Testing a LoRa Module's Real-World Range with a Camera Speedlight

Long-range technology, specifically LoRa (long-range), has gained significant attention in IoT applications due to its ability to transmit data over long distances without requiring internet access. This technology offers a range of advantages, including low power consumption and the potential for remote control of devices from miles away. In this article, we explore how far a LoRa module can actually reach using a simple yet effective setup: a Bluetooth Nugget and a camera speedlight.

The Basics of 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.

Why LoRa Matters

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 and security-focused projects. Its ability to send signals over long distances makes it useful for remote control applications, such as controlling devices from miles away.

The Experiment

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.

The Setup

To recreate this experiment, you'll need the following components:

  • CircuitPython script
  • RFM95W LoRa radio module
  • Camera speedlight with a remote trigger
  • 5-volt DC relay module (one channel)

The setup was tested on a workbench, and initial results showed that the system functioned as expected. However, real-world performance needed to be evaluated.

The Results

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 continued to trigger.
  • Five city blocks: The signal started to weaken, but still managed to trigger the flash.
  • Six city blocks: The signal became too weak to trigger the flash.

The Takeaway

Despite urban environments typically reducing LoRa's range due to obstacles like buildings and signal congestion, 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.