Comparison TFA Hitrax Step 3D vs Beurer PM 18

— Pedometer. This category comprises devices primarily designed to count the number of steps taken by the user. Additional measurements in the design are directly related to step counting and may include movement speed, distance traveled, energy consumption, etc. Steps are typically counted based on accelerometer data, responding to the characteristic shaking during walking. Some pedometers use GPS modules instead of accelerometers, measuring distance traveled rather than individual steps. Another specific variety is designed for swimmers, measuring strokes instead of steps. Despite this difference, they share key features with traditional pedometers and are included in the same category.

— Heart rate monitor. Devices designed to track the user's heart rate and the corresponding calculations based on this data. They are not able to work with step counting — unlike pedometers and combination metres, see below. There are both devices with a built-in sensor, and with a remote one.

— Heart rate monitor/pedometer. Combined models integrate the functionalities of both heart rate monitors and pedometers, measuring both the number of steps and heart rate, along with related parameters. These devices offer versatility, but their development involves technical challenges that can impact measurement quality and overall cost. As a result, there are relatively few...models of this type available on the market.

— Pulse oximeter. These devices can measure both heart rate and blood oxygen saturation and typically resemble a characteristic "clothespin" attached to the finger. Using non-invasive methods, they determine blood oxygen levels without causing skin damage. While suitable for sports applications, they also find use in medical settings, serving as a means to monitor a patient's condition in the absence of more advanced medical equipment. However, due to the inconvenience of the finger "clothespin" during vigorous activity, these devices are more aligned with medical instruments in their intended use.

— Heart rate sensor. These models are external heart rate sensors meant for connection to other devices such as heart rate monitors, exercise equipment, or smartphones. They are not designed for stand-alone use. While these cardiac sensors have limited capabilities, this is not a drawback but a specific feature inherent in their application format. The expectation is that additional measurements will be conducted by an external device, and the sensor's role is to provide the necessary data for this purpose.

— Wrist. Worn on the wrist like a traditional watch, many models of these devices closely resemble electronic watches. This method of attachment is highly convenient, especially for heart rate monitors, as the device sits directly on the skin, allowing for easy integration of pulse sensors. However, for pedometers, wrist mounting has drawbacks due to various vibrations affecting accuracy. To compensate, devices require intricate accelerometer calibration or the use of a GPS module, both influencing the device's cost.

— Forearm. Placing the sensor on the forearm (parts of the arm from the elbow and above) is both easier and less inconvenient. However, the distance of the sensor from the heart can affect the accuracy of the measurement. Therefore, most of the cardio sensors are made exactly on the chest (see paragraph above).

— Chest. Secured on the chest with a specialized belt, this method positions the device close to the heart, ensuring highly accurate heart rate tracking. However, devices with this setup typically lack displays as checking them would be inconvenient. This configuration is exclusively employed in cardiac sensors (see "Type").

— Neck. Traditionally, these devices are attached to a cord or ribbon for wearing around the neck. While this is the standard method, many models offer versatility,...allowing them to be placed in a pocket. Some devices in this category are not designed for cord attachment at all and are somewhat loosely classified. Pedometers are commonly found in the "neck" device category.

— Shoes. Positioned on the upper part of shoes, typically where lacing is found in classic sneakers, this method is convenient for pedometers, ensuring accurate step tracking. However, it may not be compatible with all shoes, and using certain functions can be challenging, requiring bending over or removing the device to interact with the display. As a result, this option hasn't gained widespread popularity.

— Fastening with a clip. Featuring a universal clip or "clothespin" in its design, this allows the device to be easily attached to the edge of clothing, such as a belt, collar, or pocket. Common in classic pedometers (see "Type"), these devices don't require direct contact with the skin during operation. The clip attachment method is more versatile than mounting on shoes and, for some users, is even more convenient than wearing the device around the neck or on the wrist/shoulder.

There are models that have several purposes — usually, these are devices on wrist, supplemented with alternative options (for example, a clip).

— External. An external chest sensor is directly attached to the chest using a special belt, typically communicating wirelessly with the main unit. This communication can be through a universal interface like Wi-Fi or Bluetooth, a specialized one such as ANT +, or even a distinct natural frequency. This design ensures accurate measurements, allows flexibility in fastening the main unit of the heart rate monitor, and minimizes inconvenience. The sensors don't restrict movements much and have lenient requirements for dimensions and weight, contributing to cost-effectiveness. As a result, chest sensors are widely popular.

— Built-in. Built-in sensors refer to sensors installed directly in the main unit of the heart rate monitor, consistently in contact with the skin. This design is convenient as everything needed is housed in a single unit, reducing the risk of losing the sensor. They offer continuous heart rate monitoring, but the options for fastening are limited (see "Purpose"), typically restricted to the wrist due to the need for constant skin contact. Strict requirements for dimensions, weight, and the design's complexity impact the cost, and measurement accuracy is generally lower. Due to these factors, built-in sensors are not widely adopted.

— Finger sensor. A finger sensor reads heart rate data from the fingertip, typically the index finger. In...some wrist-mounted models, these sensors are integrated into the case, requiring touch for pulse measurement. Unlike built-in sensors, finger sensors don't provide continuous monitoring but offer higher accuracy. Another option is a clip-like "clothespin" attached to the fingertip, akin to sensors in medical equipment. While these allow constant pulse monitoring, they are less convenient for vigorous activity and are uncommon.

— Ear clip. Another type of "clothespin," in this case designed for attachment to the earlobe. These clips are smaller and less restrictive than finger clips, making them more suitable for active activities. However, achieving light and compact sensors with wireless connections is challenging, and additional wires can make the structure unwieldy. As a result, ear clips are uncommon, primarily found in neck-mounted models (see "Purpose").

The presence of backlight in the design of the display, which is equipped with the device.

Its own backlight allows you to see the image on the screen regardless of the ambient light — in other words, such a screen can be used even in complete darkness. Most often, it turns on for a short time, by pressing a special button — this allows you to minimize additional battery consumption. The exception is displays built on the basis of OLED matrices — in them each pixel is a separate luminous element, the image glows constantly, and energy savings are ensured by high efficiency and some design and software tricks.

Measurements and calculations that can be carried out with the device.

— Heart rate. Heart rate measurement in real-time is a crucial feature for devices with a heart rate monitor function and is primarily the main function for heart sensors and pulse oximeters. In fitness, heart rate is a key parameter, aligning with various training goals such as fat burning, maintaining shape, or cardiovascular strengthening. Many models can also detect critical situations like heart rhythm disturbances or excessive heart rate, providing user warnings. However, it's important to note that not all heart rate monitors or combined devices offer continuous monitoring; some models require touching the sensor for measurements. Therefore, for constant pulse data, ensure the selected device supports continuous monitoring.

— The level of oxygen in the blood. The pulse oximeter function measures blood oxygen saturation levels using a specialized sensor in a non-invasive manner, without puncturing or damaging the skin. It's important to acknowledge that the oxygen level sensor is not a certified medical device. However, it effectively responds to critical decreases in saturation, such as those experienced by climbers at high altitudes or individuals with specific respiratory conditions.

— Perfusion Index (PI). A parameter found exclusi...vely in pulse oximeters (see “Type”). Perfusion Index (PI) is a measure of blood flow in the finger being measured. The PI indicator is measured as a percentage and can vary from 0.3 to 20%. A value in the range of 4 – 7% is considered normal. If you deviate from this range, the saturation measurement results may be distorted.

— Number of steps. Step count measures the number of individual steps taken by the user, aiding in achieving recommended activity levels for a healthy lifestyle, fitness, or physical therapy. The function calculates steps taken in various ways, such as recording results for multiple sessions or days, displaying total and average numbers, remembering target values, and signaling their achievement. It's important to note that not all devices with a pedometer function (refer to "Type") support step count measurements. Some devices, designed for professional sports where movement speed is crucial, may prioritize other metrics over step count.

— Distance travelled. The function measures the total distance covered by the user. Basic models calculate distance in real-time, while more advanced ones can summarize results and work with target values. There are two main measurement methods: classic pedometers determine distance by multiplying the number of steps by the set step length (refer to "Individual settings"), while models with GPS use satellite navigation data (see "Features"). The first method has a larger error, but it's often not critical. The second method is more accurate but is costlier and may not work well in areas with weak satellite signals, such as dense urban areas or indoors.

— Movement speed. Measurement of the current movement speed. Like the distance traveled, this indicator can be calculated in two ways — by the number of steps or by data from the GPS module; see above for details on both methods. The simplest measurement option provides measuring the speed only at the current time, however, additional features may be provided — for example, building a schedule for a workout.

— Energy expenditure (calories). The function measures the amount of energy expended during a workout, commonly referred to as "burned calories". Monitoring energy consumption is crucial in weight management training programs as it helps track metabolism. However, it's essential to note that modern heart rate monitors and pedometers do not directly determine actual energy consumption. Instead, they estimate the number of calories based on factors such as heart rate, movement speed, number of steps, user's personal characteristics (refer to "Individual settings"), and other indirect parameters. Despite being approximate, these calculations are generally accurate enough for practical application.

— The amount of burning fat. The function calculates the amount of burned fat during a workout, typically measured in weight units such as grams. Similar to energy consumption, the device doesn't directly measure the actual fat burned but estimates it from various auxiliary data. The accuracy of these measurements is relatively low, and this parameter is not a primary focus in fitness. However, tracking the amount of fat eliminated can serve as additional motivation for users.

— Average/maximum heart rate. Calculation of the average and maximum value of the heart rate for a certain period of time (usually for one training session). These calculations are based on general information about the heart rate; about its meaning, see above.

— Activity time. The function measures the total duration of the user's physical activity, specifically recording only the time during which the device sensors detect the activity. Breaks in sessions are excluded from the recorded time. For instance, if you walked 1000 steps in 20 minutes with a 3-minute break, the recorded activity time would be 17 minutes. This feature distinguishes it from a regular stopwatch (refer to "Features") and enables accurate tracking of the duration and intensity of training loads.

Sensors and measurement modules provided in the design of the gadget.

— GPS module. A GPS receiver helps pinpoint a device's current coordinates. Its applications range from calculating distances in sports gadgets to more advanced functions such as full-fledged navigation with optimal route determination, depending on the device's features.

— Altimeter. The altimeter, detecting device height, operates through various principles. In GPS-equipped models, it uses a geographic database to determine height based on coordinates. Those with a barometer calculate altitude from pressure differences, often referencing a starting point or a hypothetical sea level. While the GPS method is more precise in measuring ground surface height, it overlooks objects like stairs or towers. Barometer-based measurement is affected by weather changes but provides the actual height of the device.

— Thermometer. A sensor that detects the ambient temperature. This data can be useful both for assessing general comfort levels (personal impressions can be deceiving, especially if you will be outside for a long time), and for specific tasks — for example, improvised weather forecasts (in combination with barometer data and other observations).

— Barometer. A s...ensor measures atmospheric pressure, commonly used to forecast weather changes. Its applications extend beyond this, including the ability to gauge height differences even when a dedicated altimeter is not present. It's worth noting that this function is applicable only to gadgets capable of displaying atmospheric pressure data on the screen; altimeters with barometric sensors lacking this feature are not included in this category.

— Compass. A traditional compass is a device for determining the cardinal directions, one of the basic instruments for any navigation. In modern heart rate monitors and other sports gadgets, usually, a digital compass is used, which displays data directly on the display.

— Clock. Classic clock — a function of displaying the current time. The clock provides not only time tracking, but also some other features — for example, they are mandatory for devices with an alarm clock (see below).

— Alarm clock. The presence in the device of the alarm clock function — the sound signal at a specified time. In the simplest models, this signal can only be programmed for one specific time, more advanced devices allow you to remember several alarms, and if you have a calendar (see below), you can also set them on certain days (for example, only on weekdays or even on specific dates) .

— Calendar. The device includes a calendar function, displaying at least the current date, and some models may offer advanced features like viewing monthly dates in table form. Calendar data is often used by other functions, ranging from the built-in training diary to the alarm clock.

— Stopwatch. The device can function as a stopwatch, measuring time intervals with high accuracy, down to tenths or even hundredths of a second. The stopwatch starts and stops at the user's command, and many models offer special measurement modes, including recording intermediate results or the time of each individual lap. This makes stopwatches significantly mor...e convenient for measuring time intervals than regular watches.

— Timer. The ability to operate the device as a timer — that is, in the countdown mode, with a signal at the end of the specified segment. This feature will be useful when performing exercises that are clearly limited in time: setting a timer and waiting for a signal is more convenient than constantly looking at the clock.

— Lap counter. The device has the capability to record data (time, speed, calories burned, average heart rate, etc.) for each individual lap, such as during running. Typically, this is achieved with a designated "Lap" button that, when pressed, captures data for that lap and initiates a new countdown. This function enables monitoring of training dynamics, identifying the most effective laps, while simultaneously recording overall training data. Some devices also offer a lap countdown feature, where the user sets a specific number of laps, and the device signals the end of the workout after that set number is completed. This simplifies the process of tallying the total number of laps.

— Multisport. The device includes a "multisport" function designed to enhance usability during multisport activities — training or competitions involving various sports stages. While non-specialized devices can be used for such activities, those with the dedicated "multisport" feature offer greater convenience. Optimized for this mode of use, they feature built-in software modes like "Running" or "Rowing" that can be easily switched between. These devices save complex data in a format conducive to further processing and analysis.

Personalized settings enable users to tailor the device to their individual characteristics. Modern fitness devices often incorporate the following customization options:

— Gender. Ability to set the gender of the user. With the same age, height and weight, the male and female bodies still differ in metabolic characteristics, optimal heart rate values and some other significant parameters.

— Age. Ability to set the user's age. This indicator primarily affects the general condition of the body and its ability to endure high loads (although these points also depend on other factors, ranging from physique to physical fitness, previous diseases, etc.).

— Weight. The option to input user weight is used in calculating optimal heart rate, energy expenditure, and fat burned (refer to "Possible measurements"). When combined with height, it provides insights into physique specifics and the need for weight management.

— Height. Ability to set the user's height. This indicator is practically not used on its own — it is usually used in combination with weight (see above) when determining physique. In addition, some pedometers (see “Type”) can calculate stride length from height data (although this setting is more common, see below).

— Step length. Ability to manually set the user's average step length. The main scope of this data is the calculation of the distance traveled in pedometers (see "Possible measurements")....

— Individual training area. Users can manually define an individual training zone, specifying the desirable heart rate range during exercise, with a warning signal for exceeding it. While many fitness gadgets can automatically calculate an optimal range based on workout goals and individual settings, certain situations, such as recovery after illness or exceptional physical fitness, may require specific considerations. Some devices with a heart rate monitor function enable users to manually set a personalized training zone, factoring in all relevant parameters.

The degree of water protection provided for in the design of the device.

The specified underwater depth for device functionality is often given, but it's important to note that these values are somewhat arbitrary and don't accurately reflect real-world water resistance. The assessments only consider static pressure, neglecting dynamic pressure created by movement, including immersion.

Effectively, genuine water resistance can only be claimed at a minimum of 30m. Even then, such capabilities only withstand minor exposure like rain. Brief water exposure, like swimming, might be permitted at 50m (not universally). For depths of 2 — 3m, 100m is necessary, and serious diving requires a minimum of 200m (or 300m for depths exceeding 20m).