What min altitude do you fly for 1,2,3, etc km flights?

[R0v3r2020]

I find I get a video warning signal pretty soon, at perhaps 500-1000k distance when only at 30+ meters altitude. If fly higher the video signal warning ceases.
what altitudes have you found you need to maintain strong video signal connection with your craft on 2+km flights?

 

[Ansia]

I am guessing you mean 500-1000 meters. If you are flying as low as 30m high, then you will have obstacles along the way that degrade your signal. When you gain altitude, these obstacles are no longer in your way.