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FINAL• REPORT 

BIT MISSION 7057 

26 May 1965 

SAFSS_ 

-ME11647._ 

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This Document Cdnsists of --41-/'?...Pages. 

Copy No7 of Copies, Series EDI, 
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FINAL REPORT 

BIT MISSION 7057 • 

1. `t* MISSION SUMMARY. 

1.1 Program Objectives. 

The objective of the BIT program is to determine if and when 

the radar system associated with the signal acquires and tracks 

the Agena vehicle. The BIT system, designed to fulfill this objective, 

covers the frequency range from 153 to 163 Mc and accepts only those 

signals which have characteristics similar to On those signals 

which qualify, the system will measure frequency, PRF, and signal 

amplitude along with the time of intercept to enable an analyst to 

identify the signal characteristics and to estimate a geographical 

area within which the emitter is located. 

1.2 Mission Highlights. 

On orbit 8 of this mission the BIT system intercepted an unidentified 

signal as the vehicle passed approximately 420 nautical miles due west 

of Sary Shagan. Because of the location of the vehicle during the intercept 

and the power level of the signal, it is suspected that the emitter may 

be .the same as the emitter; however, the signal cannot be identified 

as because of the PRF. The signal, which was intercepted from 

0902:49Z to 0904:46Z on 26 March, had sufficient signal strength to 

permit the detection of the Agena vehicle by the emitter. This detection 

and possible tracking event occurred only during an 18-second period 

when the signal strength reached a level of -22 to -13 dbm at the vehicle 

and the PRF was steady at an average rate of 85 pps. 

No other signals of interest were noted during this mission 

which was prematurely terminated by a commutator failure sometime 

after orbit 33. The BIT system was functioning properly throughout 

the useful life of the mission which started with the vehicle launch at 

approximately 2100Z on 25 March and ended sometime after 2200Z 

on 27 March 1965. 

1.3 1.)„.Flight Summary. 

Vehicle Number 1612 

Launch Time 2118Z 

Launch Date 25 March 1965 

Inclination 96 degrees 

Apogee 154 nautical miles 

Perigee 100 nautical miles 

Period 89 minutes SPECIAL HANDLING 
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2. NI MISSION COVERAGE. 

2.1 1164.. Operational Coverage. 

The BIT system was programmed on during each of the first 

33 orbits of the useful mission life while the vehicle was over the northern 

hemisphere with an emphasis on the coverage over Europe, the USSR, 

and Asia. On 4 of the orbits the unit was programmed on throughout 

the period while the vehicle was over the southern hemisphere. Data 

were received from all of the orbits which were programmed for operation.. 

2. 2 'Kik._ System Coverage. 

The BIT system, shown in Figure 1, monitors the 155 to 162 Mc 

frequency range with a receiver sensitivity of -54 dbm. With the 

inclusion of the effects of the antenna pattern with different polarizations 

and aspect angles, the over-all detection sensitivity of the system ranges 

from -57 dbm to -45 dbm. Signals intercepted by the receiver are checked 

by a pulse width qualifier to determine if the pulse width is greater 

than 18 microseconds. The pulses which qualify are counted in a total 

pulse counter, PRC, over the commutator read-in interval of 400 

milliseconds and checked to determine if the PRF falls within the 94 

to 101 pps acceptance band or harmonics of this range. The system 

measures pulse amplitude and RF frequency on those pulses which 

satisfy the PRF criterion. If a signal has a power level at the receiver 

in excess of -30 dbm, its amplitude will be measured in the PLD-A 

channel regardless of PRF or pulse width. The RF frequency of the 

high amplitude pulses will not be read unless the signal also satisfies 

the pulse width and PRF criteria. 

3. 1.14 MISSION RESULTS. 

3.1 PRF Qualified Intercepts. 

3. 2 1.54. Non Qualified Intercepts. 

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3. 2 *IS). - Continued. 

--SEGQ7 

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ANTENNA GAIN 6:10 

RELAT IVE TOISOTROPIC 
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3. 2 N4 -- Continued. 

4. hca.) SYSTEM PERFORMANCE. 

4. 1 *Sb.L System Specifications. 

A summary of the system specifications for the BIT system used 

on this mission is given below. A block diagram of the system is shown 

in Figure 1. 

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4. 1 -- Continued. 

Minimum Detectable Signal - 54 dbm PLD-B 

- 30 dbm PLD-A 

Minimum Acceptable Pulse Width 18 Microseconds 

PRF Qualifier Acceptance Range 94-101 pps 

187-203 pps (2nd Harmonic) 

RF Passband 

-51 dbm 155.7 to 161. 6 Mc 

-25 dbm 148.3 to 174. 5,Mc 

4. 2 14S11% System Operation. 

The BIT system functioned normally throughout the useful 

mission life which ended after orbit 33 when the commutator failed. 

From the commutator wavetrain data it is apparent that the commutator 

started when the system was turned on for read in on orbit 34 but it 

jammed and stopped on one of the synch channels after one commutator 

revolution. Thus, for the remainder of the scheduled mission, the 

output of the system remained at 5. 3 volts on both stored time (channel F 

VCO) and real time (channel 14 VCO) read outs. , 

The cause of these failures in the electromechanical commutator's 

has been identified to be poor design in the motor brush assembly and 

several corrective measures have been taken by commutator manufacturers 

to prevent similar failures in the new models. This, however, will 

not solve the problem with the remaining BIT commutators which were 

built prior to the correction of this problem. The only effective solution 

to the problem of the BIT commutators is the replacement of the existing 

units with new commutators which utilize recently developed roller 

bearing brush assemblies. These devices have recently been extensively 

tested by Lockheed and it was found that they are highly reliable. Since, 

as of this date, there are only three BIT units remaining, the flight 

schedule for the units would be interrupted if the commutators were to 

be replaced in the three systems. As a partial solution to the problem, 

the commutators have been rewired in the remaining BIT systems so 

that they will operate continuously rather than being programmed on and 

off with the system. It is hoped that this will improve the operational 

reliability of the commutators. 

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