NRO APPROVED FOR RELEASE 

1 AUGUST 2015- 

e-R.ELL:.§PECIAL HANDLINL 

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OPPORKNC.),CKTTY S TS Tal 

TECHNICAL DESCRIPTION 

- PRELIMINARY - 

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--'-'ttrPECIAL 'A 4.A.ING 
NRO APPROVED FOR RELEASE 

1 AUGU-ST 2015 

AW007.':7 

The Opporknock i ty system scans the £6 to 72 MC band in 256 steps, takinF 

two seconds, stopping for 0.5 seconds on all carriers to the band that satisfy 

the PRIMARY HOLD conditions, i.e. only one tone present in at least one of the 

two TT channels. During the 0.5 second hold, L HOLD, the signal is tested by 

the secondary recognition for tone switching in either or both channels. If 

tone switching is present during the first "i(>0 msec of the L hold the receiver 

remains locked for two seconds (H HOLD). After two seconds the receiver is 

allowed to scan. During the first 4o msee after the hold. the receiver is 

force scanned to prevent AFC action from causing another hold on the same 

signal. If the signal should fade or drop out after the system has gone into 

a two second (M) hold the system wilj remain locked and not sweep for three 

seconds (N HOLD). After three seconds the system will be force scanned and 

allowed to continue the sweep. The mode of operation Just described is 

designated MODE A. 

In the MODE B operation the receiver stops for 0.5 seconds on any signal 

in the band that satisfies the PRIMARY HOLD conditions. During the L HOLD the 

signal is tested by the secondary recognition for tone switching as described 

for Mode A. If tone switching is present the system remains locked as long as 

the signal is present. When the signal fades or drops out the receiver will 

remain locked for an addition/11 three seconds (N HOLD). If the signal returns 

within the three second hold period the receiver remains locked. However, if 

the signal does not return within the three second hold period the receiver 

will be force scanned and allowed to sweep. 

T.s;r•-•!' 
NRO APPROVED FOR RELEASE 

1 AUGUST 2015 

In the MOT:', C operation t.ru: secondc on all aarriers 

in the r:ana that; niti the Prim •crY I ons hur the the 

i na1 is tested by the Secondary ieop,niton for tone switching or described -

for Mo,.-:e A. If tone nwitohinc I arerent the receiver will remain locked as 

lon;!: as the siRnal is present. Wh-n the fades or drops out the receiver 

will remain locked for an additional ;() seconds. The receiver will remain 

locked if the sirnal returns within an 1-,r:cond hold per!Lod. If the signal 

does not return within the 60 seconi Sold period the receiver is force 

scanned and allowed to sweep. 

The receiver system contains an rf calibrator that operates six seconds 

out of every minute thus giving 5h seconds of video data and six seconds of 

calibration data. The calibration signal is injected into the front end of 

the receiver. During this time the signal from the antenna is attenuated. 

The frequency of the calibration signal is 67.4 mc modulated by a continuous 

C tone. 

Durlag the MODE C operation the calibration signal is disabled. --• 

Mode A, B or C operation is selected from the ground by real time command. 

The receiver has a sensitivity of one microvolt or -107 dbm. 

The receiver system contains a solid state commutator. 

The commutator has eight segments which are designated as follows: 

Segment Designation Normal Outnut @ 70°F 

Ground Ground Ref. Zero Volts 

2 Reference Voltage 1.6 Volts 

3 +18 V Monitor 2.7 Volts 

4 +15 V Monitor 3.6 Volts 

5 Temperature Sensor 1.42 Volts 

"SteRELSPECIAL HANZLING 
NRO APPROVED FOR RELEASE 

1 AUGUST 2015 

6 or L Hold No Hold - Zero Volts 

With Hold 1.5 Volts 

7 14 Hold No Hold Zero Volts 

With Hold - 3.1 Volts 

Peceiver Sweep 2.0 to 4-0 volts 

The commutator has a frame rate of six framen per second. The resulting 

output; 4b samples/second, drives a channel 12 WOO. The VCO output is 

recorded on a tape recorder. 

During the read-in mode. of the system operation the signal is processed 

by the receiver (IRSC designation - 077/: D) OTEX D being previously selected 

to be in MODE A, B, 01: C. The video output and the channel. 12 WOO output are 

recorded on the six minute 1:1tape recorder. 

In the read-out mode of operation a 100 K Bit test pattern generator 

(designated OTi C) is turned on when the transmitters are turned on. The 64 

bit repetitive pattern is transmitted until, the recorder and delta modulator - 

signal modifier (designated OTEX F.) are turned on whereupon the video from the 

recorder is fed into OTEX E to be modified and then transmitted on LINK III. 

The other track of the recorder which has the channel. 12 VCO recorded on it is 

fed into the modulation buss of LINK II as is a 100 KC reference tone from 

the signal modifier ()TEX E. After six minutes the tape recorder is played out 

and the output of OTEX E is disabled. At this time the output of OTEX C is put 

on LINK III and this data will be transmitted until the transmitters are turned 

off. 
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NRO APPROVED FOR RELEASE 

1 AUGUST 2015 

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