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

Add a Comment
  1. Hello Harald

    I am interested in your book, how do i proceed to get access it.

    Thanks
    Gordon

  2. Hi Harald,
    I am interested in your book. How do I download it? Thanks
    BJ Raval

  3. Dear Bj you the link and the password after paying the proforma invoice.

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  6. I’m interested in your cookbook. How n where to download it ?

  7. Hi ,

    I am interested in ordering a pdf copy of your book.
    Please advice me the next step.

    Thank you .

  8. Sahin, you will get an email.

  9. Welson, you get a link and password after placing an order and money on my account. You can pay by Paypal, debiting of your credit card by Paypal or wiring to my bank account.

  10. Hi Harald,

    I am interested ordering copy of your book, please advise how to proceed.

  11. Hi

    Suggest the cost for Cookbook PDF file and ways for payment.
    I am interested in PCB Antenna for GSM.

    Thanks
    Pavan

  12. Hi Pavan, you got an offer by email. The price is still Euro 90 and I do not plan to rise it.
    BTW, today I published “Can a magician reveal the magic tricks?”
    As many already know, I am interested in antennas. My great interest is integrated antennas. Such antennas can be found in gateways for electricity meters, but also in portable point of sale systems. Even permanently installed telematics devices use integrated antennas. For many developers integrated antennas are still magic.
    Is it allowed to reveal some magic tricks of the antennas?
    The advantages of integrated antennas are varied – Read more:
    http://www.gsm-modem.de/M2M/m2m-faq/can-a-magician-reveal-the-magic-tricks/

  13. Hi Sahputra, you have an email in your inbox.

  14. I am interested in purchasing your book.
    Thanks.

  15. Hi Erik, you got an email. Just to let you know, that I can help with wireless modules as well.

  16. Thanks for your work. I am interested in purchasing the book.

  17. Hi Fred, you got an offer. However, I am interested to offer wireless modules and antennas as well. BTW, my new VNA is a Dutch product.

  18. Hi Harald,
    I’m also interested.
    Thanks

    Yuli

  19. abdelilah oufdir

    HI Harald,
    I’m interested in your book , please send it to me .
    Thanks

    Abdelilah OUFDIR

  20. Dear Abdelilah, you will find an offer in your email inbox.

  21. Hi Juli, you will find an offfer in your inbox as well.

  22. Im interested in your book. kindly mail me payment procedures.

  23. Hi Shareef, you will find an offer in your inbox. If you have a wireless IoT M2M project, then my proposal is to read in first step the book. In parallel I can help with the wireless modules and an antenna concept. Even the the power supply or battery you can discuss with me.

  24. Sir, I am doing a project on dual band microstrip antenna using ansoft hfss. I’m having problem in the simulation frequency of 5.1Ghz. Could you please help me in some way?

  25. Shital, sorry I can not help. I have no access to Ansoft HFSS.

  26. Hi Harald,
    I am interested in your book. please let me know how to purchase your book.
    Thank you.

  27. I would like to purchase a book as well.

  28. Milky, you got an email with an offer. If you help with project details, then I can help with a propsal for wireless modules and antennas as well.

  29. Hi Charles, you got an email with an offer. If you help with project details, then I can help with a propsal for wireless modules and antennas as well.

  30. Hello Harald,

    I’m also interested in your IoT M2M Cookbook.
    Can you send me an offer and instructions on how to purchase?

    Thank you

  31. Hi Gosse, sorry for delay. I was traveling the whole week. You will find an offer in your inbox. You can pay by PayPal or by wire to my bank account. PayPal gives you the freedom to use your credit card as well.
    However, if you help me with a project desciption and forecast, then I can help with a propsal for wireless modules and antennas as well.

  32. Antonio de Castro

    Can I get a quote?

  33. Hi Antonio, you wil find an email in your inbox next minutes.

  34. ArunKumar Jayaprakasam

    Can i get a quote…

  35. Hi,
    Please share details for purchasing the book?

  36. Hi Anup, you will find an offer in your inbox. If you help me with project details, then I will help with a proposal for the wireless modules and the antennas as well.

  37. Hi ArunKumar, you will find an offer in your inbox too. If you like I can support your project with wireless modules and antennas as well

  38. I would like to buy a copy of the book? Paypal?

  39. Hi Craig, Paypal is fine. You will find an email in your inbox.

  40. Hello,

    I am interested in book, how can i get it?

    Thank you

  41. Hi Gark,
    You got an offer by email:
    Parallel to the book I can offer:
    – Wireless modules and antennas
    – Free of charge design review on schematic diagrams of 2G, 3G, 4G and GNSS customers
    – Customised antennas without NRE costs – by 10K order
    – Consulting and tips for hardware concepts
    My email adr is harald. naumann (at) gsm-modem.de

  42. Atul Salgaonkar

    Please send me details about purchasing your book; I will probably use PayPal.

    Thanks
    Atul

  43. Hi Atul, you will find an offer in your inbox. If you help with a project description, then I can help with a proposal for modules and antennas as well. If you project is 10K or bigger then I can help with customised antennas without NRE costs. If necsasary, I can help with consulting, antenna tuning, antenna developmemt, development of prototypes up to mass production, moulds for your plastic encosures and a lot of more.
    Thank you in advance for your order.
    Regards
    Harald

  44. Hi Harald,
    I would like to purchase your book. I’d also like to learn more about your consulting services for a project I’ve got going.
    Thanks
    /Bruce

  45. Hi Bruce, you will find an offer in your email inbox.
    My general project question are listed here: http://www.gsm-modem.de/M2M/thank-you/

    Parallel to the book I can offer:
    – Wireless modules and antennas
    – Option for free of charge design review on schematic diagrams of 2G, 3G, 4G and GNSS customers
    – Customised antennas without NRE costs – by 10K order
    – Consulting and tips for your hardware concept
    If I run out of time, then business partners often jump in. Usually I am able to make everybody happy. Just offfer some more details by email to harald.naumann (at) gsm-modem.de

  46. Could you please send me a quote for your book.
    In addition to that, could you please let me know what is the Certification (PTCRB like) less expensive accepted for other carriers?

  47. Efren, you will find an offer in your email inbox.
    PTCRB is a carrier certification in US. Just have a look in their database and you will detect a lot of laptops, tablets and smartphones are listed but only a few of M2M devices. There are much more M2M devices on US market than listed devices in PTCRB database. If possible, then bypass PTCRB.
    In US you have to follow FCC and in EU you have to follow R%TTE (CE). Both are government regulation. Which paerts of FCC or CE you have to pass you have to discuss with your local office for certifications. My IoT M2M Cookbook shows examples how to bypass for example the expensive SAR approvels. However, there is never only one and final answer. I handle the IoT M2M products of my customers case by case and give advice how to save costs for certifications, HW / SW deveopment, hardware concepts and a lot of more.
    I look forward to welcoming you to the community of customers who have saved time and money with the book. I hope that you will enjoy reading it.

  48. How to buy a pdf copy? Thx

  49. I am interested in purchasing your book, please let me know how I do this.

    Thanks,

  50. Hi Paul, you will find an offer in your inbox. Many thanks in advance for your order. Please note that I can help with a selection of wireless modules and antennas as well. On top you can ask for development of prototypes up to designs for mass production.

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