Report of the Committee on Ballistic Acoustics (1982) / Chapter Skim
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APPENDIX D POSSIBILITY OF SUPERPOSED RECORDINGS
APPENDIX D POSSIBILITY OF SUPERPOSED RECORDINGS
Pages 81-88
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From page 81... ...
compatibility of "hold everything..." timing with other firmly established evidence, and (4) recorded acoustic evidence on the recordings such as the characteristics which show that the recorded cross talk passed through a radio receiver with automatic gain control (AGC)
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From page 82... ...
Comparable difficulties confront the hypothesis that there was an accidental superposed recording at a later time. In that case, the Dictaphone playing potential evidence of a presidential assassination would have had to be carelessly set to record instead of listen, and a recording use the print version of this publication as the authoritative version for attribution.
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From page 83... ...
Please APPENDIX D 83 of Channel II at the same time would have had to be playing accidentally in the background. In addition the Channel II playing would have had to be set accidentally to the very narrow range that could indicate incompatibility; if the setting had occurred one minute earlier it would have produced no problem and one minute later it would have been detectable as an impossible timing.
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From page 84... ...
Since the "hold everything..." expression on Channel II occurs approximately one minute after the expression "Go to the hospital...," hence, more than one minute after the assassination, and since the Channel I recorder ran continuously during much of the subsequent time, the cross correlation between the two channels has implications for the timing of some other events following the assassination. Some of this other evidence is unreliable, but some is firmly established.
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From page 85... ...
The last time announcement on Channel I before the conjectured shots and the "hold everything..." statement was "12:28" and the first time announcement thereafter was "12:34," a nominal difference of six minutes. When the Channel I recording is run at a speed that reproduces the recorded hum at 60 Hz, the elapsed time between these two announcements is 389 seconds or 6 minutes 29 seconds in full agreement with the six minute nominal difference, since the time announcements were at irregular intervals and never included seconds.
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From page 86... ...
Whatever behavior there was of AGC on Channel II is reflected in the level of the heterodyne on Channel II, and there should be no further distortion of this level by action of AGC on Channel I This analysis demonstrates that cross talk from Channel II was directly recorded onto a Channel I recorder through a radio receiver and use the print version of this publication as the authoritative version for attribution.
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From page 87... ...
If the Channel I recording is made at the actual time, this difference is easily attributed to the sound actuated Channel II recorder having stopped for 2.9 seconds between these two phrases, while the Channel I open microphone recording continued on without interruptioon. This accounts naturally for the 2.9 second difference; but if the Channel II reocording had been later overlaid onto Channel I the timing of the two would normally have been identical, not differing by 2.9 seconds.
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From page 88... ...
As a result of all these considerations, including especially the ones showing that the cross talk passed through a radio receiver with AGC, the Committee determined that there was conclusive evidence that the "hold everything..." expression was recorded on Channel I at the same time as on Channel II and that the acoustic impulses attributed to gunshots were recorded well after the President was shot and the motorcade had been instructed to go to the hospital. use the print version of this publication as the authoritative version for attribution.
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