- Sakharov
- Jun 30
- 1 min read
We have updated the ITU-R P.1812 propagation model to the latest version, P.1812-8. The update includes the ability to choose between the Deygout method (used in earlier versions of Recommendation P.1812) and the Delta-Bullington method (used in the latest versions of Recommendation P.1812) for diffraction loss calculations. This allows users to calculate coverage areas more accurately by taking terrain characteristics into account.
The table below summarizes the conditions under which each diffraction loss calculation method is preferred.
Condition | Deygout method advantage | Delta-Bullington method advantage |
Several sharp terrain obstacles (multiple knife edges) | ✅ Better — identifies the dominant obstacle and recursively accounts for secondary obstacles | May simplify the path too aggressively |
One dominant ridge with smaller surrounding obstacles | ✅ Often more accurate | Usually gives similar results |
Deep shadow regions behind mountains/ridges | ✅ Better representation of multiple-edge diffraction | Can underestimate or smooth losses |
Smooth terrain with no clear dominant obstacle | Little advantage | ✅ More stable and realistic |
Long paths with many small hills | Often overestimates because it treats secondary edges recursively | ✅ Better average prediction |
Mixed terrain with irregular clutter | Limited benefit | ✅ More suitable |
