Any alternatives to GHA15 radar altimeter?

[RV14_TD]

Are there any alternatives to the GHA15 radar altimeter, I mean a proper Radar altimeter not Lidar based device?

 

[airguy]

There have been a few folks talking about building there own some years back, that's well above my level of electronics so I can't tell you more about than that I heard it was happening. I don't believe there is an "off-the-shelf" alternative.