you will save a lot of money by designing the device around the antenna. The antenna is the key in any wireless application.

    Thank you for your time and thank you in advance for your detailed answers. The more detail you can provide, then the more detailed will be our recommendation.

  5. Harald,

    Love to cook ;), would love a copy of your cookbook….

    Best,

    Mitch

  6. Hi Mitch, cooking is really hobby. My IoT M2M Cookbook will explain you for to cook – step by step. The menues of the readers are amazing. You will find an offer in your inbox.

  7. Oscar Navarrete

    Hello Harald!

    I´m very interesed in your book for a project of my University. It seems very complete for the purpose I want to do.

  8. HI Harald,

    May I have a copy of the book? Appreciated.

    Zhixi

  9. Hi Harald,

    Could you kindly send me a copy of your book? Thanks a lot!

    Zhixi

  10. Hi Zhixi, you got an offer by email this morning.

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

  12. Hi Harald,
    Good day! I plan an IoT project shortly for Home Management. I’d like to read up your book and gain some knowledge.Thanks.
    Prakash

  13. Hi Harald, I would love a copy of your book. How can i get one?

    Thanks,
    Chris

  14. Hi Prakash, you will find an offer in your email inbox.

  15. Hi Chris, you got an offer including same answers on your questions.
    Regards
    Harald

  16. Muraleedharan P G

    A copy of the book is appreciated.

  17. Dear Muraleedharan, you will find an offer in your inbox.

  18. Hi Harald,

    Great IoT and M2M Posts.
    We have created an IoT Cloud Labs and MVP StartUP Foundry.
    Also teamed up with other Labs in EU/ASIA&Americas to crowd-source StartUP success.
    Would like to receive the link to download your IoT cookbook.

    E

  19. Hi Ed, thank you for the nice words. From time to time I write a short article. You will find an email with an offer in your inbox.

  20. Hi Harald, I would love a copy of your book. Thanks in advance.
    Javaid

  21. Hi Javaid, please be so kind and have a look in your inbox. You will find an offer. 😉

  22. Hi Sir,

    Will like to puchase the book…could you please tell the procedure for it.

  23. I’d love to get a copy too — thanks for writing this!

  24. Hi Arun, you got an email. I will come back with details in the evening.

  25. Hi Ken, you got an offer by email.

  26. Dear Herald,
    I think, I missed your mail, may be went to SPAM. Appreciate sending again.
    Br,

  27. Hello Harald,
    I would like to recieve a copy of the IOT cookbook.
    As a monitoring statiin we are busy to integrate different IoT devices with multiple functions en out of the standard.

    Thx and i hope to hear from you soon

    With regards,
    Peter Lenters

  28. Hi Peter, you will find an offer in your inbox. BTW, your office is just 3 hours by car from my home office. I had a look on your website. Just to let you know that I can help with some unique video based IoT solutions. Special solutions I offer case by case and most time not public by my blog.
    Regards from Lower Saxony
    Harald

  29. No problem at all. I will send it again. Just in case – my email is harald . naumann (at) gsm – modem . de

  30. Hi Harald,

    I would love to receive a copy of your book. How can i get one?

    Thanks,
    Omar

  31. You will find an offer in your inbox.

  32. Hello Harald,
    I would love to have a copy of your book. May i?
    Thanks,
    Jose

  33. Hi Jose, you will find an offer in your inbox.

  34. Hi Harald,

    I am new to this m2m world would like to read your book and try something out, can you please provide copy of it?

  35. Hi, I would greatly appreciate a book!! Want to dive in to help the environment 🙂

  36. Hi Harald,

    Please send me an offer for your book.

    Thanks,
    Barbara

  37. Hi Barbara, sorry for delay. I was outside the office to visit customers. You will find an offer in your inbox. If you like I can help later on with wireless modules and antennas as well.

  38. You will find an offer in your inbox.

  39. After reading the book you need some practice. If you like i can help with some components to design you first own IoT / M2M device.

  40. Hi Harald, Requesting you to share a copy of your cookbook for my academic interest and learning about IOT in a better way.

    Appreciate your efforts in explaining the concepts outlined above.

  41. Hi Krishna, you will find an offer in your inbox.

  42. Hi Herald,

    Love to read your IoT M2M cookbook.
    Please send me a copy.

    Thanks
    Bhasker

  43. Nagasai Panchakarla

    Hi Harald,

    I´m very interested in reading your book. May I?

    Thanks,
    Nagasai

  44. Yes, I am interested in a copy of your book for my IoT projects!
    Thanks

  45. Hello Harald
    Please send me links to your book.
    Shah Husain
    Canada

  46. Please allow me to download ebook.

    Shah Husain
    Canada

  47. Hi Harald,

    Please may I have a copy of your book? It sounds like a wonderful resource.

    Many thanks,

    Corey

  48. Hi Corey, you will find an offer in your inbox. If you like you can get more then just a book. For interesting projects I am open for consulting. In may daily job I am in the sales of wireless modules and antennas. If you like I will support you with my components as well.

  49. Hi Shah, you will find an offer in your inbox.

  50. Hi Hoang, you will find an offer in your inbox. If you like I can show you some wireless modules and antennas, which will fit to your application. Just drop an email to harald.naumann (at) gsm-modem.de

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