Comparison CTW 8807W vs JJRC H31

The type of camera installation that the quadcopter is equipped with.

- Built-in. A camera that is permanently installed on the vehicle and cannot be removed without disassembling the fuselage. This is the simplest option for tech who want to use a quadcopter for photo and video shooting or for flying with a first-person view (see “Real-time broadcast”); In addition, this camera design is considered more durable and reliable than a removable one. On the other hand, it does not make it possible to remove the camera to make the car lighter or replace it with another one that is more suitable in terms of characteristics.

- Removable. As the name suggests, such cameras are installed on detachable mounts. Thanks to this, the customer can remove or install the camera, depending on what is more important to him at the moment - the light weight of the car or the presence of an electronic “eye” on board. Note that in some models you can install not only a standard device, but also a third-party device.

- Absent. Drones that are not equipped with cameras at all fall into two main categories. The first does not involve the use of any cameras at all; As a rule, it includes inexpensive devices primarily for entertainment purposes, for which the “peephole” is just an expensive and unnecessary excess, which also increases the weight of the entire structure. The second type is models with...the ability to install a camera. It includes quite advanced copters - up to powerful professional machines capable of carrying a digital SLR. This option will be useful for tech who would like to independently select a camera to suit their needs. However, we note that the second type may have an auxiliary “eye” for live FPV broadcasts (see below); however, if such a “peephole” does not allow for taking photos/videos, it is not considered a full-fledged camera, and its presence is indicated only in additional notes. — Thermal imaging. A camera operating on the principle of a thermal imager - it detects infrared radiation from heated objects and forms a characteristic thermal image visible to the drone operator. Each color in this image corresponds to a specific temperature. A thermal imager equipped in a drone opens up possibilities not available to traditional optical cameras. Thus, it can be used to distinguish a person or animal against a camouflage background or in dense vegetation in an area. Thermal imaging cameras also “see” perfectly in complete darkness.

Quadcopters with a thermal imaging camera are by no means a cheap pleasure. They are used by rescuers, military, law enforcement, repairmen, hunters and fishermen. In particular, drones with a thermal imaging camera help find living people when clearing rubble, and are widely used to search for possible fires, gas leaks from pipelines, etc. In some situations, the performance of a thermal imager may be low - for example, it is not able to clearly identify an object if its temperature coincides with the background temperature (which makes it difficult to use in hot weather). In addition, the resolution and detail of the picture, even in advanced models, is quite modest. Thermal cameras in drones can be built-in or detachable.

Resolution of the matrix in the standard camera of the quadrocopter.

Theoretically, the higher the resolution, the sharper, more detailed image the camera can produce. However, in practice, the quality of the "picture" is highly dependent on a number of other technical features - the size of the matrix, image processing algorithms, optical properties, etc. Moreover, when increasing the resolution without increasing the size of the matrix, the image quality may drop, because. significantly increases the likelihood of noise and extraneous artifacts. And for shooting video, a large number of megapixels is not required at all: for example, to shoot Full HD (1920x1080) video, which is considered a very solid format for quadrocopters, a sensor of only 2.07 megapixels is enough.

Note that high resolution is often a sign of an advanced camera with high image quality. However, this quality is not determined by the number of megapixels, but by the characteristics of the camera and the special technologies used in it. Therefore, when choosing a quadcopter with a camera, you should look not so much at the resolution as at the class and price category of the model as a whole.

The maximum resolution and frame rate supported by the aircraft camera when shooting in HD (720p).

HD 720p is the first high-definition video standard. Notably inferior to Full HD and 4K formats in terms of performance, it nevertheless provides pretty good detail without significant demands on the camera and processing power. Therefore, HD support is found even in relatively inexpensive copters. And in high-end models, it can be provided as an addition to more advanced standards.

In drones, HD cameras typically use the classic 1280x720 resolution; other, more specific options are practically non-existent. As for the frame rate, the higher it is, the smoother the video turns out, the less movement is blurred in the frame. In general, values up to 24 fps can be called minimal, from 24 to 30 fps — medium, from 30 to 60 fps — high, and speeds over 60 fps are used mainly for slow motion HD.

Possibility of online video broadcasting from the quadcopter to an external device — smartphone, laptop, control panel with display, virtual reality glasses, etc.

This feature provides several benefits at once. Firstly, it greatly simplifies the control of the device, even if it is within sight; and if the copter is not visible from the ground (which happens often, especially when using heavy professional equipment), then it is very difficult to do without "eyes on board". Secondly, live broadcasting makes it possible to use a drone for real-time observations, as well as full-fledged aerial photo and video shooting; recording of footage can be carried out both on an external device that receives the broadcast, and on the aircraft’s own carrier (usually a memory card — see below).

The specific features of the live broadcast for each model should be clarified separately; however, nowadays, thanks to the development of technology, such an opportunity is available even in low-cost devices.

Additional sensors provided in the design of the quadcopter.

— Heights. A sensor that determines the flight altitude of the machine. Such sensors can use the barometric or ultrasonic principle of operation. In the first case, the height is measured by the difference in atmospheric pressure between the current point and the starting point (that is, the sensor determines the height relative to the initial level); in the second, the sensor acts similarly to sonar, sending a signal to the ground and measuring the time it takes to return. Barometric sensors are not very accurate, but they work well at high altitudes — tens and hundreds of metres; ultrasonic — on the contrary, they allow you to accurately manoeuvre at low level flight, but lose effectiveness as you climb. However, in some advanced models, both options may be provided at once. Data from the height sensor can either be used by the quadcopter “independently” (for example, when hovering or automatically returning), or transmitted to the operator to the remote control or smartphone.

— Optical. A sensor that allows the quadcopter to "see" the environment in certain directions. One of the simplest variants of such a sensor is a downward-facing camera that allows the device to “copy” the surface under which it flies. Due to this, the machine, for example, can navigate indoors, where the signal from GPS satellites does not reach. In...addition to such a chamber, "eyes" can also be provided from different sides of the machine. Note that optical sensors have certain limitations in their use — for example, they lose their effectiveness on dark, shiny or uniform (without noticeable details) surfaces, as well as at high speeds.

— GPS module. A sensor that receives signals from navigation satellites (GPS, in some models also GLONASS) and determines the current geographical coordinates of the machine. Specific ways of using position data can be different: returning home, flying by waypoints (see below), recording a flight route, etc.

— Gyroscope. A sensor that determines the direction, angle and speed of the machine's rotation along a specific axis. Modern technologies make it possible to create full-fledged three-axis gyroscopes of very compact dimensions, and it is with such modules that quadcopters are usually equipped. On the basis of gyroscopes, automatic stabilization systems usually work, returning the car to a horizontal position after a gust of wind, collision with an obstacle, etc. At the same time, such equipment affects the cost of the device, and in some cases (for example, during piloting), automatic stabilization is more of a hindrance than a useful feature. Therefore, some low-cost, as well as advanced aerobatic quadcopters, are not equipped with gyroscopes.

The control method provided in the copter.

Modern drones are usually controlled by a remote control, a smartphone, or both. Here is a detailed description of each of these options:

— Remote control only. Management carried out exclusively from the complete remote control. The most common option, found in all varieties of drones — from the simplest entertainment models to high-end professional devices; and heavy commercial / industrial models (see "Type") are completely controlled exclusively in this way. Such popularity is explained by two points. Firstly, the functionality of the remote control can be almost anything — from a small device with a couple of levers and buttons to a multifunctional control unit with a screen for live broadcasts and displaying various specialized information. Thus, the equipment of the remote control can be optimally matched to the features of a particular copter. Secondly, you can install a powerful transmitter with a large range in the remote control (whereas the range of smartphones is very limited, and it also depends on the specific gadget model). Well, besides, the control panel is initially supplied with the drone (except that the batteries in some models need to be purchased separately).

— Smartphone only. Management carried out exclusively from a smartphone (or other similar gadget — for example, a tab...let) through a special application; communication is usually carried out via Wi-Fi. This option is good because almost any functionality can be provided in the control application; and the copter itself turns out to be convenient in transportation — in the sense that you do not need to carry a separate remote control with it. However, the range in such a control is very small — even under perfect conditions, it usually does not exceed 100 m, and in some models it does not even reach 50 m; and the actual communication range also strongly depends on the characteristics of the control gadget. In addition, the controls on the touch screen are not tactile, making blind control almost impossible. As a result, this option is very rare — in certain models of mini-drones and selfie-drones (see "In the direction"), for which the absence of a remote control and ease of carrying are important, and the described disadvantages are not critical.

— Remote control and smartphone. The ability to control the drone both from the remote control and from a smartphone. The features of both options are described in detail above; and their combination is found mainly in relatively simple devices, for which the shortcomings of control via a smartphone are not critical (although there are exceptions). At the same time, the main option for such copters is often control from an external gadget, and the remote control may not be included at all; This point does not hurt to clarify before buying. However, anyway, this control format gives the user the opportunity to choose the best option for a specific situation. For example, for recreational flights during a "sally" in nature, you can get by with a smartphone, and for aerobatic training, a remote control is better. So most modern quadcopters that can be controlled from a smartphone / tablet fall into this category.

The range of the drone is the maximum distance from the control device at which a stable connection is maintained and the device remains controlled. For models that allow operation both from the remote control and from a smartphone (see "Control"), this item indicates the maximum value — usually achieved when using the remote control.

When choosing according to this indicator, note that the range is indicated for perfect conditions — within line of sight, without obstacles in the signal path and interference on the air. In reality, the control range may be somewhat lower; and when using a smartphone, it will also depend on the characteristics of a particular gadget. As for specific figures, they can vary from several tens of metres in low-cost models to 5 km or more in high-end equipment. At the same time, it should be said that the greater the range of communication, the higher its reliability in general, the better the control works with an abundance of interference and obstacles. Therefore, a powerful transmitter can be useful not only for long distances, but also for difficult conditions.

The presence of a mount for a smartphone or tablet on the quadcopter control panel.

This feature allows you to fix the electronic gadget in such a way that in the process of controlling the machine, its screen is constantly in front of the operator's eyes. This function is relevant primarily for live broadcasts from the device (see "Live broadcast (FPV)"). At the same time, the mount for the gadget can be found both in quadrocopters that initially have FPV mode, and in models that are not equipped with cameras (in which the possibility of live broadcasting depends on the characteristics of the installed camera). However, note that the size of the mount and its compatibility with various electronic devices may be different, so before buying it's ok to clarify what exactly can be installed on the remote control.

The presence of an information display on the quadcopter control panel.

Note that this feature should not be confused with the FPV broadcast screen (see below). The information display is usually a simple segment display capable of displaying numbers, individual letters, and, on some models, a limited set of special icons. However, even such equipment significantly expands the capabilities of the remote control and allows the operator to receive a lot of additional information: battery charge, signal level, range, flight altitude, etc. At the same time, the auxiliary screen is inexpensive and can be used even in low-cost models. And in advanced drones, it may well complement the broadcast display: separating data into different screens contributes to ease of control.