Station Readiness Tests
during Apollo 16

Tape track 2 – Notes by Bryan Sullivan



Explanatory Preamble

The recording commences just prior to the start of the up-link and down-link voice checks (referred to as air/ground tests). These tests occurred in the countdown to the AOS (Acquisition of Signal/Spacecraft) at the H-45 minute mark. This voice testing procedure verified that the MCC-H CAPCOM (Capsule Communicator) was able to talk to and hear the astronauts during the up-coming station’s tracking period.

Initial testing involved the reception of audible signals from MCC-H where the level (strength in decibels) and the frequency (tone in hertz) was measured.

There were two different signals, one representing a ‘mark’ and the other a ‘space’. These two signals triggered a unit (referred to as the Quindar key) which switched the in-coming and out-going voice circuits between the appropriate USB PA (transmitter) and the respective demodulator for each system’s designated spacecraft. Test counts were then sent by MCC-H with alternating switching tones representing the on and off functions of the press-to-talk switch on the CAPCOM’s microphone. These tones were always heard within the tracking system’s ground network but never heard by the astronauts who only heard the (CAPCOM’s) voice modulation from the station’s PA (transmitter).

Finally, test signals (down-link tones) are sent from the station’s demodulators to MCC-H where the HOUSTON COMTECH measured the levels and frequencies received. Air/ground voice checks were performed at H-45 and H-5 minutes for each nominated spacecraft in the station’s tracking schedule.

Tracking CADFISS testing was still in progress with the ‘wing’ site (HSKX [Tidbinbilla]) .

Listen to the audio of Part 2 of the tape – 10 min 04s – 1.2MB mp3 file.

(Opens in a new window.)


Personnel heard on this tape:

OPS2 Bryan Sullivan
COMM TECH Dave Ralph ?
GDS Bill Sheridan
COMMS Keith Hiscock
OPS1 Bernard Smith
SB1 Frank Campbell
SB2 Neil McVicar
COMPUTERS Don Loughead
DATA Bill Perrin

Start of Tape track # 2

Times in red are from the start of the audio file.

00:00. HOUSTON COMTECH checks if HSK is ready for the ‘H-45 interface test’. This testing is coordinated by OPS2 in conjunction with the local (HSK) COMMS Supervisor, HSK COMTECH (located at the SDDS) and HOUSTON COMTECH over NET1.

00:25. CADFISS TRACK advises a successful ‘wing’ site high speed tracking data transmission test and requests a switch to the ‘prime’ site.

00:44. HOUSTON COMTECH commences the air/ground testing with a ‘mark’ tone. All of the measuring is carried out by the COMMS Supervisor at the patching and testing panels in the Communications Centre.

01:58. HOUSTON COMTECH commences a series of alternating keys to test the Quindar’s switching function after which OPS2 reports the percentage of key switching.

02:17. HOUSTON COMTECH requests the system configured for tracking the CSM spacecraft to be ‘remoted’ (switched) onto NET1 for a keying and modulation test through the USB system.

02:47. After the HSK COMTECH (at the SDDS) is satisfied, OPS2 reports 100% keying and modulation.

02:52. HOUSTON COMTECH conducts identical tests for the LM system and the LCRU (Lunar Communications Relay Unit on-board the Lunar Rover Vehicle).

04:02. Finally HOUSTON COMTECH requests down-link tones from each system’s configuration – CSM, LM and LCRU which are each measured at MCC-H.

05:07. OPS2 talks with SB2 (USB Supervisor, Tidbinbilla) regarding an outstanding ‘red’ item on their station status report. HSK requires an ETO (expected time of operation) either verbally or by a status update ‘twix’. A twix or TWX [Teletype Writer eXchange] was a printed message sent via teletype over the NASCOM universal system for intrastation messaging. It was very similar to today’s email, only much slower.

06:07. CADFISS TRACK reports a success on the APP (Antenna Position Programmer) test where the antenna is driven over a predefined sector of the sky and tracking angles and rate measurements verify correct operation of the antenna servo drive mechanisms (referred to as a ‘slew’ test). CADFISS TRACK then requests the ‘wing’ site for a similar test.

06:25. OPS1 requests SB2 to prepare for a slew test.

06:59. OPS2 requests COMPUTERS for a LOS/ROS (loss of signal/return of signal) manual entry via the telemetry computer console which puts a file mark on the telemetry log tape.

07:06. CADFISS TRACK reports a success on all HSK CADFISS testing and releases the site.

07:19. Goldstone and Hawaii are now five minutes away from AOS (their moonrise time) as HOUSTON COMTECH conducts a final air/ground voice check.

08:01. TIC (Telemetry Instrumentation Coordinator, MCC-H) requests Hawaii to configure for a ‘CSM mode 3 dump’. This referred to a playback of the on-board recorder of all the astronauts’ conversations and telemetry data while the spacecraft was behind the Moon and consequently out of contact with MCC-H. This playback happened while the real time data was being received and processed.

08:22 = 81h 4m GET. APOLLO CONTROL makes another PR briefing where he indicates that the LM spacecraft is now in a scheduled elliptical orbit (descent orbit) which is important to achieve before the astronaut’s rest period. The CSM remains in a circular orbit and will appear from behind the moon just prior to the LM.

09:27. Both Goldstone (GDS) and Hawaii (HAW) acquire the CSM spacecraft signal and Goldstone establishes two-way lock and announces ‘GO for command, CSM’. [Bill Sheridan working on the M&O console at Goldstone announces they have AOS.]

Two-way lock meant that the GDS receiver, its PA (transmitter) and the spacecraft transponder frequencies were locked together and the station was automatically tracking (auto-track) the spacecraft. Since the GDS PA was radiating, the ‘GO for command’ enabled the RTC (Real Time Command) controller in MCC-H to send digital data in the form of discrete commands and blocks of ‘software’ to the spacecraft subsystems and to on-board computer respectively. The HAW station receivers were passively locked onto the stable transponder’s down-link signal, referred to as three-way lock.

09:43. OPS2 checks with the DATA supervisor regarding the ‘SM 6 bits’.

This was in reference to the telemetry data from the scientific experiments located in the service module (SM) of the CSM spacecraft.

09:51. TIC queries HSK regarding the absence of LM data.

Due to the HSK geographical displacement from Hawaii and the difference between the two spacecraft orbits, the HSK received signal strength from the LM was slightly too low for the decomutators to synchronise with the telemetry bit stream, hence no data transfer to the telemetry computer and hence no data was being transmitted to the MCC-H on the high speed lines.

End of audio tape part 2.


Back to Part 1.

Notes by Bryan Sullivan. Times and other notes in red by Colin Mackellar.