NEW RECEIVING TECHNIQUES PROGRESS DURING JULY 1960 - MARCH 1961

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A001200060016-7
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 39
• Document Creation Date: December 22, 2016
• Document Release Date: February 21, 2012
• Sequence Number: 16
• Publication Date: March 1, 1961
• Content Type: REPORT

Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
f~~
_ _. _.,
^ DECL~ REWV
~YT ~Y D 6 YR$'
REASON
~~-----~--- ~~~~ ~ , __ v.
tie G'o-.l;~tU - - .- ~-
?C~iTa ~~, ~~ a p,D i~~srrt t~iY ~~~3
,>._ ~
Fro jeCt: 8.58 ;
~('C.~i16~~~~~ 1 ~~L
PR4GR~S~iRTRTN G
MARCH l9 61
NEU+T , REG'E'L VING_,TECHNIQU
This is the ninth in a series of monthly letter
reports on a feasibility study to examine the principles
and limitations of the frequency time transformation as
applied to a self adjusting spectrum filter, together with
breadboarding of some critical circuits.
The final report is presently being typed and
will be forwarded daring the next interval.
~.~~ ~ ~.~
Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7 ~
 Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
NEfnF RECEIVING TECHNIQUES
PROGRESS I)CTRING
February 1961
This is the eighth in a series of letter reports on
a feasibility study to examine the principles and limitations
of the frequency time transformation as applied to a self
adjusting spectrum filter, together with breadboarding of some
critical circuits.
,,
The last of the breadboard circuits needed to complete
the system has been finished. The entire system was assembled,
aligned, and compression and dispersion characteristics measured.
In addition tests were made of the effectiveness of amplitude
shaping for sib als of different input frequencies .
In the breadboard system (Figure 1) a 27 Mc input
si gnal is mixed with a 37 Mc swept L.Q. producing a 10 Mc
swept signal which is fed into the first compressive network.
The network output is then mixed successively with a second
37 Mc swept ~.0. and a 53 Mc crystal oscillator to produce
the 6 Mc compressed output. The dispersion process begins with
mixing the 6 Mc output with the second 37 Mc swept L.O. and
inverting with a 33 Mc crystal oscillator to produce the 10 Mc
Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
input to the second compressive filter. The output of this
filter constitutes the dispersed waveform. Actually a third
swept L.O. should follow this filter output to produce a signal
equivalent to the input. Since this mixing would ha v? no effect
on the output amplitude it was not included.
The reason for mixing the compressed output with a
second swept L.O. and then inverting the process by mixing
again with the same L.O. may not be readily apparent. This
was done to allow the insertion of an amplitude shaping network
between the two mixers. If two input signals enter the compression
system they produce similar swept sin x~x outputs differing only
in time of occurrence and center frequency. If an amplitude
shaping network is designed to effectively suppress the side-
lobes of one signal it must have a frequency response centered
at that frequency. Therefore it could not effectively suppress
the sidelobes of one signal it must have a frequency response
centered at that frequency. Therefore it could not effectively
suppress the sidelobes of the second signal. If a second L.O.
is placed before the shaping network, synchronized with the
the first sweep and delayed from it by a time equal to the
average delay through the compressive filter, the center frequencies
of different sin x/x pulses will be the sarne. Thus the amplitude
shaping network will suppress sidelobes on all signals entering
the system. The second mixing process is then necessary to
restore the frequency dependence of the compressed outputs before
beginning the dispersion process.
Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
3-
The 53 Mc and 33 Mc crystal oscillators are used to
invert the compressed output bef ore dispersion. Normally
the network used to disperse the compressed waveform would
have a slope equal and opposite to the slope of the compressive
network. Since both our networks are identical, the same effect
is obtained using the inversion process. This reverses the
frequency spectrum of the compressed waveform and causes it to
be dispersed in the second network.
Tests of both compression and dispersion were made with
three different input frequencies. Figures 2, 3, and 4 show
the compressed outputs for inputs of 26.5, 27.0 and 27.5 Mc.
Figures 5, 6 and 7 show the same outputs with sin x/x shaping
added. Figures 8, g and 10 are the outputs of the dispersive
filter. These photos show there is a great dependence upon the
frequency of the input signal to sidelobe level, with and with-
out shaping. These differences can only b? attributed to
variations in the time delay characteristic. However, the
shaping network gives noticeable improvement of sidelobe
level over most of the frequency band. Output after the
dispersive network shows considerable amplitude variation over
the sweep period which is also dependent upon the input
frequency. Both phase and amplitude variations can cause
this result. The amplitude response of the two networks can
only be compensated within 6 db due to erratic variations of
their amplitude response with frequency. These amplitude
Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
-4-
variations are seen directly in the output. In addition,
phase-errors in the system cause peaks and nulls in the
recombined output.
This completes the major breadboard portion of the
study project. There are a few items of doubtful importance
which may receive some attention, but i t is anticipated that
the main effort from now on will be in assembling the data
and writing a final report.
Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
~.
Sr~N_ t tN
1~ 37mc
~~~pr
M~xE~e
CO,MtPR~sS/
IYFTwoRK
,~ 3 me
X rk~.
?sc.
~iXER
ty
IXER
5'3 nsc
X rAL
Ost.
~!'''K
Gor~e~4FSsFp
O uTpv7-
N~rwdRx aU TPuT-
F~ ~-uR E /
Z'~ 37inc
Swat T
L. D.
~raA
 ? Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
~
A
~
~ ~ ~
~ ~~ ~~~ _
=6
.5 ~,~
FIGURE 3
27.0 Mc
FIGURE L~.
'~
27.5 Mc
-- Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
FIGURE 8
26.5 Mc
Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
NE~~T RECEIVING ^1ECIIl\TIQUES
PROGRESS I~TRING
January 1961
This is the seventh in a series of letter reports on
a feasibility study 'to examine the principles and limitations
of the frequency time transformation as applied to a self
adjusting spectrum filter, together with breadboarding of
some critical circuits .
This last month has seen the completion and testing of
'the second compressive network, continuation of efforts to
complete the system, addition of amore linear sweep drive,
and positive results from the computer effort ?to analyze the
effect of time delay errors in the system.
The second network was completed using great care to
reduce all errors in alignment. I;eads were shortened to
rninirnize stray inductance. ~rThere lead length had to be
appreciable (up to 2 inches}, low inductance copper strips
were used to make connections. In tuning resonant circuits,
a frequency counter continuously monitored the input frequency
to insure a proper setting. The resultant network was then
tested using the carne method previously used to measure the
phase response of the first network; measuring the frequency
difference between successive nulls of the arithmetic difference
Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
between input and output. The first network response was
then measured again. The resultant time delay curves are
shown in graphs 1 and 2. Despite all the cares taken in
building 'the second network the magnitude of the time delay
errors of both networks is about the same. Also, the slopes
and linear ranges are remarkably equal.
Work has continued to complete the system. At present
just a few small chassis are needed in addition 'to the
present set-up.
The linear slope generator used 'to drive the swept
oscillators were rewired 'to provide a delayed inverse sweep
voltage. In addition the slope linearity was improved and the
fly'pack time was reduced to one usec.
In the computer department, an analytic solution has
been found which pre diets the difference between the o'oserved
output and a sin x~x waveshape due 'to errors in the systern
phase response. First, by minimizing mean square error, a
"best fit" linear time delay curve was found from the
experimental data. The phase error, ~ (Q , was then
approximated by the function,
Declassified in Part - Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
3-
Y is a dummy variable proportional to frequency. The
computer was then programmed to find the output with this
phase distortion. A comparison of the computed output 'to a
sin x~x is shown in graph 3. The width of the main lobe is
essentially the same, but the output is skewed and the largest
slidelobe is 10 db 'oelow the maximum output instead of 13 db
in the sin x~x. A photograph of the experimentally observed
output is included ~to compare with the computer results.
During the next month the system should. be completed
and tests on it begun. In addition some more effort in
amplitude shaping to reduce sidelobes is expected.
Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
 NO. 31S-C R. MILLIMETHR9. 190 DV 290 DIVISIONS. /:i3sa'~\ CODER BOOK COMPANY. INC., NORW OOD, M.4flflACN USETTt
Declassified in Part -Sanitized Copy Approved for Release 2012/02/21 :CIA-RDP78-03424A001200060016-7
o -o
5
.
~
_ i i
r g~'~
-'i
_ {
..r 1_
~
:I' ~
.#~ '
.
.i
_ .t~
'~,
~ -
~
1
{ _
t
tt
'
~:~.
`i
~
_
t
~
~
r
`~
i.
.it
.}.?
, i
. I
{,;-
~: r
1:..?1 ~
~+ ~
'
+ { :.
t;t
".1.+
rk~:;
_-
r
-:t:`:.
I ~i
!
~
r1-. ~~;i.
t..h =
'
-
t
1.
~
~ ._
~
;
~
,-+-
t
-
:
~
t
;
~
?
+ri
r'
~~
t_
~ t
1
I I
t
t
T
f
~
j
-
~.
T`
~ia~
r':
-
F
-
;
.
-
~
,y
I:<
i
'
L .1
`
'
.,,
';.
~
-
-
.Y
,. ~
~t.:
.
t
' ~` t..
~+~
~
I.
~
~
_+~:
"f
t
~+
~
- ~
Fr"-~
^+
'
?
:
.h
...
T
1~
r
r=~,j
t
!'
..
t
t.
S
4
:
L.
S
I
l-
t
t
C
St
...
:I.C'
~.L. +
i
'}
?
tcj
~,
1;-
t
t
~
+fi~
t,:
t
-
I
~
,
#L'II
.L
`' '41
-,
I.
'
.t
:-+
!1
-t
~"
`
.t
}
t
u'-
`i
I
.:
~'
^~.
-
~
-
T
y:~
..'.`
i
~ ~
i-+~
,
1
}
+:t
yet
.i.:
t r`
~
t
~ .i
.
r'
~
--~
~~
~~{
~
~'-~-
~._
`~
~..`
_#
..~
,
.~_
j
1I '
r
...
:i
?
,t. +
T'
_ +
~
_ k;~_
t,
~
-,.
~
~'.
~
~
7~..
-?
.'--~-;,.
+~
.~_
~~
t :.t:
-~
:t._:r
I
r
~
ar
I r
-1,-+
tT`
-
i.u
r~1
~
~
i
ri_
i.
.
~
`:'
:-.
'x *
I
~
'i
;t
L'
I
~,
i.,
,~
:#
I
-t
IIt
I
_
,~~t
+. L.
~ I
_ .tk
;a
..:~'-+
~
'
1
Lrt'.
r
t
.1
;:I'T
t
t.i
N
;
L; ~
`+
17'}.
t"
17
t
1
+
~
i
.
j
`'
.}
_"+
t.
+
~,ti
~
#+'
-
.:.r
_
'
:~
~~
-
,~
+~
:=
:
~i: ~
-
~~
~
.f
S
~
!;
~
{--
~::
Lr
I
I
m
.-.{
t
}-^
L
[,-i
:
+.
.,
,'t~
I
t~l.
I, ~
I:.
+:3~
..
-r
,~-
:
;
~'.J.
~
_ . ii
f
_
} R
..
r
_
r I
Iy
j
t'
:y +
.t_
1
~
.+.
'{'
'`
.
t ~:
~ ~
"-1~~"
il
}_
t `
7
,t` f.
~;
-
~. .{
, '~
-~:
_
I.i
'+
r
t.i.
t
~-.
.t.
7.
}~
"1
1
1
~~ ~
.
r;
Nr
t-:-;
ri
2Z
+
~'
i
.t
tt}
-
~rl
ItI
}Q-~
;}
~`;
`
t+:-
+
t
+}r $
nor lls
.
+ L 1'tr
-r`
+.
1
+
;
;,
t
~
rx
?~
i
1.*Ix
Y:
.+
. +-
r,
It
$?.
. ~t
.~;,
a
?t'
`.~
1
It
+
~+1^
r
.~
t
:_r~,
-
~L
.-?'
'~
t,
.'.:
+
r
..,
j
r +
it
.
'" t
~
:
:t
r t
,
+
,+-.
~,
itT
I
~,
:a
t
.t.
z#x
2+
H_.
1,
~:t
i
~
N
k{
, C
it
+
i
.}t
}
;,5`
1,
+
r
It
_
I't
r
It
}.
+
~
~
~*
x+.
C_
r
-,.
~
-
[_+-
~
~_
1
v
?r
+
_
t
~Lr
'{.-.
+
`trt
If
';
~
;
~ 't
r#
..?-I
!
~
F'?Y'i
+I
'.,'
:~.
a
~.
:z
.'.F.
r
"i
~"
}1!-F
t i!
'-.k~i
It
E
_I.
is
`';r+
-~'~{
'" r
F
it
t
7t
j-.
~
-t2
i
u:~
#
.'1
~
-
:`
{Z~'
r
~
'.,1+
hr-:
~
+'~?
i
:
1
~,...,
"t-:
~
.
.
,
.
,
.,;.
,,
.
-
~
:~
~
,.
_
.,.~
.
}
.
.
+
~
~
iz.
_
.+.
't
.-..
_
r
i ;
-
%+t
c
:~
`:.
~:
i
+:
I ~
'F.j
~}:r
_i
~
r
~.,
{4
{t
~
`
+~
-Lr.
.~h+`
-+~
~
"~
:-_.
'
'~"
..,~
~#
:
j
, ~ t
:'y
_
`.:-r
~+
I
:~*
l+.I
'(+
f
"+
t
i ~
,-*;
,
[
'
.
1`.
T ..,
~
"-}
,
I t t
t'
`
=#+i
~
,
'`
r++}
: 21
+y,
r ~
Lx
_
k'
tom'
7
~^
;:?`
f'
+
~+..
jt1
I.
+ -~
~I.
L.
.~
,.
_
-~''
~
'-?fC
`
r
'::t:
.
't
`
t
t L
I
#2-
_~
`
TM
'
'
~~#~
r
'
'
+ .
1?.
+-.
r~.r
.1L
r
h.
}..t.
k
I~
-:.
-t-
h
-+~
?-
..
..
i
.
?
a=tr
:
.
,
.
:.
.
I
I
I
~
`,
i
,
i
`
r
-.4
l
i
'~,
.. j
}
tI
-
-
.Y+
fi+
: