beDMX Protocol Based on Bluetooth for Wireless DMX Transmission

In wireless lighting control systems, a console generates the DMX signal and transmits it via cable to a radio transmitter. This transmitter then broadcasts the signal over a radio channel to a receiving device, which converts it back into a DMX signal to control lighting fixtures, typically delivering it through a wired connection.

Wireless modules enable DMX signal transmission from point "A" to multiple points such as "B," "C," and beyond, bypassing obstacles that render cable installation impractical.

This solution is particularly valuable for dynamic stage setups, such as rotating theater stages where a movable circle spins around an axis. Power is supplied to the rotating section via slip rings or brush contacts, but transmitting the DMX signal through cables introduces additional complexities.

DMX networks are inherently intricate, involving numerous devices that demand careful planning and installation of cable lines. These lines require proper termination, load distribution, and specialized cables and connectors, making radio systems an optimal choice. Radio transmitters also expedite the deployment of lighting systems when laying long cables is impractical.

However, for large-scale events like concerts by renowned artists, where precise synchronization of lighting with music, vocals, and choreography is essential, radio signal transmission may lack sufficient reliability. Even minor disruptions in the lighting scene can lead to significant consequences, making wired connections preferable in such cases.

Founded in 1876, Ericsson initially focused on manufacturing railway and military field telephones, as well as repairing telegraph and signaling equipment. The Swedish company expanded its operations, supplying network equipment to neighboring countries, cities within the Russian Empire, and overseas markets.

The early 1990s marked a surge in mobile phone popularity. Ericsson Mobile, a market leader, sought to enhance the functionality of its devices.

The Bluetooth concept originated with Nils Rydbeck, Ericsson’s technical director, who in 1994 tasked engineer Jaap Haartsen with developing a short-range wireless technology for transmitting voice and data between electronic devices. Existing solutions failed to meet all specified criteria, which included direct connectivity, simultaneous voice and data transmission, and low power consumption. Other technologies Haartsen explored also fell short.

A pivotal moment occurred at the IEEE conference in The Hague, where Haartsen attended symposia on communications and wireless PC networks. In 1995, he was joined by Sven Mattisson, a Swedish wireless technology specialist.

That same year, Ericsson began developing short-range radio communication technology. To ensure compatibility and broader adoption, collaboration with other companies was necessary. In 1998, Ericsson, Intel, IBM, Nokia, and Toshiba established the Bluetooth Special Interest Group (SIG) to standardize the technology.

Nokia improved Bluetooth integration with mobile devices, Toshiba ensured hardware compatibility with computers, and IBM standardized protocols, transforming Bluetooth into a universal platform.

Jim Kardach from Intel suggested naming the technology "Bluetooth," inspired by the 10th-century Danish king Harald I Bluetooth. Just as the king unified disparate Danish tribes into a single kingdom, Bluetooth technology aimed to unite the diverse realms of PCs and mobile communications into a seamless wireless ecosystem. It was envisioned as a bridge connecting various communication protocols into a universal standard, erasing boundaries between devices and creating a digital kingdom.

The king earned his nickname from a dark front tooth—"Blåtand" in Danish. While the modern Scandinavian "blå" translates to "blue," in Viking times it meant "black," likely reflecting the tooth’s actual color. Given the challenges of navigation, warfare, and raids during that era, it’s plausible that Viking dental health was poor, supporting the notion of a darkened tooth.

Initially intended as a temporary name, "Bluetooth" persisted when alternatives like "RadioWire" and "PAN" were rejected due to their common usage online. The adage that nothing is more permanent than a temporary solution proved true, and the technology retained its original name and embedded meaning.

The Bluetooth logo, now a recognized symbol of wireless communication, combines two Scandinavian runes: Hagall ᚼ and Berkana ᛒ, representing the initials of King Harald Bluetooth (Harald Blåtand).

The Bluetooth transmitter for DMX signals supports data transmission rates up to 3 Mbps, operates across 79 radio channels, and detects signals on 32 channels.

Bluetooth technology relies on Frequency-Hopping Spread Spectrum (FHSS), operating in the 2.4 GHz band, which is divided into multiple sub-frequencies. Bluetooth devices continuously switch between these sub-frequencies, causing the signal to resemble noise on a spectrum analyzer.

The core of Bluetooth networking is the piconet, which connects one master device to up to seven active slave devices. For wireless DMX transmission, a minimum of two devices is required—a transmitter and a receiver—arranged in a star topology.

Bluetooth utilizes the 2.4 GHz band, segmented into 79 sub-frequencies, employing rapid frequency hopping to minimize interference. For example, one device pair might hop between frequencies 1, 20, and 31, while another uses 2, 38, and 49.

Each piconet follows a unique hopping sequence, operating on its own dynamically shifting frequency, which reduces signal overlap. This makes wireless DMX transmission via Bluetooth resistant to interference, as each device pair uses a distinct hopping pattern unknown to others, allowing multiple Bluetooth groups to function in close proximity.

Data packets are transmitted in segments across different frequencies, and only the intended receiver can reassemble them, enhancing security against interception.

Our devices go beyond basic frequency hopping by actively analyzing the airwaves to identify interference.

The beDMX protocol incorporates Adaptive Frequency Hopping (AFH), enabling devices to automatically select clear radio channels and avoid interference. beDMX devices switch frequencies approximately 1000 times per second. For instance, if the third frequency exhibits a poor signal, the system excludes it from the hopping sequence, shifting to another frequency to ensure uninterrupted transmission. This process applies to any problematic frequency.

Known as adaptive hopping, this mechanism relies on constant spectrum probing. beDMX devices assess transmission quality with each frequency hop, occurring every millisecond. Simplified, hops follow a table of suitable frequencies, with the next frequency calculated using the CRC32 algorithm: an initial value of 0xFFFFFFFF is updated based on the previous CRC32, determining the index of stored frequencies. If a frequency is noisy, the transmitter sends a SYNC_COMMAND, including the current CRC and a list of "good" frequencies, to synchronize receivers and confirm their presence. Receivers either acknowledge the connection or, after 20 unresponsive attempts, are deemed disconnected, temporarily excluding the problematic frequency. The system later retests these frequencies, updating the list of available channels.

This ensures that Sundrax’s wireless DMX systems, comprising multiple piconets, operate flawlessly. Each piconet uses a unique frequency-switching sequence, determined by the transmitter’s address (e.g., 0xDBF51A0CXX for discovery or 0x5C4D90FBXX for transmission) and subnet number, minimizing signal overlap. Jamming such devices would require overwhelming interference across the entire 2.4 GHz band. Localized disruptions, like Wi-Fi or other devices, cannot interrupt transmission, as beDMX instantly shifts to a free frequency.

Active devices maintain continuous two-way communication, exchanging service data with each hop. The transmitter sends SYNC packets to verify receivers, which respond by aligning their timers to its rhythm. This synchronization enables rapid responses to airwave changes. For example, if a receiver fails to respond, the transmitter updates the network status via the BT2_PROT_REQ_STATE request, providing the central controller with real-time buffer and device connection data. Unlike low-quality, fixed-frequency solutions, beDMX delivers high reliability and interference resistance through dynamic adaptation and intelligent frequency management.

Our wireless DMX lighting control solutions are built on Bluetooth technology, utilizing the lower-level HCI protocol, adapted for reliable real-time data transmission. This approach, implemented via a standard communication interface with the Bluetooth controller (UART, 921600 baud), ensures consistent and precise operation in the 2.4 GHz band.

With extensive Bluetooth experience dating back to Ericsson’s earliest chips, we understand that "more" doesn’t always mean "better." 

For example, some manufacturers’ wireless DMX systems may use:

• 81 frequencies instead of 79 to avoid interference, but exceeding the standard 2400–2483.5 MHz range can lead to conflicts with other devices. In contrast, beDMX employs AFH, analyzing the spectrum with commands like SYNC_COMMAND and excluding noisy channels from its table of good frequencies, ensuring compatibility with Wi-Fi and other 2.4 GHz devices without unnecessary spectrum expansion.
• Both 2.4 and 2.5 GHz bands instead of adhering strictly to 2.4 GHz, often indicating poor interference suppression. Extending beyond 2483.5 MHz reduces range due to increased signal attenuation. beDMX operates solely in the 2.4 GHz band, achieving up to 1500 meters with directional antennas through strict Bluetooth standard adherence and intelligent hopping via CRC32 calculations, ensuring uninterrupted and predictable performance even under heavy RF loads.

Devices like RadioGate Arma further enhance reliability with two-way communication: transmitters and receivers exchange service data every millisecond, synchronizing timers and monitoring network status.

Though often associated with short-range applications, Bluetooth can connect devices over significant distances, depending on the transmitter’s power class:

Class 3: Less than 5 meters (e.g., wearable electronics)

Class 2: 10-20 meters (e.g., mobile devices)

Class 1: 100-200 meters (e.g., DMX transmission devices)

Range diminishes with obstacles like scenery, walls, or trees, and signal reflection from buildings further reduces it.

In show environments with walls, partitions, and numerous devices, ideal transmission conditions are rare. Thus, planning a wireless DMX system requires equipment with sufficient range reserves to account for these factors.

Sundrax devices offer range flexibility with detachable RP-SMA antennas. Standard omnidirectional whip antennas provide reliable coverage up to 200 meters, suitable for medium-sized areas without additional components.

For greater distances, these can be swapped for panel antennas (up to 1.5-2 km) or highly directional Yagi antennas (potentially up to 5 km under ideal conditions). beDMX enhances range through two-way synchronization, with transmitters and receivers exchanging service data every millisecond to maintain stability even at extreme distances. Directional antennas are available upon order, allowing system optimization for any application.

Standard single-channel devices transmit DMX signals unidirectionally from transmitter to receiver. Our transceivers, however, can operate in both transmit and receive modes, switchable via buttons on the device housings.

For example, a system with one transmitter and three receivers can use a set of four devices—one as the transmitter and three as receivers—or two separate transmitter-receiver pairs.

This flexibility simplifies configuration, especially for rental applications where setups vary between events. With Sundrax devices, users can unbox and configure them in any required arrangement, and the devices automatically identify optimal frequencies.

Device pairing is managed via buttons on the housings. The master device (transmitter) enters search mode, broadcasting a signal on subnet 0xFF to detect all receivers. Receivers in PAIRING mode flash their indicators and transmit their ID, type, and function details. Upon user confirmation, selected slaves join the master, forming a group on the designated subnet.

Some receivers, not actively transmitting data, remain within the master’s range and periodically receive SYNC_COMMAND packets to synchronize their timers with the transmitter. This allows rapid activation when needed, maintaining network connectivity even in standby.

A single master can connect to 64 slave receivers, with the group persisting across sessions. Devices exchange a table of good frequencies via SYNC_COMMAND, excluding noisy channels. Each group uses a unique, CRC32-calculated hopping sequence on its subnet, enabling multiple groups to coexist without interference. Frequency-time division is maintained by millisecond-level frequency switching, synchronized by the master.

Each device features connection status indicators, leveraging the RDM protocol to display connected devices and their count. The master receives slave status data (including RSSI), enabling visual monitoring of communication quality. LED indicators provide comprehensive feedback: a receiver’s flashing light confirms connectivity, with indication available in both operating modes, streamlining deployment, configuration, and maintenance.

RadioGate: Wireless DMX transceivers with beDMX technology on Bluetooth, ensuring reliable signal transmission. The Arma model, designed for outdoor and open-area use, features a waterproof metal housing (IP65)—the most compact in its class, unlike competitors’ bulkier plastic designs. The Solid model suits indoor surface mounting.

RadioGate Plus: Hybrid devices in Arma and Solid housings, integrating Art-Net/sACN-to-DMX conversion, DMX splitting/boosting, and beDMX wireless transmission. This minimizes equipment needs in complex lighting setups, supporting both wired and wireless protocols.

LEDGate Wireless: Wireless drivers for advanced PWM LED control, delivering flicker-free dimming and short-circuit protection. Available in Compact housing or as a board for flexible integration.

Unlike the versatile Bluetooth standard, beDMX is a specialized, patented protocol from Sundrax, optimized for wireless DMX transmission in demanding conditions. It transmits data in 64-byte buffers, ideal for DMX’s 512-byte universe (divided into eight buffers).

beDMX harnesses Bluetooth 5.0’s high-speed and interference-resistant capabilities, augmented by unique features. Adaptive Frequency Hopping (AFH) with CRC32-calculated sequences and millisecond synchronization ensures instant interference adaptation. Two-way RDM support facilitates both data transmission and device management.

We recognize lighting as a vital, expressive, and captivating tool for designers. From cozy urban holiday displays to massive music festivals, theater productions, and architectural illumination, beDMX empowers creators to realize bold visions without constraints. With our equipment, light shines in every color and shade, wherever you are.