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Apollo Lunar Surface Communications Requirements



 
 
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  #1  
Old April 14th 12, 12:14 PM posted to sci.space.history
Alan Erskine[_3_]
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Default Apollo Lunar Surface Communications Requirements

Does anyone know how many communications circuits the large deployable
parabolic antenna could manage? There were voice, telemetry and video
circuits, but how many of each?
  #2  
Old April 16th 12, 11:20 PM posted to sci.space.history
Brad Guth[_3_]
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Posts: 15,175
Default Apollo Lunar Surface Communications Requirements

On Apr 14, 4:14*am, Alan Erskine wrote:
Does anyone know how many communications circuits the large deployable
parabolic antenna could manage? *There were voice, telemetry and video
circuits, but how many of each?


According to SETI, all sorts of communications (regardless of
frequency) can efficiently go to/from Earth, especially to/from that
extremely nearby moon, so I'd imagine those fancy NASA/Apollo
microwave antennas could manage as much bandwidth as anything we could
muster at that time.

Of course nowadays a compact, light weight and very energy efficient
laser communications beam would be just the ticket, with a focus of
roughly 2 km diameter if that were necessary. Otherwise a wider laser
beam communicator of something like a hand held cellphone or satellite-
phone would be more than sufficient for delivering an extremely wide
bandwidth and terrific data throughput.

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  #3  
Old April 23rd 12, 09:41 PM posted to sci.space.history
Brad Guth[_3_]
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Default Apollo Lunar Surface Communications Requirements

On Apr 14, 4:14*am, Alan Erskine wrote:
Does anyone know how many communications circuits the large deployable
parabolic antenna could manage? *There were voice, telemetry and video
circuits, but how many of each?


According to SETI, all sorts of communications (regardless of
frequency) can efficiently go to/from Earth, especially to/from that
extremely nearby moon, so I'd imagine those fancy NASA/Apollo
microwave antennas could manage as much bandwidth as anything we could
muster at that time, with very little loss of signal considering the
to/from path being perfectly clear.

Actually, the vast majority or terrestrial RF/EMF doesn't get outside
of our atmosphere, or at least not much past LEO unless it's of
microwaves and being directed or focused sufficiently, of which most
terrestrial microwaves are not.

Of course nowadays a compact, light weight and very energy efficient
laser communication beam would be just the ticket, with a focus of
roughly 2 km diameter at 384,000 km if that distance were necessary.
Otherwise a little wider laser beam communicator of something like a
hand held cellphone or satellite-phone configuration would be more
than sufficient for delivering an extremely wide bandwidth and
terrific data throughput once the extremely narrow channel is
established.

However, a tightly focused laser cannon method deployed in LEO could
get that intended target area down to a couple meters diameter for
that same 384,000 km distance. Now that's efficient communications.

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  #4  
Old May 2nd 12, 04:16 AM posted to sci.space.history
Alan Erskine[_3_]
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Default Apollo Lunar Surface Communications Requirements

On 29/04/2012 10:46 AM, Obviousman wrote:
On 14/04/2012 21:14, Alan Erskine wrote:
Does anyone know how many communications circuits the large deployable
parabolic antenna could manage? There were voice, telemetry and video
circuits, but how many of each?


The S-Band carried:

Voice
BioMed Data
EMU
PCM Telemetry
Emergency Keying
TV

Reading through the technical notes, it seemed there were radios
(TX/RX1, TX/RX2) and they operated on 2282.5 MHz for transmission, and
2101.8 MHz for reception.

Looks like there were five circuits:

Primary TX
Primary RX
Voice Backup
Emergency Key
TV (FM)

I've attached some detail which may help.


Good man; thank you! That goes a long way to answering my questions and
helps me with my own concept. Thank you very much. Where did you find
this?
  #5  
Old May 2nd 12, 07:01 AM posted to sci.space.history
Obviousman
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Posts: 67
Default Apollo Lunar Surface Communications Requirements

From NASA Technical Note TN D-6974 Apollo Experience Report - Lunar
Module Communication System available for download free from the NASA
Technical Reports Server (NTRS):

http://ntrs.nasa.gov/search.jsp

Direct download of that file:

http://hdl.handle.net/2060/19720023255


On 2/05/2012 13:16, Alan Erskine wrote:
On 29/04/2012 10:46 AM, Obviousman wrote:
On 14/04/2012 21:14, Alan Erskine wrote:
Does anyone know how many communications circuits the large deployable
parabolic antenna could manage? There were voice, telemetry and video
circuits, but how many of each?


The S-Band carried:

Voice
BioMed Data
EMU
PCM Telemetry
Emergency Keying
TV

Reading through the technical notes, it seemed there were radios
(TX/RX1, TX/RX2) and they operated on 2282.5 MHz for transmission, and
2101.8 MHz for reception.

Looks like there were five circuits:

Primary TX
Primary RX
Voice Backup
Emergency Key
TV (FM)

I've attached some detail which may help.


Good man; thank you! That goes a long way to answering my questions and
helps me with my own concept. Thank you very much. Where did you find this?


  #6  
Old May 2nd 12, 01:09 PM posted to sci.space.history
Alan Erskine[_3_]
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Posts: 1,026
Default Apollo Lunar Surface Communications Requirements

On 2/05/2012 4:01 PM, Obviousman wrote:
From NASA Technical Note TN D-6974 Apollo Experience Report - Lunar
Module Communication System available for download free from the NASA
Technical Reports Server (NTRS):

http://ntrs.nasa.gov/search.jsp

Direct download of that file:

http://hdl.handle.net/2060/19720023255


Your nickname holds true - I already had the report. I'm such a dill. ;-]

Thanks for that.

  #7  
Old May 8th 12, 12:34 AM posted to sci.space.history
David Lesher
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Posts: 198
Default Apollo Lunar Surface Communications Requirements

Obviousman writes:

From NASA Technical Note TN D-6974 Apollo Experience Report - Lunar
Module Communication System available for download free from the NASA
Technical Reports Server (NTRS):


I still don't know why the VHF comm systems were AM, not FM/PM.
Why would they have chosen to have to have modulators & such
rather than use alternatives?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
  #8  
Old May 9th 12, 05:15 PM posted to sci.space.history
Philip Lantz[_2_]
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Posts: 10
Default Apollo Lunar Surface Communications Requirements

David Lesher wrote:
I still don't know why the VHF comm systems were AM, not FM/PM.
Why would they have chosen to have to have modulators & such
rather than use alternatives?


Isn't AM dead simple compared to FM? Less complexity means less to go
wrong, and probably less weight, too.
  #9  
Old May 11th 12, 04:59 AM posted to sci.space.history
David Lesher
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Posts: 198
Default Apollo Lunar Surface Communications Requirements

Philip Lantz writes:

I still don't know why the VHF comm systems were AM, not FM/PM.
Why would they have chosen to have to have modulators & such
rather than use alternatives?


Isn't AM dead simple compared to FM? Less complexity means less to go
wrong, and probably less weight, too.


It's the other way around. FM/PM modulators are super simple;
amplifer stages after that can be Class C, not A or AB1. M needs
modulation applied the output stage, more power needed to do
that.



--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
 




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