B757 PLT REPORTS RECURRING GS OSCILLATIONS FOR ILS RWY 10 AT BWI.

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THE GLIDESLOPE SEEMED TO OSCILLATE UP AND DOWN A BIT BETWEEN 450 FT OR SO AND CLOSE TO TOUCHDOWN; ONLY ABOUT 1/4 OR SO; BUT DEFINITELY SEEMED TO HAVE INTERFERENCE. I ONLY WRITE THIS UP BECAUSE I HAVE CONSISTENTLY SEEN HIGHER FREQUENCY OSCILLATIONS OF THE GLIDESLOPE ON RWY 10 ILS; AROUND 200-100 FEET; REGARDLESS OF WEATHER; USUALLY IN THE EVENING. I'VE BEEN FLYING OFF/ON FROM BWI FOR 3 AND A HALF YEARS. RWY 10 OFTEN DISPLAYS GLIDESCOPE OSCILLATIONS; AND TONIGHT I NOTICED RWY 33L ALSO MOVING AROUND; ALBEIT AT A HIGHER ALTITUDE AND A LOWER FREQUENCY CYCLE. IS THERE ANY CHANCE ALL THE RADIATION FROM A COMMERCIAL FACILITY IS INTERFERING WITH THE SIGNALS? I THINK RWY 10 IS A CAT II/III; AND I WOULD HATE TO SHOOT ONE WITH THOSE DEVIATIONS.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT THE GS OSCILLATIONS FOR THE ILS RWY 33L WERE NOT AS PRONOUNCED AND FREQUENT AS THOSE ENCOUNTERED ON APCH TO RWY 10. HE HAS CONSISTENTLY EXPERIENCED GS OSCILLATIONS AFFECTING RAW DATA DISPLAYS FOR ILS RWY 10. THE GS SEEMS TO OSCILLATE AT THE RATE OF 2 PER SECOND WITH A 1/2 DOT DEVIATION. THE FLT DIRECTOR AND AUTOPILOT ARE UNAFFECTED BY THESE OSCILLATIONS. THE OSCILLATIONS WERE ENCOUNTERED ON NUMEROUS B757'S FLOWN INTO BWI BY THE REPORTER AND OCCUR BELOW 300 FT AGL.