The data was collected with my HDS at high quality. DrDepth can use the data collected at low quality but I always record on high because we have lots of cheap memory on the SD cards and lots of memory on the computer hard drives. The higher quality allows a clearer picture if you want to study them in the HDS simulator, the computer emulator (coming someday from Lowrance) or the SonarViewer (a new one is coming someday from Lowrance). All of these tools will re-play your logged files just like a DVD player.
I was amazed at the accuracy the DrDepth BT Edition creates bottom hardness maps. I was too focused on tournaments this year to collect data to experiment with; I will be more alert next year!