RC Circuit? Confirm my educated guess

[cbassett1000]

Below I have an ASCII schematic I am trying to figure out what it does, specifically to the signal wires.  I am thinking some sort of RC circuit, maybe a band pass filter of sorts? It does not affect the signal when measuring DC, AC measurement has not been tested.  The circuit goes parallel into the S1 and S2 wires.  S1 and S2 are DC leads (less than 20 volts) but *may* have AC noise in them. S1 and S2 may or may not be floating reference to ground.  I cannot give much further information due to NDA. Thanks!

|||S1-Signal Positive/S2-Signal Negative/R1-20.5k/R2-500k/C1-1uF/C2-2uF|||  || "T"-Obvious/"+" 4 point junction/"L" Elbow ||

T
|                      T
S1                  S2
|                      |
|--R1--C1--R1--|
|--R1--C1--R1--|
|                      |
|--R2---T---R2--|                   Middle of R2s and C2s are connected directly to earth.
L--C2---+--C2--L
    Earth/GND

[cbassett1000]

Bump. Anyone?