Apollo radio

"Wpai" wrote in message
...
Space communications has a few challenges -- especially a lunar mission:
Doppler effect (spacecraft), multiple communication points (CSM, LM,
S-IVB,
landing site) with small antennas that are largely omnidirectional
(except
S-band array on SM and landing site dish); power budget

Ths dish was the steerable high gain antenna they used during the lunar
landing?
If it was, how was it steered? By hand or automatic?
Why, on Apollo 11, was the LM ordered to yaw 10 degrees, if the dish
itself
was steerable?

In which way the CM was involved in the communications between LM and
earth?


I believe Apollo 11 transcripts specifically cover Buzz Aldrin's switching
through different antennas
to improve LM telemetry and communications with Houston (via the large radio
dishes on Earth).

During this communications problem, Mike Collins in the CM had to relay
commands he heard from Houston
to the LM crew.

http://www.iee.org/OnComms/pn/Histor...Apollo_CSM.pdf
The communications system devised for Apollo was more complex than any
previous
spacecraft system simply because of logistics. The CM had not only to
communicate
with the Earth, but also with the LM in lunar orbit and on the surface. The
system
supplied by Collins Radio Co (merged into Rockwell Collins in 1973) was
required to provide voice, television and data links, most importantly for
telemetry,
tracking and command data.
In addition to an omnidirectional antenna, which allowed a link with Earth
to be
maintained irrespective of the spacecraft’s orientation, the SM carried a
steerable S-band
(2 GHz - 4 GHz) antenna comprising four 80cm-diameter parabolic dishes on a
deployable boom.
This high gain antenna could be steered manually or automatically
to track the LM or maintain the all-important link with Earth.

w9gb

For the Apollo radios ... I seem to remember that Motorola and Collins
were
2 of the major mfg.
Going to have to dig through old files for details

gb

In my search for details I found this:
http://www.astronautix.com/craft/csmtions.htm

HE