Controller states that d-brite occasionally shows numerous phantom primary targets.

Attributes
ACN	256922
Time
Date	199311
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dpa
State Reference	IL
Altitude	agl bound lower : 0 agl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dpa tower : mxp
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Experience	controller non radar : 4
ASRS Report	256922
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

While working local control, I observed numerous primary targets appearing and disappearing throughout dpa class D surface area. I advised C90 that there appeared to be 'phantom' primary targets in different quadrants of our surface area, the controller acknowledged and said they also saw them. This continued to happen throughout the rest of my shift. This wasn't the first time I've seen this, after discussing this with several other ATC's here I realized this is a recurring problem.

Original NASA ASRS Text

Title: CTLR STATES THAT D-BRITE OCCASIONALLY SHOWS NUMEROUS PHANTOM PRIMARY TARGETS.

Narrative: WHILE WORKING LCL CTL, I OBSERVED NUMEROUS PRIMARY TARGETS APPEARING AND DISAPPEARING THROUGHOUT DPA CLASS D SURFACE AREA. I ADVISED C90 THAT THERE APPEARED TO BE 'PHANTOM' PRIMARY TARGETS IN DIFFERENT QUADRANTS OF OUR SURFACE AREA, THE CTLR ACKNOWLEDGED AND SAID THEY ALSO SAW THEM. THIS CONTINUED TO HAPPEN THROUGHOUT THE REST OF MY SHIFT. THIS WASN'T THE FIRST TIME I'VE SEEN THIS, AFTER DISCUSSING THIS WITH SEVERAL OTHER ATC'S HERE I REALIZED THIS IS A RECURRING PROB.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.