Ajax radio protocols
This page explains factors that affect the quality of radio communication and technologies that enable Ajax devices to consistently transmit events and alarms with photo verification over long distances.
Using polling, Jeweller displays the real-time device status and transmits alarms, events, and all measured readings to the Ajax apps. It features encryption and authentication to prevent spoofing.
Serving as a backup communication channel, Wings is designed to transfer large data packets, primarily for individual settings such as interface languages and firmware updates.
Radio communication transmits data via radio waves. Under ideal conditions, there are no obstacles or interference in the path of the waves, and they move from the transmitter to the receiver using the shortest path. Open space conditions provide the maximum communication range. This range serves as a generally accepted benchmark for comparing the capabilities of radio technologies and equipment using radio communications.
Jeweller and Wings radio protocols have maximum communication ranges of 2,000 and 1,700 meters, respectively.
Factors affecting the radio communication range
In real-life conditions, radio waves encounter obstacles. While waves pass through certain obstacles without loss and reflect from others, some obstacles absorb radio waves. The effects of obstacles depend on the material, shape, and thickness. Rain, snow, dust, even very humid air, while often be insignificant, still act as obstacles, as do people. Generally, when radio signals encounter obstacles, they attenuate, losing some of their power.
The more obstacles a signal encounters, the shorter the data transmission range becomes. A additionally, reflected, radio waves change direction.
Other waves of the same frequency, as well as radio waves from the same transmitter reflected from obstacles, can create interference in the path of radio waves. Their mutual influence, known as interference, does not always lead to signal attenuation, but it usually has a negative effect.
In-phase signals are amplified
Anti-phase signals are attenuated
Jeweller and Wings radio protocols operate at 868 or 915 MHz, depending on the region of sale. These bands are much less noisy compared to Wi-Fi frequencies — 2.4 GHz and 5 GHz — as well as 433 MHz, which are used by IoT electronics, remote control units, and outdated security alarm systems.
Radio waves can pass through small holes without significant attenuation, a property known as diffraction.
The presence of a ventilation duct in a non-radiotransparent wall, under certain conditions, ensures stable radio communication in the adjacent room.
Effect of obstacle material on a radio signal
Depending on the material, obstacles can reflect radio waves, absorb them, thereby depriving them of some of the power, or have no effect on the radio signal. Materials that do not affect radio signals are called radiotransparent. The higher the signal absorption coefficient and the thicker the obstacle, the greater the impact on radio transmission.
Low signal absorption coefficient — up to 3 dB
50% power loss; transmission range 30% shorter
Dry red brick 90 mm thick
Gypsum board 100 mm thick
Dry wood 80 mm thick
Glass 15 mm thick
Average signal absorption coefficient — 5–20 dB
Power reduces 10 times; transmission range reduces by 60%
Brick 250 mm thick
Breeze block 200 mm thick
Concrete 100 mm thick
Masonry 200 mm thick
Signal absorption coefficient — more than 20 dB
Power reduces more than 100 times; transmission range reduces by 70%
Concrete 300 mm thick
Reinforced concrete 200 mm thick
Aluminum and steel beams
Large aquarium filled with water
Signal strength reduction to 10%
Obstacles reflecting signals
At our frequencies, an object with a straight surface and a size of at least 30 × 30 cm will reflect the signal.
All surfaces reflect radio signals to some extent. However, metals and mirrors do so to a greater extent.
Calculating the radio communication range of Ajax devices
No theory — just practical trials with devices from retail distribution. The trials are conducted at a test site with minimal radio noise and favorable weather conditions. A constant exchange of data between the hub and the device is maintained, with the distance between them gradually increasing. As soon as the hub ceases to acknowledge the reception of events, the communication range is recorded. After confirming the value with multiple tests, the device is assigned the "communication range" characteristic.
This approach is the industry standard for determining communication range and is required to compare devices within the same manufacturer's product line as well as competing solutions from different manufacturers.
Why Ajax devices have different radio communication ranges
On the device side, the data transmission range depends on the transmitter’s signal strength, antenna parameters, and receiver sensitivity. Jeweller and Wings radio protocols ensure two-way communication between devices. Therefore, each device both transmits and receives signals.
Detectors, relays, and other Ajax devices have different hardware components and antennas, different enclosure materials, and different power consumption — each factor affects the maximum range of data transmission and reception.
When assessing the communication range between two devices, one should focus on the device with the smaller maximum communication range. For example, if Hub has a range of 2,000 meters, and MotionProtect has a range of 1,700 meters, these devices will be able to exchange data at a distance of up to 1,700 meters.
The radio communication range of an Ajax device is indicated on the packaging, in the user manual, and on the product page on the official website.
Ensuring the reliability of radio communication in Ajax systems
Automatic power adjustment of the radio transmitter
It is not advisable to use the maximum power of radio transmitters in system devices on a regular basis — this makes the air noisy and increases energy consumption, accelerating the discharge of batteries. An Ajax hub analyzes the signal strength of the connected devices and adjusts the power of their transmitters, taking into account the current radio environment of a facility.
Low noise boards
The selection of quality components minimizes the internal noise of the board and devices.
Event delivery confirmation
The communication between an Ajax hub and system devices is two-way. That’s why, when transmitting an event, alarm, or photo, a detector knows that the packets have been received by a hub, and a hub is informed about the successful receipt of a command by a detector (for example, to change the operation setting). If for some reason, the data is not delivered to the addressee, the sending is repeated until the receipt confirmation is obtained.
Adjustable pings of devices
Ajax allows setting the ping interval of devices by a hub from 12 to 300 seconds. In the case of the minimum interval, a hub needs only 36 seconds to determine if the connection has been lost or if the device has become faulty. Just 0.15 seconds later, a notification of the problem is received by the security company and users.
An Ajax hub/range extender has two multi-directional antennas for Jeweller frequencies oriented at 90 degrees relative to each other.
Hubs with photo verification support have dedicated antennas for Wings frequencies. These antennas are also oriented at an angle of 90 degrees relative to each other.
Radio frequency hopping
Ajax hubs use radio frequency hopping — automatic frequency change within a band according to a specific pattern. This ensures efficient protection against radio interference and signal interception: messages are split into tiny packets that are transmitted at different frequencies. If a packet is not received by the addressee, it is sent on a different frequency when retransmitted. The Ajax system detects jamming of the radio air and notifies the security company and users about it.