Recently, I saw a newcomer's post on Twitter regarding his first WSJT-X session. I noticed right away that he only decoded a handful of stations, but those with supposedly extremely good reports. This is what happens when you set your receive bandwidth extremely low. This means that you only receive signals that lie within this range. If we remember again our education, we find out that a normal report refers to a bandwidth of 2.5kHz. In this articel I explain the fundamentals about that.