Iím running insider on my notebook (Dell Inspiron 9400) to watch the performance of our WLAN (WRT54GL).

I see lots of RSSI bursts from distant neighboring networks to RSSI = 0 dBm every few minutes. What does this mean? I cannot believe that this are really bursts of signal intensity. Rather I would assume that the signal intensity was lost at all or fell beneath some threshold. But whatís the difference than to signals that simply fade away?