By the way, if you manage to massage your data into a comma-separated file like Dutch did, try this: put the SNR in its own column with no brackets; label that field "N"; save it as a file whose name ends in ".csv"; and try this form:
http://www.gpsvisualizer.com/map?form=data
The gimmick here is that the "N" field determines the SIZE of the waypoints; points with a stronger signal will appear larger than weak signals. It's not well documented yet, though; suffice to say the calculation is done differently if the minimum waypoint size is set to zero than if it's set to a number greater than zero.