2018-06-04 23:42:57 UTC
The link is to a scale map of Dealey Plaza. The map was made by
reflecting the Drommer Topographic Survey about the center of Main
Street. The Post Office is seen in the bottom of the map. Doing this
allows one to calculate an accurate measurement of the delay time of an
echo from the Post Office. (about 720 ms)
On the right side of the map are two strip charts. The strip charts show
the two interpretations for the location of the knoll shot impulses on
the Berkovitz tape, which is a replica of the BBN tape, which is the
tape to which BBN applied the adaptive filter.
The top strip chart shows the initial interpretation for the knoll shot
impulses. BBN obtained this location by using a match filter, which
means, they matched the echo pattern from an test shot fired from the
knoll to the impulse pattern on the tape. When they did this they got a
.8 correlation coefficient.
The bottom chart is the location on the tape where Weiss and Aschkenasy
located the impulses for the knoll shot. They moved the knoll shot
impulses "upstream" about 250 milliseconds from where BBN obtained their
pattern match. W&A used a different method, echo correlation, to
determine the location for the knoll shot impulses.
The map on the left shows the impulses relative to the W&A
interpretation. The shooter is located where W&A put him and the
microphone is located 97 feet south and 27 feet east of the corner of
the TSBD, which is where W&A located the open microphone.
The problem for the W&A interpretation is the packet of impulses in red.
In the BBN interpretaton those impulses are associated with a reflection
from the west wall of the county records building. However, in the W&A
interpretation, those impulses have been abandoned. W&A did not show
those impulses in their report. They ignored them. Today we have the
Berkovitz file, and we know about those impulses colored red.
The question is, relative to the W&A interpretaton, what do those
impulses colored red represent? They do not match an echo from the Post
Office. In fact, when placed on the map, they do not appear to match any
structure in Dealey Plaza. Does this mean that we should not interpret
them as an echo in the W&A interpretation? Or does it mean that the W&A
interpretation is wrong and the the correct location for the impulses on
the tape was given by BBN in their initial location for the knoll
impulses(the top strip chart)?
Special note to Marsh. March I will take the time to explain this to you
but only on two conditions
1)You keep an open mind (no knee-jerk reactions) and
2)You inform Don Thomas about W&A's abandoned impulses.
From the odell discussions and the strip charts you should have figured
out that there is a tape out there that is a copy of the tape to which BBN
applied the adaptive filter. It is the best version of the tape because it
has the least amount of noise. It is the tape from which W&A did their
measurements. Why you do not have it is a mystery to me, Don Thomas has it
and I would think that he would have given you a copy. Michael ODell has a
copy and I have a copy. I would suggest that you ask Don Thomas for a
copy. Once you get the copy I will help you orient yourself on that tape.
Anyone who is going to analyze the W&A interpretation PROPERLY, should
have a copy of that tape. You need this tape (and a means to display it
and work with it) in order to properly analyze the W&A interpretation.