Divesoft ECHO User Manual

User manual

ECHO Analyzer

version 2025/08/08

#0000 Divesoft ECHO Analyzer

Safety warning

This analyzer is designed for measuring the content of oxygen and helium in an air-oxygen-helium gas mixture and possible carbon monoxide contamination. It cannot be used to analyze mixes containing other gases, including, for instance, mixes prepared using anything but pure gases or mixes in which air has been replaced with pure nitrogen (without atmospheric argon). The physical and chemical principles of the sensors used do not guarantee that the sensors will be selectively sensitive to a specific gas (oxygen, helium); there are a number of gases to which the sensors respond. Therefore, the gas composition shown by the analyzer does not mean by itself that the real composition of the mix is equal to the displayed values. The displayed mix composition is invalid unless the mixing technology ensures that there are no other gases present in the mix except air, pure oxygen and pure helium. The analyzer is not a certified measuring instrument. The results of measuring are only informative and it is not possible to use such results where a certified measuring instrument is required. When analyzing mixes in situations where the incorrect composition of the mixes could cause material damage, injury to health or threaten human health or life, for example in the case of breathing mixes for diving, the results of the analysis may not be used as confirmation of the correct mix composition. In these cases, the analyzer can only be used as an aid for increasing the probability that such incorrect mix composition will be detected before its use. The correctness of the mix composition must be established by the technology used to prepare it. The correct preparation of breathing mixes for diving (nitrox – oxygen-enriched air, trimix – a mixture of air, oxygen and helium, heliox – a mixture of oxygen and helium) requires special knowledge and experience which is possible to gain, for example, through an appropriate course. A failure to apply such knowledge can lead to an incorrect mix, even though the results of the analysis are seemingly correct. Such a situation can also be the result of a failure to take into account the influence of temperature and compressibility, an insufficient blending of the mix and other factors. Please remember that the analyzer can be broken or damaged and that the oxygen sensor is by its nature subject to ageing and thus its properties deteriorate. Therefore always verify the measured data in another way, such as by precise preparation of the mix, another analytical method, etc. In addition, the measured value must be subject to critical assessment using a common-sense approach and if it differs from the allowable variation of mixing accuracy, it must be considered invalid.

01. About firmware and hardware versions

The He/O2 analyzer is equipped with a microprocessor whose program (firmware) is continuously updated. This manual is for the initial firmware release 1.6.3, but the manual can be applied to any hardware version.

02. Measuring principle

The described measuring principle is valid only for mixes of air, oxygen and helium.

An electrochemical sensor is used to determine the oxygen content. The voltage at the sensor’s output is proportional to the oxygen content in the analyzed mix. The sensor has a limited service life and the proportionality of the dependence of voltage on the oxygen content changes over time; therefore, it has to be regularly calibrated. It is possible to choose between single-point, two-point and three-point calibration. Single-point calibration is fast, especially if air is chosen as the calibrating mix. For greater accuracy of the measurement, two-point calibration is used with two different mixes, typically air and pure oxygen. For strongly hypoxic mixes, i.e. mixes containing less than approximately 15% oxygen, three-point calibration is recommended. In this case, the third calibration gas should be a gas with zero oxygen content, i.e. pure helium or argon.

Helium content is determined on the basis of measuring the speed of sound in the analyzed mix. The speed of sound depends on the content of helium and oxygen, and the temperature of the mix. The dependence of the speed of sound on pressure is small and can be disregarded under normal atmospheric pressure.

At 0º C the speed of sound is approximately 970 m/s in pure helium, 330 m/s in air and 315 m/s in pure oxygen. Raising the temperature by one degree increases the speed of sound by 0.175 %. The speed of sound in the mix is described by a non-linear function of temperature, oxygen content and helium content.

The content of helium is determined by measuring the speed of sound, temperature of the mix and the content of oxygen. When measuring the concentration of helium, it is therefore necessary to have the oxygen sensor correctly calibrated or to know the oxygen content and enter it into the instrument.

The speed of sound is measured directly as the time it takes for an acoustic impulse to travel between two microphones. This measurement is performed alternately in both directions to make it possible to eliminate the influence of the gas flow-rate in the probe on the calculation. The acoustic impulses are heard as weak “clicks” from the probe in the helium-measuring mode.

Gas is delivered to the analyzer from a sampler connected to the compressed-gas tank and the gas flow is controlled using a nozzle to provide the volume needed for the analysis.

03. Analyzer control

ECHO has a single multifunction button. Switching on/off and control is done by long or short press of this button.

SWITCH ON
Long press of the button (3s)

CALL MENU
Long press of the button

MENU SCROLLING
Short button press

POSITION SELECTION
Long press of the button

LEAVE MENU
Short press to scroll to Quit and confirm with a long press

SWITCH OFF
Enter menu (long press) Select Switch off (long press)

04. Connection to mobile app

Divesoft.app

The mobile application is available for smartphones running Android and Apple iOS operating systems.

Download the mobile app
https://www.divesoft.com/en/app

Pairing indication
Bluetooth symbol flashes - ECHO is not paired with the app - searching
Bluetooth symbol stable - ECHO is connected to the device

Pairing
1. Switch on ECHO
2. Turn on the mobile app in Analyzer mode
3. The app will offer you the available Bluetooth analyzers. If it doesn't, press the three dots on the top right
4. Select ECHO from the list
5. A context menu will pop up in the app - press Pair
6. The ECHO analyser will show you the PIN. Enter this in the box currently offered in the app.

Troubleshooting Pairing Issues
If the mobile application does not display an option to pair with the ECHO analyzer, even though the Bluetooth icon is flashing on the device display, the analyzer may already be paired with another mobile device.

In this case, the existing pairing must be removed directly on the ECHO analyzer by following the steps below:
1. Press and hold to open the device menu.
2. Use short presses to scroll down to Setup.
3. Press and hold to select Setup.
4. Press and hold to select Bluetooth.
5. Use short presses to scroll to Erase pair, then press and hold to select it.
6. Press and hold to confirm deletion of the pairing, or short press to cancel the action.

05. Calibration of the oxygen sensor

The oxygen sensor’s properties change over time and it is therefore necessary to recalibrate it. We recommend that such calibration be performed at least once a month. ECHO analyzer has a built-in barometer sensor, which corrects itself. If you require the most precise results, calibrate the sensor before each measuring.

Calibration of the sensor is performed as either single-point or two-point or three-point.

During single-point calibration, the content of oxygen in air, which is known and constant (20.95 %), is measured by the sensor. The calibration constant of the sensor is set so that the instrument displays 21.0 % (after rounding).

Two-point calibration proceeds in the same manner as single-point calibration, but uses two calibration gases – pure oxygen and air. Two-point calibration is more arduous as it requires the use of oxygen. However, it provides more precise results during measuring.

Thee-point calibration is recommended for measuring hypoxic mixes, containing less than approximately 15 % oxygen. In this case, the third calibration gas should be a gas with zero oxygen content, i.e. pure helium or argon.

The values displayed on the device screen and the availability of advanced functions are limited. A significant extension of data visualization, control options, and the use of calculated values for gas preparation is achieved by connecting the analyzer to the Divesoft.App mobile application. Calibration can be performed either directly through the device menu or, after connecting to the analyzer, within the Divesoft.App environment. One-point and two-point calibration can be carried out directly on the device, while three-point calibration is available exclusively through the mobile application.

Enter the menu (long press) Scroll to Calibration with short presses and confirm (long press).

Short press to scroll through the options. Long press to select one of the options.

O2 Sensor – recommended to be performed regularly with a maximum interval of one day

He Sensor – the helium sensor does not need to be calibrated at all, or only in the case of an aberrant helium measurement. If you still decide to calibrate the helium sensor, then calibrate in air and without flow (disconnected tubing).

Return – takes you level back in the menu

Quit – return to the main screen

Oxygen sensor calibration
Short press to cycle through the options. Long press to select one of the options.

Air

calibrate with air
1. It is necessary to ensure that there is air on the sensor. If you have measured a gas other than air before calibration, you can speed up the venting of the measuring labyrinth by sucking the gas out of the measuring inlet port with your mouth.
2. Long press to select Air calibration 3. Short press to start calibration / Long press to cancel calibration 4. Wait for the values to stabilize (the countdown at the bottom of the screen) 5. Confirm the calibration with short press

Oxygen

calibrate with 100% oxygen.
1. It is necessary to ensure that 100% oxygen is present at the sensor. Use a gas source where you can be sure of the correct composition, quality and purity. For calibration, preferably connect one of the DIVESOFT flow limiters and connect the tubing to the ECHO inlet measuring port.
2. Long press to select Oxygen calibration
3. Short press to start calibration / Long press to cancel calibration
4. Wait for the values to stabilize (the countdown at the bottom of the screen)
5. Confirm the calibration with short press

Air+O2

two-point calibration with air and oxygen for more accurate calibration. Long press to select Air+O2

Step 1 – air
1. It is necessary to ensure that there is air on the sensor. If you have measured a gas other than air before calibration, you can speed up the venting of the measuring labyrinth by sucking the gas out of the measuring inlet port with your mouth.
2. Short press to start calibration / Long press to cancel calibration
3. Wait for the values to stabilize (the countdown at the bottom of the screen)
4. Short press to confirm the calibration step 1 and move to calibration step 2

Step 2 - oxygen
1. It is necessary to ensure that 100% oxygen is present at the sensor. Use a gas source where you can be sure of the correct composition, quality and purity. For calibration, preferably connect one of the DIVESOFT flow limiters and connect the tubing to the ECHO inlet measuring port.
2. Short press to start calibration / Long press to cancel calibration
3. Wait for the values to stabilize (the countdown at the bottom of the screen)
4. Confirm the calibration with short press

Correction of the oxygen content in the air

The oxygen content of the air is not constant, but varies with ambient conditions. The amount of oxygen is displaced by water vapour in the air. Therefore, the oxygen content decreases with increasing temperature and humidity. To accurately calibrate the oxygen sensor, use the correction tables below and set the correct value when calibrating to ambient air. Correction of the oxygen content in the air

06. Calibration Using the Mobile Application

Calibration Using the Mobile Application Calibration performed through the Divesoft.App is more user-friendly, clearer, and provides extended functionality compared to calibration performed directly on the device. In addition, the mobile application allows three-point calibration, which improves accuracy when analyzing hypoxic gas mixtures.
To use the mobile application, the app must be downloaded, installed, and paired with the ECHO analyzer (see chapter Connection to Mobile App). Multipoint calibration

Calibration Procedure
1. After pairing, open the Divesoft.App.
2. Enter the Analyzer section.
3. Press and hold the red “Calibrate” button.
4. Select one-point, two-point, or three-point calibration.
(An explanation of calibration types and their recommended use is provided in Chapter 05 – Calibration of the Oxygen Sensor.)
5. Connect the calibration gas and open the valve.
6. Wait until the sensor reading stabilizes.
7. Once the sensor is stable, confirm the calibration point in the application and connect the next calibration gas if required. Single point calibration

Multi-Point Calibration Notes
• When performing two-point or three-point calibration, calibration can begin with any calibration gas.
• The calibration points may be completed in any order, allowing flexibility based on gas availability.
• This approach is especially useful in field conditions or when working with hypoxic mixtures.

07. Ambient pressure

Analyzer is equipped with a barometric pressure sensor. Thanks to this device can be calibrated for the atmospheric conditions and altitude. The atmospheric pressure and altitude can be displayed in the menu ambient pressure. Altitude is calculated from the ambient pressure and, depending on atmospheric conditions may differ from reality.

08. Helium sensor calibration

The helium sensor used in the ECHO analyzer is factory calibrated during the manufacturing process. Thanks to the measurement technology employed, the sensor exhibits excellent long-term stability, and no user calibration is required during normal operation.
Because helium measurement does not rely on consumable or aging-sensitive components, the sensor output remains stable over time. As a result, routine or periodic calibration of the helium sensor is not necessary.
For this reason, helium sensor calibration is not available in the ECHO device menu, and no calibration option is provided for helium measurement.

09. Carbon monoxide sensor calibration

10. Measuring O2 and He concentration

The ECHO analyzer is designed for simple and reliable analysis of breathing gases used in diving. The ECHO analyzer allows users to monitor measured gas values directly on the ECHO device display or, when connected to a mobile device, on a smartphone or tablet using the Divesoft.App in Analyzer mode.

The analyzer is equipped with a built-in basic flow limiter, which can be placed directly against the cylinder valve. This solution is suitable for the analysis of air and nitrox mixtures.
For helium-containing mixtures (trimix or heliox), the use of an additional external flow limiter is recommended. A dedicated flow limiter (e.g. Flow Limiter Mk2) ensures accurate and stable gas sampling while minimizing unnecessary gas loss during the analysis process.

Analysis Steps
1. Ensure that the analyzer is powered on. Upon activation, the analyzer automatically switches to oxygen and helium measurement mode. No additional setup is required.
2. Place the built-in flow limiter against the cylinder valve. If an external flow limiter is used, connect the flow limiter to the cylinder valve and link it to the opening of the ECHO flow limiter using the supplied hose.
3. Slowly open the cylinder valve to allow gas to flow into the analyzer.
4. After approximately 5–10 seconds, the measured gas composition will be displayed on the ECHO analyzer screen. If the analyzer is connected to the mobile application, the measured values will also be displayed on the mobile device.
5. Wait until the displayed values stabilize before recording or confirming the measurement result. Stable readings are essential for accurate gas analysis.

11. CO detection

Carbon monoxide is a substance that is produced by imperfect combustion. It is therefore present around open fires or in the exhaust gases of combustion engines. Carbon monoxide has a direct effect on human health and is life-threatening in combination with high ambient pressure. The natural concentration of carbon monoxide in the air is around 0-10 ppm, in urban areas this can be as high as 200 ppm. The first signs of carbon monoxide poisoning at atmospheric pressure appear at a concentration of around 200 ppm, with life-threatening concentrations above 400 ppm.

In a hyperbaric environment the partial pressure of CO increases, therefore when using diving breathing gases the maximum permissible level of CO in the mixture is 5 ppm.

If the limit is exceeded, an alarm appears on the ECHO display.

In the app, you can click the Gas quality bar, which will show you the current CO concentration. In case of dangerous values, the bar will turn red and warn you of the dangerous value.

12. Maximum Operating Depth (MOD) Display

The calculation and display of Maximum Operating Depth (MOD) are available exclusively through the mobile application. When the analyzer is connected to the mobile device, MOD values are shown in the Divesoft.App in Analyzer mode. The application displays three separate MOD values, each corresponding to a different maximum allowable oxygen partial pressure (PO₂).

Default MOD Settings By default, the following PO₂ limits are used for MOD calculation:

• PO₂ = 1.2 bar
• PO₂ = 1.4 bar
• PO₂ = 1.6 bar

These values correspond to commonly accepted oxygen exposure limits in diving practice:

• PO₂ 1.4 bar – standard limit for recreational diving
• PO₂ 1.6 bar – typical limit for decompression gases
• PO₂ 1.2 bar – a conservative limit suitable for demanding conditions or increased safety margins

Customizing PO₂ Limits
If different PO₂ limits are required, the values can be adjusted directly in the mobile application. This may be useful, for example, when analyzing diluent gases, where a lower maximum PO₂ value (such as PO₂ = 1.0 bar) is preferred.

To change the PO₂ limits:
1. Open the Divesoft.App.
2. Switch to the Analyzer section using the bottom navigation bar.
3. Enter the Analyzer settings.
4. Adjust the PO₂ values as required.
The MOD values will be recalculated automatically based on the new settings.

13. Printing an Analyzed Gas Label

Printing a gas analysis label is available only through the Divesoft.App.

After completing the gas analysis and connecting the analyzer to the mobile application, proceed as follows:
1. In the Divesoft.App, press the Print button.
2. The application generates a PDF (.pdf) file, which is saved on the mobile device.
3. The PDF file can be shared using any compatible application on the smartphone or tablet.
4. The label can be sent to a label printer and printed for marking the cylinder with the analyzed gas information.

Label

This function allows clear and standardized labeling of breathing gas cylinders directly after analysis.

14. Setup menu

Enter the menu by press and hold the button.

The Setup menu provides access to device configuration and system settings. It contains the following items:
• Bluetooth
• Config.
• Screen
• Factory def.
• Return
• Quit
Selecting Return moves one level back in the menu structure. Selecting Quit exits the menu and returns the device to measurement mode.

Bluetooth
The Bluetooth menu contains options related to pairing the ECHO analyzer with a mobile device.
Available options:
• BLE pairing Initiates Bluetooth pairing with the mobile application.
• Erase pair. Deletes the current pairing with the mobile application and frees the analyzer for pairing with a new mobile device.

Config.
The Config. menu contains sensor-related configuration options.

Sensor
Select the currently used oxygen sensor type:
• R22 Standard galvanic oxygen sensor.
• DVO2 Solid-state oxygen sensor.

⚠️ Important: Only Dive O₂ solid-state oxygen sensors are supported. To connect a Dive O₂ sensor, a special interface cable is required and must be requested separately.
Dive O₂ sensor characteristics:
• Extremely long service life (more than 15 years)
• Reduced calibration requirements
• Must not be exposed to temperatures exceeding 60 °C

N₂ Src
Select the nitrogen reference source used for calculations:
• Atmospheric nitrogen with residual argon
• Pure nitrogen
This setting is intended primarily for laboratory measurements or specialized use. For standard diving gas analysis, the difference between these options is negligible. Units Setting measurement units between imperial and metric

Screen
The Screen menu allows customization of display appearance.
Available options:
• Orient. Sets the display orientation in 90° increments.
• Inverse Switches display rendering between:
o black text on a white background, and
o white text on a black background.
• Splash Configures the startup screen animation:
o Full – full startup animation
o Short – displays only hardware and software version information

Factory def.
Selecting Factory def. restores all device settings to their original factory defaults.

15. Measurement units

The ECHO analyzer supports both metric and imperial unit systems. The selected unit system affects the display of depth and pressure-related values where applicable.

Regardless of the selected unit system, the following measurement units are always used:
• Oxygen partial pressure (PO₂): displayed in bar
• Gas composition: displayed in percent (%)
• Carbon monoxide (CO): displayed in parts per million (ppm)

Carbon Monoxide Unit – ppm
ppm (parts per million) is a unit expressing the concentration of a gas as the number of parts of that gas per one million parts of the gas mixture.
In practical terms:
• 1 ppm means 1 part of CO per 1,000,000 parts of breathing gas
• ppm is a ratio, not an absolute pressure value

Relationship Between ppm and Pressure
Although ppm is a concentration ratio, it is directly related to pressure:
• The partial pressure of CO is proportional to its concentration (ppm) and the ambient pressure.
• As ambient pressure increases (for example with depth), the partial pressure of CO increases, even if the ppm value remains the same.
This means that:
• A gas mixture with a fixed CO concentration (e.g. 5 ppm) becomes more hazardous at greater depths, because the CO partial pressure rises with increasing pressure.

For this reason, CO limits are defined in ppm at surface pressure, and strict limits are applied to breathing gases intended for diving.

16. Gas calculations using a mobile app

By using the mobile application, the functionality of the ECHO analyzer is significantly extended. One of the key features is the ability to perform breathing gas calculations for dive planning and gas mixing calculations, including the generation of a final gas preparation recipe. All calculations are performed within the Divesoft.App after the analyzer is connected.

Blender

Ideal Gas Calculation
The application allows calculation of an ideal breathing gas for a specific dive depth based on user-defined parameters. The gas composition is calculated according to the parameters that are actively entered. If certain parameters are not specified, the application automatically prioritizes the remaining defined limits.

For example:
• If a maximum gas density is specified but END is not entered, the application calculates the gas based on the maximum allowed density and the configured maximum PO₂. The corresponding END is then calculated automatically.
• The same logic applies to other parameters such as PO₂ limits, END, or gas density.

Conversely, if a specific gas composition is entered, the application calculates the usable depth range and the gas properties at the selected depth.

Gas Mixing
To prepare a gas mixture, enter the existing gas in the cylinder at the bottom of the screen. The application then calculates a step-by-step filling procedure to achieve the desired final mixture.

An option “Heliair only” can be enabled to avoid the addition of pure oxygen during the mixing process.

Simulator
The Simulator tab allows calculation of the resulting gas mixture when combining gases with defined pressure and volume by gas transfer.

This includes:
• Mixing gases from multiple cylinders (multi-step gas transfer)
• Topping up a mixture with compressor air to a specified pressure
Additional cylinders can be added to simulate complex or multi-stage filling procedures.

Saving Gas Mixtures
Any calculated or simulated gas mixture can be saved in the My Cylinders section for later reference or reuse.

17. Charging and battery status

Charging the Battery
Charge the ECHO analyzer using its USB-C charging port and a standard USB power adapter with an output of 5 V and at least 0.5 A. Use a high-quality USB-C cable intended for charging electronic devices.
⚠️ Do not use fast-charging or high-voltage chargers. The analyzer is designed for standard USB power only.

Battery Status Indication
The current battery charge level is displayed on the right side of the ECHO display as a battery icon. This indicator provides a quick overview of the remaining battery capacity during operation.

Battery Charging Guidelines and Best Practices
The ECHO analyzer uses a rechargeable lithium-based battery. To maximize battery lifespan and maintain reliable performance, please observe the following recommendations:
• The battery performs best when kept between 20% and 80% charge during regular use.
• Frequent deep discharge to 0% should be avoided whenever possible.
• Continuous charging at 100% for extended periods may accelerate battery aging.

Recommended Charging Practice • Recharge the analyzer when the battery level drops to approximately 20–30%.
• Disconnect the charger once the battery is fully charged.
• Avoid leaving the device permanently connected to the charger.

When Not to Charge the Battery
• Do not charge the analyzer if it has been exposed to extreme temperatures.
• Avoid charging if the device is very hot or very cold; allow it to return to room temperature first.
• Do not charge the battery if the device or cable is visibly damaged.

Storage Recommendations
For long-term storage:
• Store the analyzer with the battery charged to approximately 40–60%.
• Recharge the battery periodically (every few months) to prevent deep discharge.
Following these guidelines helps reduce battery wear and ensures long service life of the internal accumulator.

18. Oxygen Sensor Replacement

Galvanic oxygen sensors have a limited service life because the sensing reaction gradually consumes the internal materials. Under normal operating conditions, the oxygen sensor typically requires replacement after 12–24 months, depending on usage, exposure, and environmental conditions.

Opened ECHO

Replacement Procedure
1. Ensure the analyzer is powered off and disconnected from any gas source.
2. Using a suitable tool, loosen and remove the five screws on the rear side of the analyzer.
3. Carefully open the rear cover of the analyzer.
4. Disconnect the oxygen sensor cable from the electronics.
5. Unscrew the oxygen sensor from the analyzer housing.
6. Disconnect the Molex connector from the sensor cable.
7. Connect the sensor cable to the new oxygen sensor using the Molex connector.
8. Screw the new oxygen sensor into the analyzer housing.
9. Reconnect the sensor cable to the electronics.
10. Close the rear cover and secure it with the five screws.

Sensor replacement

Important Note
⚠️ Do not screw the oxygen sensor into the analyzer with the cable attached.
Doing so may twist or damage the sensor cable.

19. CO Sensor Replacement

20. Battery replacement

The ECHO analyzer is powered by a rechargeable lithium battery. Over time and after many charge cycles, the battery capacity gradually decreases. When noticeably reduced operating time is observed, the battery should be replaced. Battery replacement

Replacement Procedure
1. Ensure the analyzer is powered off and disconnected from any power source.
2. Using a suitable tool, loosen and remove the five screws on the rear side of the analyzer.
3. Carefully open the rear cover of the analyzer.
4. Remove the battery from its holder by gently releasing it from the slot.
5. Disconnect the battery cable, which is permanently attached to the battery.
6. Insert the new battery into the designated holder.
7. Connect the battery cable to the electronics.
8. Close the rear cover and secure it with the five screws.

21. Storage when not in use for long periods

If the ECHO analyzer will not be used for an extended period of time, proper storage helps maintain device performance and prolong the service life of internal components.

General Storage Conditions
• Store the analyzer in a clean, dry environment.
• Avoid exposure to direct sunlight, moisture, and dust.
• Recommended storage temperature is 10 °C to 30 °C.

Battery
• Store the analyzer with the battery charged to approximately 40–60%.
• Avoid storing the device with a fully discharged or fully charged battery.
• Recharge the battery periodically during long-term storage to prevent deep discharge.

Oxygen and CO Sensors
• Store the analyzer in clean air, free of solvent vapors, exhaust gases, or other contaminants.
• Avoid exposure to high concentrations of oxygen, carbon monoxide, or other reactive gases.
• Do not store the device in sealed containers with chemicals or fuels.

Additional Notes
• Avoid mechanical stress or pressure on the device during storage.
• Allow the analyzer to reach room temperature before use after long-term storage.

22. Error and Warning Messages

The ECHO analyzer continuously monitors the status of its internal components and sensors. If a fault or abnormal condition is detected, an error or warning message is displayed on the screen. This chapter explains the meaning of these messages and provides basic guidance on how to proceed.

Messages Displayed During Power-On

ERROR: O₂ sensor missing, damaged or misconfigured
No functional oxygen sensor was detected.
This error may occur if:
• A solid-state oxygen sensor is connected but does not communicate with the device.
• An electrochemical oxygen sensor is connected, but its output voltage is below 0.5 mV.
Action:
Check that a compatible oxygen sensor is correctly connected and configured. Replace the sensor if necessary.

WARNING: O₂ sensor too weak – Replace sensor The electrochemical oxygen sensor output is low (sensor voltage < 5 mV).
This warning may also appear temporarily if the analyzer was previously exposed to a hypoxic gas mixture.
Action:
If the warning persists, replace the oxygen sensor.

ERROR: xxx doesn’t work correctly
A malfunction was detected in one of the internal components.
The placeholder xxx may refer to one of the following:
• He sensor
• Bluetooth adapter
• Barometer
• Humidity sensor
• CO sensor

For the CO sensor, this error may indicate that:
• The CO sensor is not installed,
• The sensor does not communicate correctly, or
• A different type of sensor is installed instead of a CO sensor (a CO sensor is mandatory).
Action:
Except for sensor replacement or correction of an incorrect sensor type, these errors require service inspection.

WARNING: Low / High temperature – may work incorrectly
The internal temperature of the analyzer is outside the specified operating range of 5 °C to 40 °C.
Action:
Allow the device to acclimate until it reaches the normal operating temperature range.

Messages Displayed During Operation

HAL ERROR: file fff, line X An internal system error has occurred.
Action:
This is a critical internal fault. The device must be sent to authorized service.

Troubleshooting Summary
• O₂ sensor errors can usually be resolved by checking, replacing, or correctly configuring the oxygen sensor.
• CO sensor errors may be resolved if an incorrect sensor is installed; otherwise, service is required.
• Temperature warnings are resolved by returning the device to the specified operating temperature range.
• All other hardware or system errors require professional service intervention.

23. Technical data

The ECHO analyzer is a compact, portable breathing gas analyzer designed for reliable analysis of oxygen, helium, and carbon monoxide in diving gases. The device combines long battery life, advanced sensor technology, and wireless connectivity with a mobile application. Dimensions

Display
• Type: HR-TFT (High Reflective TFT)
• Description:
High-contrast display with excellent readability, including outdoor and bright-light conditions (HR-TFT = High Reflective Thin-Film Transistor display)

Power Supply
• Battery type: Rechargeable lithiu m battery
• Battery capacity: 3.7 Wh • Operating time:
o up to 100 hours with R22S galvanic O₂ sensor
o up to 50 hours with DVO₂ solid-state O₂ sensor
• Charging interface: USB-C
• Charging parameters: 5 V / ≥ 0.5 A
• Typical charging time: approx. 2.5 hours

Sensors
Oxygen (O₂)
• R22S galvanic oxygen sensor (standard)
• DVO₂ solid-state oxygen sensor (optional)
o Solid-state measurement technology
o Extremely long service life
o Under normal use, expected to last for the entire lifetime of the analyzer
o For dive centers and filling stations, expected service life 15+ years

Helium (He)
• Solid-state helium sensor
• Service life: unlimited
• Factory calibrated
• No user calibration required

Carbon Monoxide (CO)
• Electrochemical CO sensor
• Manufacturer-guaranteed lifetime: 2 years from unpacking
• Recommended zero calibration: every 2–6 months in clean air
• CO warning threshold: 5 ppm

Connectivity and Features
• Bluetooth Low Energy (BLE)
• Connection to Divesoft.App
o Large and clear display of measured values
o Extended data visualization
o Calibration of sensors
o Firmware updates
o Label printing via the mobile application

Mechanical Design
• Compact handheld housing
• Integrated wrist strap

Dimensions
• Main body diameter: approx. 127 mm
• Body thickness: approx. 37.5 mm
• Body width: approx. 110 mm
• Overall length (including strap): approx. 410 mm

ECHO ANALYZER - USER MANUAL

Date of issue: 02 February 2026
HW 1.0, FW 1.6.3
Author: Jakub Šimánek
Published by Divesoft s.r.o.