Quote from GeoAstra Official on July 30, 2024, 9:25 am

In most scenarios, it is acceptable to use an L1 and L2 antenna with an L1, L2, and L5 GNSS receiver. Here’s why:

Additional Signal and Anti-Interference Capabilities of the L5 Band

The L5 band (1176.45 MHz) is the third civil GPS band, designed to provide stronger signals, higher accuracy, and better anti-interference and multipath capabilities. The advantages of the L5 band include:

1. Signal Strength: L5 signals are stronger than L1 and L2 signals, allowing better penetration through the atmosphere and buildings, resulting in more stable signal reception.

2. Bandwidth: The L5 signal has a wider bandwidth (10 MHz), providing better signal resolution and accuracy.

3. Anti-Interference Capability: The coding and modulation of the L5 signal enhance its ability to resist interference and multipath effects, making it perform better in complex environments.

4. Safety and Reliability: L5 signals are designed for safety-critical applications, offering higher reliability.

High-Precision Positioning of L1 and L2 Bands in RTK Applications

Despite the advantages of the L5 signal, the L1 and L2 bands have been successfully used for high-precision RTK positioning for many years. Key benefits include:

1. Mature Technology and Wide Application: L1 and L2 signals are widely used in GNSS systems, and the corresponding receiver technologies and algorithms are well-established.

2. Dual-Frequency Phase Difference Measurement: RTK technology relies on phase difference measurements of L1 and L2 signals for high-precision positioning, effectively eliminating ionospheric delay errors, thereby providing centimeter-level positioning accuracy.

3. Device Compatibility: Most existing GNSS receivers and antennas support the L1 and L2 bands, making device selection and compatibility broader.

Multipath Effects and Interference

In practical applications, interference and multipath effects can affect GNSS signal quality. Multipath effects occur when signals reflect and refract before reaching the receiving antenna, causing multiple paths of signals to superimpose and affect positioning accuracy.

Performance of L1 and L2 Bands

Although the L1 and L2 bands are not as robust as the L5 band in terms of anti-interference and multipath effects, they have provided stable and high-precision RTK positioning in most environments through years of technological advancements and algorithm improvements.

Advantages of the L5 Band

In complex urban or high-interference environments, the stronger signal and anti-interference capability of the L5 band can improve positioning accuracy and reliability. However, for ordinary RTK applications, if the operating environment is relatively open and less prone to interference, the L1 and L2 bands can provide sufficient precision and stability.

Summary

While the L5 band offers additional advantages, for most ordinary RTK applications, the L1 and L2 bands are sufficient to provide high-precision positioning services. If your application environment is not too complex (e.g., without many building obstructions or electronic interference), using L1 and L2 dual-band antennas can fully meet your needs. The advantages of the L5 band only become significant when extremely high precision or operation in complex environments is required.

Furthermore, your L1 and L2 antenna’s frequency response is not absolute; it may have some sensitivity near the L5 band. Although the antenna is primarily designed for the L1 and L2 bands, it can handle a broader frequency range than specified. Even if the antenna’s reception efficiency at the L5 band is lower, the receiver can still extract useful information from the weaker L5 signals.

Therefore, in most scenarios, it is acceptable to use an L1 and L2 antenna with an L1, L2, and L5 GNSS receiver.