LoRa (long-range) technology is widely used in IoT applications because it can transmit data over long distances without requiring internet access. Because of its long range and low power consumption, LoRa can be used to remotely control devices — even from miles away. Hackers and security researchers have experimented with LoRa for everything from remote payload activation to off-grid communications. In this test, we explore how far LoRa can actually reach using a simple but effective setup: a Bluetooth Nugget and a camera speedlight.
Understanding LoRa technology
LoRa operates in the sub-gigahertz frequency range, offering a significantly greater range than Wi-Fi or Bluetooth at the cost of bandwidth. Unlike Wi-Fi, which typically operates at 2.4 GHz or 5 GHz, LoRa uses lower frequencies to achieve long-distance communication. The actual transmission frequency varies depending on your region, so it's essential to check legal operating frequencies before using LoRa devices.
In addition to point-to-point communication, LoRa can also be used for mesh networking, where multiple devices relay signals to extend coverage beyond a single transmitter's range. One popular project that leverages this is Meshtastic, an open-source communication platform that enables long-distance, off-grid messaging by turning LoRa radios into a distributed network. While our experiment focuses on direct device-to-device communication, similar setups could be used to integrate LoRa into a larger mesh system.
One of LoRa's most significant advantages is its low power consumption, making it ideal for IoT applications like sensor networks and remote monitoring. LoRa itself is a radio modulation technology that allows long-range communication without relying on Wi-Fi or cellular networks. LoRa communication can function independently in peer-to-peer setups, but larger networks often rely on LoRaWAN integration for internet connectivity. In the US, LoRa operates license-free, making it an attractive choice for experimentation.
The experimental setup
In this experiment, a LoRa module was added to a Bluetooth Nugget, allowing real-time signal strength monitoring via an OLED display. Instead of traditional range testing, the goal was to trigger a camera speedlight upon receiving a LoRa signal. This provided a visible confirmation of signal reception, making it easy to gauge the technology's effective range in an urban environment.
LoRa's ability to send signals over long distances makes it useful for remote control applications. In a security context, LoRa has been explored for remotely triggering devices, automating IoT systems, and even creating covert communication networks. While our experiment focuses on range testing, the same principles apply to controlling other devices remotely using LoRa.
To check whether a LoRa module is actively transmitting, you could use tools like a software-defined radio (SDR) or a Flipper Zero to detect signal activity. While an SDR provides a more detailed look at transmissions, a Flipper Zero can be tuned to the same frequency for a quick confirmation, though it cannot fully decode LoRa's spread-spectrum modulation.
The speedlight was triggered by shorting its remote trigger port using a relay controlled by the LoRa module. A simple CircuitPython script ran on the Bluetooth Nugget, listening for incoming LoRa packets. Upon receiving a packet, the GPIO pin activated the relay, triggering the speedlight.
Video walkthrough:
Products used
To recreate this experiment, you'll need the CircuitPython script and:
RFM95W LoRa radio module, such as:
Real-world testing
Initial testing on a workbench confirmed that the setup functioned as expected. However, real-world performance needed to be evaluated. The test site chosen was a pedestrian bridge with a clear view of a long downtown street — an ideal location for assessing range in an urban environment.
The first test was conducted at one city block, approximately 100 meters away. The flash was successfully triggered, confirming that the system was operational. After moving to two city blocks, the LoRa module maintained connectivity, with the flash consistently responding to signals.
To push the limits of our build, we continued the test at increasing distances:
Four city blocks: The signal remained strong, and the flash triggered reliably.
Six city blocks: Connectivity began to degrade, with some missed signals, but it was still functional.
One mile away: At this distance, the LoRa module struggled, and the flash no longer responded. This indicated that the effective range in this environment was just under a mile.
Key takeaways
This experiment demonstrated that LoRa modules can achieve impressive distances even in urban settings with obstacles. LoRa range is affected by multiple factors, including antenna type, power settings, environmental conditions (such as humidity), and RF interference from nearby devices. While LoRa can achieve over 10 km in open areas, urban environments typically reduce this range due to obstacles like buildings and signal congestion. Despite this, the ability to transmit signals nearly a mile in a city environment — without cellular or Wi-Fi — highlights the potential of LoRa for various applications, including emergency communication, remote sensor monitoring, and off-grid networking.
LoRa technology offers exciting possibilities beyond just triggering a camera flash. Whether for IoT applications, long-distance communication, or security-focused projects, LoRa continues to prove itself as a versatile and reliable wireless communication method.
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Cover image by Null Byte.
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