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 Nagasai, you will find an offer in your inbox as well.

  2. Sreenivas Adiki

    Dear Mr. Herald

    I am interested in your book and want to have a copy of the same.

    I am trying to build a IOT practice and need help and information if possible on how to bootstrap this .

    Any help or guidance is of great help

    Thanks and Regards
    Sreeni

  3. Dear Sreeni, you will find an offer in your inbox. Parallel to the book I write short articles in my blog for everybody. Moreover I cab help with wireless modules and antennas as well.

  4. Herald,

    I would love to get a copy of your book and learn from your insights on M2M/IOT.

    Thanks!

    Nick Naumovich

  5. I am web developer and good exposure on javascript and completed masters in computer applications
    Currently. looking to explore the IOT. I need your help where should I start the basic things and move forward
    Can you please guide me

  6. What about to make a copy of the IoT button listed here:
    http://www.gsm-modem.de/M2M/m2m-apps/the-iot-button-fantasy-or-business/
    Step 1:
    Order a copy of my IoT M2M book http://www.gsm-modem.de/M2M/m2m_iot_cookbook/
    Step 2:
    Read it.
    Step 3:
    Read it again
    Step 4:
    Order the GSM module eval kit with me plus some GSM modulesample
    Step 5:
    Get the kit up and running and write some code to run on the module.
    Step 6:
    Make your first own PCB and load the code on the module

  7. Nick you will find an offer in your inbox. I which you and your team a Merry Christmas.

  8. Hello Harald,

    Please share the offer for the IOT Cookbook.

    Thank you
    Vikas Bodani

  9. Hi Harald, could you please let me know the price of this book and where I can this book? Thanks.

  10. Hi Sunil, I still charge Euro 90 for the PDF and I do not plan to charge more. I sell it direct because I prefer the difect contact to my book readers. A part of the book readers of the past placed later on orders for consulting, development or wireless modules / antennas.

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

  12. Hello sir, Please provide me purchase link & offer detail.

    regards,
    Vivek

  13. Hello Harald,

    I am in the final stages of developing a m2m product, and would love you read your book before I start production. Could be I missed something, and maybe some good points for you book.

    Could you provide me instructions on how to purchase the book?

    Best regards
    Nikolaj

  14. Hello Nikolaj,
    I just came back from kitchen to prepare the Sylvester dinner. Cooking is my hobby. This was one of the reasons to call my book the “IoT M2M Cookbook”. The books explains you the basics how the handle the ingredients. The guideline was a tracker on GSM and GPS. GSM can be replaced to UMTS/HSPA or LTE. By ignoring GPS you can a telemetric device.
    You will find an offer for the book in your in-box. Moreover I can help with the wireless modules and antennas later on as well.
    Thank you in advance for your order. I wish you and your family a Happy New Year 2016.
    Best regards from Germany to Denmark
    Harald

  15. Hi Vivek, you will find an offer in your inbox. I wish you and your family a Happy New Year 2016.
    Best regards
    Harald

  16. Hello Harald Naumann
    I really interested with your book. kindly provide your book offer details.
    Thank you very much
    Ghalib
    Oman

  17. Hi Ghalib, I wish you a Happy New Year. You will find an offer in your email inbox.
    Best regards
    Harald

  18. Can you send me a paypal link to buy a copy of your book? I’m interested in PCB antennas. I would like to know a little magic about PCB antenna Design before an RF design company dazzles me with their magic and a large bill.

    I currently have a product that needs an RF redesign before undergoing FCC and PTCRB certification. The current antennas are attached to the product. Because of the high cost of OTA certification, I have to move the antennas at least 20 cm away from the main unit. I have a total of 6 antennas. 4 x 3G antennas, 2 x LTE Antennas. I would like a PCB antenna solution mounted inside an external plastic case.

  19. Hi Todd,
    I wish you a Happy New Year 2016. You will find an email with Paypal Link in your inbox. The book describes how to make a copy of a GSM PCB antenna listed in the book. Trouble with FCC you can avoid with 20 cm distance between the antenna. The OTA is a part of PTCRB. If you quantity is sell than 10000 per year, then I assume nobody will care. Technical 6 antennas in one enclosuse is a challange. Take care on isolation between the antennnas. The make your idea real you will need a Vector Network Analyser as well. My VNA I got for Euro 3000. It is easy to learn how to use the VNA, because it is a PC based machine on USB.
    Thank you in advance for your order.
    Best regards
    Harald

  20. hi,Harald
    Could you share a copy of you book to me, I am from Mediatek work for m2m also,thanks very much.

    Regards,
    David duan

  21. Hi David, you got an offer yesterday. Please note that my ultra small GSM / GPS tracker is based on Mediatek chipsets. My IoT M2M Cookbook is neutral and does not name any brand names of GSM or GPS module manufacturers. However, based on the experience with your chip sets I can give my customers in IoT and M2M a much better support.

  22. Hello Harald

    I am very much interested in your IoT M2M Cookbook. Can you please share the book offer details.

    Regards
    Sanjay

  23. Hi Sajay, you will find an offer in your email inboox.
    Regards
    Harald

  24. Jürgen Ebenhan

    Hello Harald
    I am very much interested in your IoT M2M Cookbook. Can you please share the book offer details.
    Regards
    Ebenhan

  25. Hi Jürgen, thank you for your call and sorry for delay. For some reasons the whole world picked up the phone and gave me a call. You will find an offer in your in-box. You can pay by Paypal or by wiring to my bank account. BTW, will ee meet each other at Embedded World hall 5 / stand 5-139? I will stay all days and plan to leave on Friday after lunch. I also will come back with a 2400 MHz ceramic patch antenna. I will show you the mechanical dimensions. If you like it, then I will help with samples. You can tune the patch antennas yourself or I can tune it for you. Have a nice weekend.
    Regards
    Harald

  26. want to get a copy of your book.

  27. Hi Harald Naumann,
    Please kindly send me your book offer details.
    Thanks
    Horace

  28. Hello Mr. Harald,

    I am nterested in your IoT M2M Cookbook. Request you please share the book offer details.

    Regards,
    Jatinder Arora

  29. Hi Jatinder, you will find an offer in your in-box. A lot of book readers placed orders for consulting, development, wireless modules or antennas after reading to book. They integrate me at product specification in an early phase often. It is not just selling the book – its a personal relationship with book readers later on. This is one of the reasons why I do not plan a version on Amazon. I will be glad if you will be a customer of the book and may further services and wireless components as well.
    Regards
    Harald

  30. Hi Hoarce, you will find an offer in your in-box. I will be glad id you will be a customer for consulting, development, wireless modules or antennas later on as ewell.
    Regards
    Harald

  31. Hi Abhishek, you will and offer in your email in-box. Do not hesitate to contact me for further services and components (e.g. wireless modules or antennas) later on as well.
    Regards
    Harald

  32. Dear Mr Naumann,

    I work in the point of sale indostry, and I’m very interested in reading your IoT M2M Cookbook.

    Best regards,

    Jose

  33. Hi Jose, you will find an offer in your email in-box. If you like I can help later on with wireless modules or embedded antennas as well. Thank you in advance for your order.
    Regards
    Harald

  34. Hi Mr. Naumann,

    Please kindly send me your book offer details.

    Thanks
    Flávio

  35. Hi Flavio, you will find an offer in your inbox. If you like we can meet next week an “embedded world” in Nuermberg at hall 5 booth 5-139. I will stay all tree days. If you can´t make it then I will be glad to make you a proposal for wireless modules and antennas by email, Skype or phone.
    Best regards
    Harald

  36. very interested to get the copy of the book.
    Regards,
    veljko@selmet.com

  37. I would like to read your book. Please tell me how to obtain it. Thanks!

  38. Hi Robert, you will find an offer in your inbox. Next week I will stay at embedded world in Nuermberg at hall 5 stand 5-139. May we can meet each other.

  39. Hi Veljko, you will find an offer in your inbox. Next week I will stay at embedded world in Nuermberg at hall 5 stand 5-139. May we can meet each other.

  40. I will really want to get this book.how do i go about it?

  41. Dear Akawo, You got an offer by email as well.

  42. Hello Harald

    I am interested in your IoT M2M Cookbook.

    Can you please share the book offer details.

    Best Regards

  43. You will find an offer in your email inbox.

  44. Hello Harald –
    I also am interested in your IoT M2M cookbook
    Regards

  45. Hi Duer, you I will come back with an offer to you. I had a look on your website. You application looks very interesting. If you like you can source the wireless modules and antennas from me as well.

  46. Thank you sir for your endeavors to reach a larger audience on how to develop reliable communications equipment. I like to get your offer. Thank you. I love Germans if you are from there

  47. Hi Felix, you will find an offer in your in-box. Yes I am from Germany and I give just back what I got more than 20 years ago. My boss educated me and answered all my questions. Today it is much easier to share experience and knowledge. I selected to write a book in PDF and to sell it all over the world. I will not get rich by incoming money, but rich by contacts to engineers all over the world. Some of the book readers placed orders for consulting later omn or bought the wireless modules and antennas from me.
    I will be glad if you will be a reader of my book as well.

  48. Hi Mr. Naumann,

    I would like to know more about building reliable and cost-effective Iot/M2m devices. Please send me info on how to get a copy of your book. Best regards.

  49. Hello Harald,
    I am highly interested in your IoT M2M Cookbook.
    Now I am thinking of a potential IOT idea and needing some technical assistant, your appeareance is just on time.

    Regards,
    Tiger

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