Analyzing long lat location data to find locations in proximity

I am looking for a tool to analyze location data (long lat values from vehicle GPS available). The goal is to identify locations which are in close proximity (within a circle of 30-60ft) and then average values which are assigned to the different locations. Background is that it should be the same GPS values every time since the vehicle is visiting the same location but due to inaccuracies of the GPS the location slightly varies. I am trying to identify the location data which belongs to the same location. Any suggestions?

PS: First time user, let me know if you need more information.

Adding example data for clarification:

1. long lat date reading


2. 32...-81.. 1/19/2015 167


3. 32...-81.. 1/20/2015 345


4. 32...-81.. 1/22/2015 556


5. 32...-81.. 1/25/2015 597


6. 32...-81.. 1/28/2015 658


7. 32...-81.. 1/30/2015 298

Is there software available which could group the locations in above example according to proximity (for example group all locations which are within 30-60ft) and then compute the average of the readings?