Have you ever noticed that the bars on your smartphone screen behave strangely? In one room, the phone shows a full signal, but if you take a step towards the window, the connection disappears. Visual indicators in the form of sticks are often misleading to users because manufacturers configure their display differently. To objectively assess the quality of the network, accurate numerical values are necessary.
Understanding the real signal level helps not only to find the best place to call, but also to diagnose problems with the modem or SIM card. In this article, we will analyze professional measurement methods that are hidden from the average user and learn how to interpret the data obtained without unnecessary technical magic.
Measurement accuracy is critical when setting up signal amplifiers or choosing an operator in a country house. Instead of guessing why the Internet is slowing down, you can operate with specific numbers and make informed decisions on optimizing communication.
Understanding signal units
Before running into the settings, you need to figure out what exactly we are measuring. The standard unit of measurement for radio signal power is decibel milliwatt (dBm). It is a logarithmic value and can be confusing for beginners due to its negative values.
The closer the dBm value is to zero, the stronger the signal. For example, -50 dBm means excellent reception, while -110 dBm indicates an extremely weak signal, close to losing the network. It is important to remember: minus one hundred is worse than minus fifty, although mathematically this seems illogical.
In addition to dBm, the Android system often uses the parameter ASU (Arbitrary Strength Unit). This is a relative value specific to Android and is directly converted to dBm depending on the network type (GSM, LTE, WCDMA). The conversion formula is different for different communication standards, which makes dBm a more universal indicator.
⚠️ Attention: Do not confuse signal strength (RSRP/RSSI) with signal quality (SINR). You can have a high power level (-60 dBm), but at the same time a low speed due to noise and interference on the air.
For quick reference, remember the following ranges of signal power values:
- 📶 From -50 to -70 dBm: Ideal signal, maximum data transfer rate.
- 📶 From -71 to -85 dBm: Good signal, stable operation of voice and Internet.
- 📶 From -86 to -100 dBm: Average signal, periodic speed drops are possible.
- 📶 From -101 to -120 dBm: Bad signal, calls may be interrupted, Internet is unstable.
Using the Android engineering menu
The fastest way to access technical information is to use the hidden engineering menu. This is a diagnostic tool built into the firmware that does not require the installation of third-party software. However, access to it may differ depending on the device manufacturer.
For most smartphones based on chipsets MediaTek and some Samsung a universal code is used. Open the Phone application (dialer) and enter the combination ##4636##. If the code is correct, the “Testing” menu will open in front of you.
In the list that opens, select “Phone Information”. Here you will see detailed statistics on the current connection. Find the line Signal strength (Signal Strength). This is where the current values in dBm and ASU are displayed in real time.
Code not working? What to do?
If the combination ##4636## does not work, the manufacturer may have blocked access to the engineering menu. Try the codes *#0011# (for Samsung) or install the Activity Launcher application to manually find the hidden system section "Testing".
It is worth considering that on modern versions of Android (starting from 10 and higher), access to some functions of the engineering menu may be limited by Google security policies. In such cases, the displayed information may be shortened, or the menu will not open at all.
☑️ Check in the engineering menu
Third-party applications for network monitoring
If the built-in tools do not provide a complete picture or the interface seems too complicated, specialized applications from Google Play come to the rescue. They not only show numbers, but also visualize data in the form of graphs and maps.
One of the most popular tools is Network Cell Info Lite. This application displays information in the form of a speedometer, which is very clear. It shows the signal strength for all available towers, not just the one you're connected to, which is useful when finding the best spot in the room.
Another powerful tool is G-NetTrack. This solution is closer to professional field tests. It allows you to log a signal over time, save routes linked to coverage level, and export data for in-depth analysis. The interface here is more strict and technical.
Logging and detailed analysis| Application | Main function | Complexity | Presence of advertising |
|---|---|---|---|
| Network Cell Info | Visualization and tower map | Low | Yes (in Lite version) |
| G-NetTrack | High | No | |
| OpenSignal | Speed tests and coverage map | Medium | Yes |
| CellMapper | Building maps of towers by users | Average | No |
When using such apps, it is important to provide them with all the necessary permissions, including access to geolocation and phone. Without this, they will not be able to read data from the device’s modem. Also note that constantly polling network sensors can increase battery consumption.
To obtain the most accurate data in applications like G-NetTrack, turn off Wi-Fi during measurements so that the phone does not switch between interfaces and distort cellular network statistics.
Deciphering LTE and 5G parameters
C With the advent of 4G and 5G technologies, the measurement system has become more complex. If in old 2G/3G networks we focused on the overall RSSI level, then in LTE the key parameter becomes RSRP (Reference Signal Received Power).
RSRP shows the average power of the useful signal received from the base station. This is the most accurate indicator of connection quality in fourth generation networks. RSRP values are usually in the range from -44 dBm (maximum) to -140 dBm (minimum).
Another important parameter is SINR (Signal to Interference plus Noise Ratio). It shows the ratio of useful signal to noise. Even with good RSRP, if the SINR is low (for example, below 0), the Internet speed will be low due to strong interference from neighboring towers or equipment.
⚠️ Attention: In 5G_NR networks, the parameters may be called SS-RSRP and SS-SINR. The principle of their interpretation is similar to LTE, but the threshold requirements may be stricter due to high frequencies.
Here is how you can interpret the RSRP values for LTE networks:
- 🚀 Above -80 dBm: Excellent quality, all network capabilities are available.
- 🚀 From -80 to -90 dBm: Good coverage, stable streaming and calls.
- 🚀 From -90 to -105 dBm: Borderline condition, speed may drop during peak hours.
- 🚀 Below -110 dBm: Critical zone, the phone may often lose the network or switch to 3G.
Factors affecting the accuracy of the measurement
The obtained numbers are not an absolute constant. The signal level is a dynamic value that changes every second. The readings are influenced by many external and internal factors that must be taken into account during diagnosis.
The materials of the walls of your home play a huge role. Reinforced concrete floors and energy-saving glass coated with metal can weaken the signal by 20-30 dBm. Therefore, measuring at the window and at the back of the room can give radically different results.
It is also worth taking into account the “body effect”. The human body contains a lot of water, which perfectly absorbs radio waves. If you hold the phone with your hand in the antenna area, the signal may drop several bars. For the purity of the experiment, place the device on a surface.
To obtain representative data, take measurements at different points of the room and at different times of the day, since the load on the operator’s base station directly affects the available speed and stability.
Don’t forget about the case. Metallic or overly thick protective cases can shield the smartphone's antennas, artificially reducing reception performance. Remove the case if you doubt the accuracy of the measurements.
What to do if the signal is poor
If the measurements showed values worse than -110 dBm, it’s time to act. First of all, try changing the network mode. Sometimes forced switching to 3G (WCDMA/GSM) gives a more stable voice signal than weak and unstable LTE.
Check your access point (APN) settings. Sometimes incorrect parameters can limit the speed even with a good signal. Reset the access point to factory settings in the mobile networks menu. It also makes sense to re-register online: turn on airplane mode for 10 seconds and turn it off.
In private homes, installing a signal repeater (amplifier) can be a solution to the problem. But before purchasing equipment, be sure to find out what frequency your operator operates on in a given area, using data from scanner applications. Setting the amplifier to the wrong frequency is useless.
⚠️ Attention: The use of uncertified signal amplifiers may interfere with the operation of operator base stations, which is a violation of the law. Use only certified equipment.
If all else fails, there may be a problem with the SIM card. Old cards that are more than 5-7 years old may have worn out contacts or may not support modern encryption standards. Replacing a SIM card in the operator's cabin often solves the problem of a “floating” signal.
Frequently asked questions (FAQ)
Why does the number of signal “sticks” not match the numbers in dBm?
Smartphone manufacturers independently calibrate the display scale. For one phone, -95 dBm may be two sticks, and for another - three. Numbers in dBm are always more accurate and more versatile than visual indicators.
Is it possible to improve the signal programmatically without external antennas?
It is impossible to radically improve physical reception programmatically. However, you can try resetting the network settings, updating the phone firmware, or manually selecting a tower with the best signal through the engineering menu (the function is not available everywhere).
What ASU value is considered normal for 4G?
For an LTE network, the ASU value usually varies from 0 to 97. A range from 30 to 60 ASU is considered a good indicator. Values below 10 indicate a very weak signal.
Does weather affect signal strength?
Yes, heavy rain, snow or thunderstorms can absorb and scatter radio waves, especially at high frequencies (4G/5G). This phenomenon is called atmospheric attenuation and can temporarily degrade performance by 5-10 dBm.
Why does the average user need to know the signal level?
This knowledge helps to understand whether the operator should be blamed for poor Internet or the problem is in the phone/premises itself. This saves time when contacting technical support and helps you choose the right place to install a landline phone or router.