In the rapidly evolving world of amateur radio and the Internet of Things (IoT), the ability to communicate over long distances with low power consumption is crucial. LoRa (Long Range) technology has emerged as a popular solution for this need, particularly in applications like Automatic Packet Reporting System (APRS) tracking. This blog post aims to compare two distinct setups for LoRa APRS using VHF (Very High Frequency) and UHF (Ultra High Frequency) frequencies, focusing on their performance in terms of distance and environmental factors.

LoRa APRS VHF Setup

Specifications:

• Frequency: 144.415 MHz
• Spreading Factor: 8
• Bandwidth: 10.4 kHz
• Power Output: 20 dBm
• Coding Rate: 5

Performance:

The VHF setup is particularly suitable for applications in urban and semi-rural environments where line-of-sight may not always be guaranteed. The estimated transmission ranges for this configuration are:

• Best Case (Line of Sight): Approximately 15-20 km
• Semi-Rural Areas: Around 10 km
• Urban Areas: About 3 km

LoRa APRS UHF Setup

Specifications:

• Frequency: 433.400 MHz
• Spreading Factor: 12
• Bandwidth: 125 kHz
• Power Output: 20 dBm
• Coding Rate: 5

Performance:

The UHF setup excels in open environments where line-of-sight is achievable. Its performance metrics are impressive:

• Best Case (Line of Sight): Approximately 40-50 km
• Semi-Rural Areas: Around 20-30 km
• Urban Areas: About 5-10 km

Distance Comparison

In the following chart, we visually compare the maximum distances achieved by both VHF and UHF setups for LoRa APRS. This highlights the significant differences in range capabilities based on frequency and setup parameters.

Transmission Range in Different Environments

The next chart illustrates how both setups perform in various environments: urban, semi-rural, and rural. The VHF setup may have limitations in urban settings, while the UHF setup generally demonstrates superior performance in open spaces.

Important Note

It’s important to note that the distances mentioned in this post are estimations. In real-world scenarios, actual performance may vary due to several factors, including:

• Environmental Obstructions: Buildings, trees, and hills can significantly impact signal propagation.
• Interference: Other electronic devices operating on similar frequencies can cause interference and degrade performance.
• Antenna Quality: The type and placement of antennas can affect the transmission range and signal quality.
• Terrain: Variations in terrain can influence signal strength, with hilly or uneven ground potentially reducing effective range.
• Weather Conditions: Rain, humidity, and other weather conditions can also affect radio wave propagation.

Conclusion

When choosing between VHF and UHF for LoRa APRS tracking, consider the following:

• VHF is advantageous in areas with obstructions such as buildings or hills but has a more limited range.
• UHF provides extended distance capabilities, particularly beneficial in open or less obstructed environments.

Ultimately, the decision depends on your specific needs, environmental conditions, and the operational context of your LoRa APRS tracking applications.