In preparation for this test, several tapes were generated. In order to provide a calibrated test tape for this analysis, the tapes prepared at DSIF 12 on 3 Feburary were used. These tapes were made by pointing the antenna at the Moon and injecting a JPL transponder signal of -118 dbm into the maser input, thus simulating the known mission signals. Calibrated video signals were then injected into the maser from the RCA OSE at 10 db increments from -120 dbm to -170 dbm. This was then followed by emergency mode signals at the same signal levels.

On 7 February, a second tape was dubbed directly from the FR-800 rotary head predetection recorder through the RCA receiver and onto FR-1400 longitudinal tape. The tape generated from the FR-800 covered the entire mission from warmup minus six minutes to impact plus one minute, whereas the RCA mission tapes had, by prior plan, recorded the period from warmup plus 4 minutes to impact plus one minute.

On 8 February, a total of six separate tests were performed:

1)

2)

3)

4)

The test tape was played through the Venus Site equipment with the sync pulse
centered in the spectrum. The reason for this is that regardless of the nature
of the video signal, the sync pulse is stationary in frequency. The results of
this test were that a carrier of -150 dbm was very strong and a carrier of
-160 dbm is marginal, marginal meaning a 5 Sigma deviation from norm.
A mission dub tape from RCA Receiver 1A, Tape Machine #2, Track 2 was
then played through the Venus Site equipment. This represented the best
receiver tape combination. The center frequency for this scan was 376.2
kilocycles on the mission tape. A spurious receiver signal was found at a
level of approximately -140 dbm. This signal was confirmed to be
spurious by virtue of the fact that it persisted after impact. Precise
time was known on the tape since the NASA time code was recorded at the
time data was taken and in all playbacks of Tape A, the time code translator
was utilized. No other signal was found. Measurements made on a Block III
spacecraft point out that if no high voltage was applied to the output tubes,
stray leakage should have been -160 dbm to -170 dbm. Anticipated normal
signal strength was -97 dbm.

Next, the emergency mode test tape was used to determine system threshold.
The results were that a signal of -160 dbm averaged for only 38 seconds was
strong, while a 4 minute average yielded a 5 Sigma deviation at -170 dbm or
enough to be seen, if present, for the duration of the RA-6 emergency mode.
A run was then made of the mission data and again a spurious signal was
found which persisted after impact. No emergency mode signal was found.

32-445 O-64-28

5)

6)

Then, a frequency search for emergency mode was instituted with 33 1/3
kilocycle bandwidths centered on 475 kc, 500 kc, and 525 kc. The only signals
found were the persistent spurious receiver signals. Absolutely no emergency
mode was found.

The last run was made on the tape dubbed from the FR-800. It is known that
in normal warmup, the first 30 seconds, while the tube filaments are warming
up, yields an input to the maser of -140 dbm ±5 dbm. This level would
literally saturate the Venus Site equipment. Two one-minute runs were made
with center frequencies of 325 kc, and 350 kc. No signal was found even
though a one-minute sample should give us a 5 Sigma dispersion for a signal
of 156 dbm.

In the tests run at Venus Site, the maximum system bandwidth of 33 1/3 kilocycles was used, which if far short of the 260 kilocycle peak to peak signal swing or of the 800 kilocycle predetection bandwidth. However, the advice of the RCA cognizant engineer on the choice of search frequencies was used, thereby providing good prior knowledge of spacecraft behavior. Also, the broad spectral behavior of a wide band frequency modulated signal should have produced some signal within the passband had the signal been at a reasonable level such as 140 dbm.

One further point to be borne in mind is that noise spectral densities were subtracted where possible. On the FR-800 tape dub, a rather complete cancellation of noise spectral density was observed during the first minute of Channel F warmup. Had any normal warmup signals been present, or had incoherent video modulation been present, it is extremely unlikely that such complete cancellation would have occurred.

E.

CONCLUSIONS IN SEARCH OF MAGNETIC TAPES FOR RA-6 SIGNAL

It may be stated with confidence that:

1) No in band incoherent (noise modulation) transmission exists at an input power level to the maser of -120 dbm or higher.

2)

No in band video modulation exists at a level of -150 dbm or higher.

3)

No in band emergency mode modulation exists at a level of -160 dbm or higher.

Our failure to find any signal at these levels is a positive indication that the transmitter was not in reduced power. All evidence points to the conclusion that no L-band signal was present in the television transmitters.

F.

RA-6 MALFUNCTION INVESTIGATION PTM TEST NO. 2 SUMMARY

1. Purpose of Test

The purpose of this test was to determine whether or not a short or an open circuit at

J3 (the RF input to Case 2 from the TV) would cause a measurable effect on:

1) The signal strength of the 960 Mc signal received from the spacecraft radio.

2)

The telemetry indication of the spacecraft radio power output (Addresses
56 and 52).

The high gain antenna output of the spacecraft radio was hardline connected to the radio OSE. With the spacecraft radio transmitter operating in the high power mode, the signal strength was measured at the radio OSE and the telemetry indications were monitored at the Data Monitoring System for the following conditions:

1)

The TV (not energized) RF output cable connected to J3. (Initial reference) 2) The TV (not energized) RF output cable disconnected at J3.

4)

The TV (not energized) RF output cable reconnected to J3. (Reverification of reference)

1)

A 0.7 db decrease in received signal strength relative to initial reference was observed with J3 open.

2)

3)

A 0.9 db decrease in received signal strength relative to the initial reference was observed with J3 shorted.

No change in telemetry indications (one cycle resolution) was observed.

In conclusion it may be stated that either a short or open circuit at J3 would cause a change of slightly less than 1 db in the received bus signal level.

G.

SEARCH FOR RCA RF SIGNALS FROM TV SUBSYSTEM DURING BOOST PHASE

The search for RF radiation from the payload was broken into two parts. First, it was necessary to determine if DSIF 71 at AMR was capable of and, in fact, did see TV signals from the payload during the boost phase. The second part was to determine if any AMR

receiving stations monitored the spectrum in the vicinity of the RCA signals and if they saw any signals. DSIF 71 reports that no signals other than those emanating from the JPL transponder were observed during the 478 second tracking period. The transponder signal was monitored on a Panalyzer with a sweep width probably adjusted so that only the RCA Channel P could have been seen had it been on. The operators did monitor the Panalyzer when the RCA Channel 8 was reported on and at various times until loss of signal. They report that no TV signal was seen. The path loss of the RCA signal while under the shroud is not known; however, using estimates, it would probably have been possible to see the RCA signal on the DSIF 71 Panalyzer had the P transmitter been in full power. It is also probable that signals could not have been seen had the P transmitter been in warmup. The F transmitter signal could not have been seen since the Panalyzer was probably not set for this observation.

Reports from the Cape stations about observation of signals other than JPL signals are all negative with one exception. A telemetry ship, the Twin Falls Victory, reported seeing one carrier about 150 kc below the JPL frequency. This ship was stationed north of Ascension Island. The time of this observation is not known, nor is a level of confidence on this observation known. The spacing of 150 kc below the JPL frequency is not a normal frequency for RCA video transmission. Investigation revealed that this signal was spurious and did not indicate premature turn-on. It is possible that the spurious signal emanated from a receiver or spectrum analyzer or, possibly, that it was another signal present on the range.

1. Analysis of JPL Transmissions

From tests on the PTM it was determined that the JPL RF power output on the high gain circuit is affected by a signal level change of slightly less than 1 db by having an open or short circuit at the input to the directional coupler that mixes the RCA and JPL RF signals. Based upon a theory that an open or short may have occurred during the predicted turn-on of the RCA system, the Goldstone AGC records were examined to see if an approximate 1 db change in received signal level occurred at times when the RCA high power was predicted to come on, or at times when the emergency telemetry shoud have come on and gone off. Changes in signal level of this magnitude did not occur. It would have been possible to see a change of at least 0. 5 db during periods when the spacecraft was transmitting via high gain antenna and the signal level is relatively stable. During the boost phase, midcourse maneuver and other times when the low gain antenna is in use, the signal dynamics would make it impossible to observe a change of this magnitude in spacecraft transmitted power. However, the AGC records of the entire flight were scanned to look for this occurrence with negative results.

Measurements were made on the PTM under the shroud to determine if the JPL RF power monitor on the high gain antenna circuit is sensitive to the full RCA RF power. A