1. General questions

1.1 What is NetMetr?

NetMetr serves for thorough testing of your connection to the Internet over cellular networks and Wi-Fi.

NetMetr offers:

• Mobile connection detailed testing
• The display of test results on the map with the possibility of filtering according to various parameters
• The measurement result statistics in networks of all operators
• Ability to synchronize the results of tests of various equipment and their common display
• History of your tests
• The data obtained from the measurement and the application source codes are published as OpenData and OpenSource

1.2 Who is the author of NetMetr?

NetMetr is based on the source code of RTR-NetTest (netztest.at), which is an open source tool from the Austrian Regulatory Authority for Broadcasting and Telecommunications (RTR).

NetMetr itself is developed by CZ.NIC and the source code is available here.

1.3 Why should I test my connection?

Bandwidth is an important quality parameter for your mobile Internet connection. NetMetr offers you the opportunity to check the current bandwidth. Another possibility is to compare the test results with those of other users. On the Android system it supports network analysis, provides a more detailed test tool for network diagnostics (NDT). The test results carried out by all operators in various places may be of interest to a large number of users.

1.4 What is being tested?

Pomocí NetMetru můžete ve svém mobilním zařízení otestovat:

• download speed,
• upload speed,
• connection latency (ping),
• signal strength, if the device allows it

The additional test (NDT), which is available on Android devices, can test also other quality parameters, such as packet loss.

1.5 How to contact us?

You can contact Technical support, mainly with the questions for which you have not found the answer here. Please send your questions to netmetr@labs.nic.cz.

1.6 What types of connections can be tested?

NetMetr is available for mobile devices running on Android and iOS (Apple). You can test both over cellular networks (EDGE, UMTS, LTE) and Wi-Fi.

In case of computers or mobile devices with an unsupported operating system, you can use the Web version of the test, functional in all modern web browsers.

1.7 How to contact technical support if I have a problem with NetMetr?

Before contacting technical support please try first to find an answer to your question in this FAQ. If you don’t find the answer, we would be happy if you write us to netmetr@labs.nic.cz.

1.8 What is the difference between NetMetr and other applications for measuring the speed of the connection?

NetMetr offers:

• independent and non-commercial solution
• metering server connected through a fast and high capacity connection to NIX.CZ
• detailed analysis of the connection using NDT test
• open data – data, obtained from measurements, are available to the public for further analysis as Open Data

2. Technology

2.1 How does NetMetr work?

NetMetr measures the qualitative parameters of your wireless Internet connection by testing transmissions from your mobile device to the server and vice versa. Actual values ​​of connection parameters ​​are calculated from the measured values. A complete description of the test methodology is available here.

NetMetr can perform two different tests:

• The basic test is a quick analysis of download and upload speed, latency (ping), and - for Android - signal strength.
• Detailed test (NDT test) is an additional independent test of the M-Lab association, using specific diagnostic options in Android system.
• In addition, in Android also Quality of Service properties are tested. (changes of content, reference page, transparency of connection, DNS, TCP and UDP ports).

2.2 What does the NDT test do?

After performing the quick baseline test of your connection you can run the additional test for complex network analysis. The Network Diagnostic Tool (NDT) is used, from M-Lab association (http://www.measurementlab.net).IOS (iPhone, iPad) does not support this test, unfortunately.

Systém iOS (iPhone, iPad) provádění tohoto testu bohužel neumožňuje.

2.3 What are the benefits of complementary NDT test?

This more detailed test verifies the amount of network parameters that are necessary for a comprehensive analysis of your connection and are not tested by the basic test. A list of all network parameters and details of the NDT test can be found on the M-Lab web.

2.4 How is my Internet connection tested?

NetMetr measures the connection from your device to the test server. This server is connected by a fast and high capacity connection directly to the Internet NIX node, thereby minimizing the effect of the data transport speed on the servers of your mobile operator.

2.5 What should you pay attention to before running the test?

To obtain the least distorted test results you must meet several conditions:

• There are no data intensive applications running in the background on your device.
• The device is as close to a Wi-Fi AP as possible to avoid distorting the test with a weak signal (when measuring connectivity via Wi-Fi)
• You did not run over your FUP and the operator did not reduce the speed of your data connection (when measuring mobile data connection)

2.6 Is the source code available?

NetMetr is an open source, the source code of the server part is available at https://gitlab.nic.cz/labs/netmetr, the mobile apps at https://gitlab.nic.cz/mobile/netmetr_flutter.

2.7 What connection speed do I need?

For some applications a large bandwidth is not required. For normal surfing, 2 Mb/s are usually quite sufficient. However, some applications do not work properly without sufficient bandwidth. For example, online video and music can be operated without interruption only if the connection is fast enough.

It is important to take into account not only the bandwidth towards the user (download), but also towards the Internet (upload).

2.8 What factors influence the test result?

• Maximum bandwidth of mobile connection to the Internet (speed limit depending on the tariff plan)
• Bandwidth provided by your internet provider, its utilization
• The device on which the test is conducted
• Operating system of the device and its configuration

When using Wi-Fi:

• The distance between the Wi-Fi router and your device
• Quality of Wi-Fi router and the supported technology (eg. 802.11n or 802.11ac)

When using a mobile connection: - The technology used (EDGE, UMTS, LTE) - Quality of service at the point of measurement (signal strength, depending on the device) - Whether you are inside or outside the building, - How fast you are moving (in a moving car, on a highway or in a train, you will have a lower bit rate) - The number of users simultaneously sharing the base station (BTS)

2.9 What is the optimal day time for the test?

The test result is inter alia influenced by the day time. It is therefore recommended to perform a test at regular intervals and at different times of the day. The use of Internet, depending on the day time, can be estimated by use of the connection to the main Czech Internet NIX node.

2.10 What is the influence of my Wi-Fi router or access point on the measurement?

Wi-Fi router or AP can have a huge impact on the speed of connection.

If your router is unable to utilize the full capacity of your Internet connection, it will affect the test results. For high-speed connectivity it is always advisable to use a router that supports IEEE 802.11n or 802.11ac, of course only if the connected devices support these standards.

It is also important that the router can perform Network Address Translation (NAT) with sufficiently high throughput. Also, the distance between the router and your device should not be too big.

If the test result is fundamentally different from the expected values, we recommend checking the wireless router.

2.11 How many tests need to be done to get really reliable values?

The test result depends on several factors: day time, network usage and your location. You can increase the predictive value of your test results by rerunning them at different times and different places. The more tests you run, the better basis for an objective assessment of your connection you get.

2.12 How often can I repeat testing with NetMetr?

The NetMetr test can be repeated as often as you want. For example, in mobile applications the test can be repeated immediately after its completion, just click on the "New test".

Before repeating it is necessary to complete the detailed test (NDT applicable only for Android).

The test generates a transfer of large volumes of data - if you test over cellular networks, you can exceed your FUP limits and a subsequent speed reduction by the operator can happen.

Regular tests will improve the results accuracy.

2.13 What are the volumes of data transmitted in the test?

The amount of transmitted data varies depending on the bandwidth of the Internet connection. NetMetr tests the download and upload capacity of your Internet connection for about 20 seconds, with the fastest available speed. Depending on the available bandwidth of the connection it may result in an increased utilization of data.

• When measuring via GPRS the test transfers approx. 130 kB data, over HSDPA the test is essentially more data demanding, it consumes over 14 MB of data.
• With a very fast internet connection NetMetr uses very large amounts of data, on a symmetrical 100 Mb/s connection it consumes a data volume of approx. 250 megabytes
• If you carry out more detailed testing using NDT test data volume will increase approximately 2.5 times.

Please note that the data transmission can cause an exhaustion of the FUP when measuring a connection via the cellular network, depending on your tariff plan.

2.14 What version of IP protocol is used?

By default, the application uses IPv6, if available. If not available, the IPv4 is used. You can disable IPv6 in the application (the "Options").

For more information about IPv6, visit the Wikipedia article on IPv6.

3. The results of the tests

3.1 What “download” means?

Download is a download of data from the Internet to your device. The unit “Mbit/s” is the number of megabits per second.

Data speed, advertised by Internet service providers, usually means an “absolute” data speed, incorporating also the transmission of other data, due to the overhead network protocol used. NetMetr however measures the “real” connection speeds. These values ​​are on average about 10% lower than the absolute transmission speed of your Internet connection.

3.2 What “upload” means?

Upload means the transfer of data from your device to the Internet. Upload speeds normally do not appear in marketing materials and are usually much lower than the download speed. But for fast access to the internet it has similar importance as download speeds, because the communication on the Internet is carried out practically always bidirectionally. Speed ​​of data upload is especially important if you want to send photos, use technology to share files or use video calls.

As with download, there is a difference between "absolute" and "real" data transfer rate here too.

3.3 What is the latency (ping)?

Latency (ping) indicates the server's response time - the time it takes to transfer small amounts of data from your device to the server and back. It is measured in milliseconds (ms). Latency is very important not only for playing online games, but even for completely normal surfing high latency has significant impact on user comfort. This delay is significantly affected by the technology used for your Internet connection, as well as its use (eg. how many users are currently connected simultaneously).

Fast connections to the Internet have a latency typically less than 2 ms (fast copper networks and fiber networks), slow connections can have a latency of more than 500 ms (GSM); typical values are in the range from 10 to 50 ms. Of course it depends on how the server is connected. If you are connecting to a remote server, the length of the transmission connection has also a significant impact on latency (eg. for Japan it may be from Europe about 280 ms even on fast connections.).

3.4 What is the strength of the signal?

The stronger the signal that your device receives from the base station (or access point of Wi-Fi), the faster and more stable internet connection you can expect. If your cell phone is outdoor or near an open window, the signal is usually better than indoors. In case of connection via Wi-Fi, it is important that as few obstacles as possible shadow to signal (eg. walls) between Wi-Fi access point and the device (eg. tablet).

3.5 How to read the signal strength?

Signal strength (in dBm) is measured in negative numbers. The higher the measured value is (closer to zero), the stronger the signal. For example, the value of -50 dBm is a very good signal, the value of -113 dBm indicates the GSM / UMTS signal is very weak.

3.6 How do I know if the test result is good or bad?

Color of the icon (red/yellow/green) varies by the values of data speed signals:

• Green: The value is 10 Mb/s or higher (download), respectively 2 Mb/s or higer (upload)
• Yellow: The value is between 2 and 10 Mb/s (download), respectively between 1 a 2 Mb/s (upload)
• Red: The value is lower than 2 Mb/s (download), respectively lower than 1 Mb/s (upload)

This color range is displayed regardless of the type the connection and corresponds solely to the measured velocities. Very high speeds can be achieved only through certain technologies such as HSPA + or LTE. Therefore, a red icon at the result does not necessarily mean a bad result, if in a testing area is available only 2G network.

For ping, the icon color varies by the network latency:

• Green: The value is 25 ms or lower
• Yellow: The value is between 25 and 75 ms
• Red: The value is 75 ms or higher

3.7 How to properly interpret test results?

The measurement result shows a snapshot of the quality of your Internet access. If test results are lower than those advertised by the operator, it does not necessarily mean that operator fails to comply with terms and conditions.

The network connection may be affected by various technological factors as the number of other users who are simultaneously connected to the same base station of mobile networks, quality of Wi-Fi router, system configuration, etc.

In any case you can reach really reliable results only if you frequently repeat measurements while you consider possible systematic and random measurement errors.

3.8 What is the unit Mb/s?

Data connection speed is usually given in Mb/s (eg. 8 Mb/s), which stands for megabits per second. Following conversions are used:

• 1 Mb/s = 1000 kbit/s
• 1 kbit/s = 1000 b/s

In addition to using the unit b/s it is customary to use also byte/s (B/s, e.g. information about the download speed in Internet browsers): Since 1 byte/sec = 8 b/s, the speed Internet connection can be described as 8 Mb/s, 8000 kbit/s or 1 MB/s.

Download of 3 MB file on 8 Mb/s connection will take about 3 seconds.

3.9 Is there any operator ranking by speed?

It is not the purpose of the application NetMetr to rank operators, but rather to provide users with comprehensive information on the quality of their Internet connection. Statistics from all the test results, broken down by operators, can be found the Stats page or divided by individual months on the web page Monthly results.

When assessing the operators offers please keep always in mind that declared values ​​are usually the maximum theoretically possible, and that the real bandwidth is often much lower.

3.10 MCan I run the test, although the NDT test is not finished yet?

No, the two tests cannot be performed simultaneously.

3.11 Can a bad test result be caused by exceeding the monthly limit of the volume of transferred data (FUP)?

Yes, this is a very common problem. FUP, limit of the volume of data transferred, applies within the vast majority of mobile tariffs. After a certain amount of data transferred (both directions) operator reduces the speed of the connection. This limit varies depending on your operator and your tariff.

In the case that this restriction is applied by your operator, it will naturally have a negative influence on the measured speed value.

3.12 What is the synchronization code?

Test results from a variety of devices can be synchronized to have summary from other connected devices in each of the applications. For this purpose, the user must obtain the synchronization code from the NetMetr application and enter it in the appropriate devices.

Synchronization code can be entered (and display the results) also on the My measurements page.

3.13 I have problems with the measurements of signal strength

Some devices may display incorrect or outdated signal strength of the cellular network (it was observed in some Samsung Galaxy S2 phones, among others). In such cases the measurement of signal strength is not displayed in the application.

3.14 What is QoS?

QoS stands for Quality of Service. It is a set of rules how to set for certain data the maximum / minimum transmission speed, to prefer some traffic, and the like. More on Wikipedia.

4. The map

4.1 What results are displayed on the map?

The map displays the measurement results of the standard test, whereas the more detailed test results of optional NDT are not on the map, but are only available as tabular data. Map, in the mobile application or in the browser, offers a possibility by means of filters to select which specific data will be displayed on the map.

4.2 Does the map show the results of measurements performed outside the Czech Republic?

Yes, the results appear from around the world. Measurement is not geographically limited.

4.3 What is a percentile and a median?

The percentile is a statistical indicator describing value, below which fall X % of all measured values. For example, the 20% percentile is the value below which fall 20% of all test results.

The median is the 50% percentile, so it is a value that divides all measured values ​​into two equal sets. In other words, there is the same number of measurements with a value less as well as with a value larger than the median.

4.4 How exactly are placed locations with measured values?

Localization measurement is performed during the measurement depending on the capabilities and settings of your device and using

• GPS,
• Information from the network (Wi-Fi or cellular)
• Or by IP address

Localization with GPS is the most exact way, while using a mobile network we only get the approximate information on location. Determining position using an IP address is often highly inaccurate.

Measurements with an accuracy of less than 2 km are not displayed on the map. Measurements with an accuracy of less than 10 km are not presented in detail. We therefore recommend before measuring to activate GPS (if available).

Data on the accuracy of specific measurements are available as part of the open data.

5. Application for Mobile Devices

5.1 What permissions are required by the NetMetr application?

When installing the application, it requires the following permissions:

• Location - approximate location (by means of network) or precise location (by means GPS and network), it allows for example to locate the test result on the map
• Photos / media / files - this permission is required to store maps into memory
• Hardware controls - to prevent the device from going into sleep mode - measurement could be distorted if the device goes into sleep mode during the test
• Information about Wi-Fi connectivity

5.2 Which operating systems are supported?

Android and Apple iOS. On unsupported operating systems you can use the web test.

5.3 Which versions of Android are supported?

Android version 4.0.3 and higher.

5.4 Which versions of iOS are supported?

IOS version 7 and higher.

5.5 What is important to know before using?

• If you have a tariff plan with a limit for the volume of traffic (ie. FUP), use NetMetr for measuring cellular connection carefully. Within one test a relatively high volume of data is transmitted (actual volume depends primarily on the type of connection). This problem of measurement is usually not relevant when connected to a WiFi network.
• Certain factors (such as time of day, position inside / outside buildings, signal strength, etc.), have big impact on the test result in mobile networks
• After exceeding monthly data limit the mobile operator will reduce the speed of the connection. This obviously affects the test results.

5.6 Is it possible to use NetMetr on tablets?

NetMetr works on tablets and is optimized for them.

5.7 How to install Android application?

You can find NetMetr on Google Play.

5.8 How to install iOS app?

You can find NetMetr on Apple AppStore.

6. Web test

6.1 Which browsers are supported?

Web NetMetr test works on all versions of major browsers supported by their manufacturers. To perform the test it is necessary to have functional support of the Web Sockets technology. An overview of supported browser versions can be found on Wikipedia:

• Google Chrome,
• Mozilla Firefox,
• MS Internet Explorer.

6.2 What aspects does the web test measure?

Just download, upload and ping.

Advanced measurements of QoS and network parameters by NDT test is available only on the Android application.

6.3 Do you need to install some plugins to browser?

You do not. You need only a modern browser with Web Sockets support.

6.4 Why the browser asks for my location in the beginning of the test?

The test results, when location is detected with sufficient accuracy, are shown on the map. If you don’t want to publish your location, you don’t have to - the test result is not affected.

Determining the location without the GPS may not be very accurate, results with big uncertainty are not displayed on the map.

6.5 Is it possible to display the results of my web and mobile test together?

Yes it is. You should generate the synchronization code on the application on the mobile device and enter it on the My measurement page. Then you can find the tests from your mobile application in the table.