Subject: Inquiry About Maximum and Minimum Distance Measurement Range for Ebyte E73-2G4M08S1C

[Usha]

Dear Nordic Semiconductor Support Team,

I am using the Ebyte E73-2G4M08S1C module, which is based on the nRF52840 chip, for distance measurement purposes. I would like to know:

1. What is the maximum and minimum measurable distance range supported by this module?

2. Are there any specific conditions or limitations (e.g., environment, antenna type, signal quality) that affect the range accuracy?

Your support and clarification would be greatly appreciated.

[tesc]

Hi,

Unfortunately we do not have numbers for specific modules.

In general, the Nordic Distance Measurement library provides accuracy within 0.5 m, from 0 distance up to the range of 1 mbit RF communication (typically several tens of meters) in the case of round trip time (RTT) based measurement. Exact upper bound depend on the environment. Tests in an office environment have shown good results up to the maximum tested range of 20 meters also for phase based distance measurement, although we see some degradation for phase based as we approach 20 meters.

Distance measurement may fail in bad RF conditions, which lead to too few or too poor data points. E.g. due to interference, packet collisions, high noise floor, multipath, etc. Such conditions will affect all radio communication, including the packets sent as part of distance measurement. The risk of failed measurements increases as the distance between the devices increases, and otherwise as radio transmission conditions worsens between the devices.

In addition, reflected signals may lead to wrong (too long) measurements in situations where there is no direct path (no direct line of sight) between the devices. In such situations, the measurement may be that of the reflected path, instead of the physical distance between the devices (since the direct line is blocked and therefore not measurable.)

Ranges and quality of measurements for a given module depend on the characteristics of the given module, but should be proportional to achievable range for the given module over other 1 mbit RF protocols (such as e.g. BLE).

Regards,
Terje