3) Test patterns (RETMA charts) are photographed to permit complete analysis of TV performance (resolution, definition, response, and distortion of pattern). TV video output is recorded on magnetic tape and by photographic recording of image received on a cathode ray tube.

2. TV Subsystem Checkout

This is a procedure identical to the TV portion of the System Test conducted with the TV Subsystem off the spacecraft.

3. Mission Tests

In these tests the spacecraft is operated in a simulated thermal vacuum environment through all flight events associated with launch, separation, midcourse, terminal maneuver, and the final approach TV operation. The tests consist of successful completion of two programmed 66-hour missions (actual test time exceeds 66 hours).

1)

Criteria for acceptance of the TV Subsystem is no failure that would preclude obtaining all scheduled pictures from all cameras.

TV is operated in both warmup and full power modes

With collimators installed, checkout of video performance is identical to a system test.

Precountdown Procedures

These are spacecraft systems checkouts conducted prior to launch countdown.

1) The spacecraft is mounted on a system test fixture for dummy runs at
JPL and at AMR.

2)

Prior to launch countdown the procedure is run at AMR with spacecraft on pad in launch configuration on the Atlas Agena.

3)

4)

TV Subsystem is checked by photographing a series of lights under the shroud. System performance is checked by image of the lights and by the reproduction of the reticles.

TV RF transmission through the high gain antenna is in a reduced power mode (i. e., the final power amplifier is not energized) to avoid accidental firing

of squibs or ordnance devices in spacecraft or the Atlas/Agena booster system by the high RF power.

2) TV Subsystem checkout is identical to that of the precountdown procedure.

After the TV Subsystem was integrated with the RA-6 bus, the following TV Subsystem checkouts were performed at JPL:

Type of Test

Table N-1. Chronology of RA-6 TV Subsystem Tests at AMR

B.

PERFORMANCE HISTORY SUBSTANTIATING A FLIGHT-READY TV

1. TV Subsystem Turn-On

At the time of the final System Test at AMR, the RA-6 TV Subsystem had logged approximately 160 hours. This represents at least 400 cycles of turn-on to warmup and switchover to video transmission (at either full or reduced power). Not one single failure to turn on or switchover was encountered. This series included the initial commanded turn-on and switchover following shipment of the spacecraft system from JPL to AMR. Further, the turn-on history includes periods between turn-on's to durations of longer than 12 days with no failures to turn on and switchover.

The final system test at the final ESA check, and the final countdown procedure, were conducted without a failure to turn on and switchover to video transmission.

Both the TV Subsystem and system test records indicate a consistent stability in calibration and alignment, with no history indicative of probably degradation in picture quality resulting from turn-on turn-off cycles or periods of shutdown.

3. TV Subsystem Failure Reports History

Both the PTM TV Subsystem and the RA-6 flight unit had low failure report histories. Aside from reports involving minor mechanical items, the reports are limited to:

a. Battery Failures (i. e., drop in voltage output)

The batteries employed in the TV Subsystem are rated for one recharge cycle. To minimize battery changing delays during testing, and to ascertain realistic available battery life, marginal testing is conducted until the battery output drops to an unacceptable level. Failure reports written when batteries failed indicated that all such failures occurred on the 3rd, 4th or 5th recharge cycle. No failures were encountered within the rated one recharge cycle (this condition prevailed during the considerably greater amount of PTM testing as well as with the flight unit).

The flight batteries used on RA-6 were installed at the start of the final system test at AMR. At launch these batteries were at an early point in their rated life span.

b. Shutter Springs

One failure of a shutter detent spring was encountered in the RA-6 flight unit. At launch the camera shutters had been operated approximately 1400 cycles on the two wide angle cameras and 8400 cycles on the four narrow angle cameras.

c. RF Dropout

Two reports during early RA-6 flight unit checkouts involved RF dropout (i. e., transient reduction in RF output below video transmission level with recovery to normal level). Each event was a single transient of less than 1 second duration. This performance, if encountered in flight, would result in only a negligible degradation in picture quality or loss in number of planned TV pictures.

This condition was studied and a redesigned four-port (change from coaxial to printed circuit design to avoid cavities and voids) was subjected to requalification on the PTM, TA, and FA testing without indication of the phenomena. This testing included operation at 90 watt power levels through critical pressure environments without indication of variation in RF output.

d. Inadvertent TV Turn-On

Checkout indicated
This action is not

During ESA checkouts at AMR, two inadvertent TV turn-ons were encountered when the TV battery plug was inserted to switch from external to internal power. that a transient generated by the action triggered the TV turn-on circuits. associated with any flight sequence operation and is therefore restricted to a ground check procedure.

The last full power check on the RA-6 TV Subsystem was made 12 days prior to launch; the last reduced power check was made four days prior to launch. The only element of the TV Subsystem that is in operation in full power mode, and not in operation in reduced power mode, is the final power amplifier. All other TV components are functioning in the reduced power mode as in the full power mode.

Full power and, therefore, activation of the final power amplifier is not applied during checks on the pad to avoid exposing the ordnance items of the spacecraft and the Atlas/Agena to the full RF power of 60 watts that could trigger the squib elements.

This constraint upon TV Subsystem checkout is not considered significant in terms of reducing the probability of a successful turn-on in flight. The only item that is not checked in the reduced power mode is the final power amplifier. This unit did not have a single failure at turn-on or during operation throughout PTM and flight unit checkouts. The typical failure pattern of this unit is a long period (a span of many hours in relation to operating time of the next mission cycle) of gradual decay in output, which would have been detected during checkout monitoring to permit replacement prior to or during final system test.