Signal Level just tells you that some signal voltage is coming from the LNB to the receiver. If you have a 94 Signal Level and then put your hand over the front of the LNB so no satellite signal is being received from the dish, your Signal Level will probably still be in the 90s because there is always a signal voltage coming from the LNB. Basically, Signal Level tells you there is an LNB connected and working. Signal Quality will tell you that a recieved satellite signal is present and being decoded (if the parameters on the receiver are set properly). The higher the Signal Quality, the more data is being received without having to use data correction methods (better signal). The lower the Signal Quality, the more data correction methods are used to maintain a picture. Of course, there comes a point that the Signal Quality is so low (amount of good data received) that the receiver can't correct all the data errors and the picture suffers. Hope this helps. Have fun.