UFOINTEL
Radar Report
Unclassified Complete
733667-001-019-0178
National Archives and Records Administration
Confidence
85%
Credibility
80%
View original document ↗ hosted at the official government source
Intelligence summary
The document discusses the phenomenon of uncorrelated radar signals, explaining the differences between primary and secondary radar returns and how they can indicate the presence of an aircraft.
Tags & topics
Extracted timeline
Jun 15, 1987
Document Date (year hint)
Document Date (year hint) for 733667-001-019-0178
Jun 16, 2026
Ingestion Date
Ingestion Date for 733667-001-019-0178
Jun 16, 2026
Document Record Date
Document Record Date for 733667-001-019-0178
Jun 16, 2026
Update Date
Update Date for 733667-001-019-0178
Entities mentioned
Full document text
792 characters, transcribed via OCR. Errors reflect the source scan. Compare with the original ↗
i
UNCORRELATED RADAR SIGNALS
An “uncorrelated primary and beacon(secondary) return on a radar
screen occurs when the radar energy that is sent up toward the aircraft
(primary signal) returns off the surface of the aircraft at a slightly
different moment than the beacon (secondary) transponder signal and the
two do not match up as being at the same place or same computer radar
cell.
--RADAR COMPUTER CELL, 1/4 MELE~- . “RADAR CELL
i SAME AIRCRAFT |
a X\ (Crossj{ng Cell)
—T
- = ¥ — as
Ti Ujp-——ae UY YY
SECONDARY ~< Se 4
C RADAR = ype
a RETURN
3 (Beacon)
' (Transponder)
WN
PRIMARY
RADAR
RETURN
(Skin-
Surface)
VY
(+ » =PRIMARY RADAR RETURN
(N) =SECONDARY RADAR RETURN
| - ; =CORRELATED RETURN
(Combined Return)
Drawing by Paul Steucke . .
March 5, 1987 ~~ é =UNCORRELATED RETURN