When the NX-class starship Enterprise discovered an Axanar vessel in 2151, the Starfleet crew sent a pulsar grid to the alien ship. The grid showed the location of the Sol system.(ENT: "Fight or Flight")
Background information Edit
While never pointed out as such, a map showing the location of Earth using this method was included on the Pioneer 10 probe, seen in Star Trek V: The Final Frontier, and the same plaque was also in the memory banks of V'ger.