[amsat-bb] Re: L band

Bill Ress bill at hsmicrowave.com
Sun Sep 10 23:47:38 PDT 2006

Hi John,

I have just re-read the Eaglepedia report of the San Diego meeting.

I must admit I continue to be shaken by Tom Clark's early statement about
his views on the L-Band situation and then with the table called "Band
Usage" which states L-Band usage (for digital) "Discarded due to possible
L-band loss". I realize that this was referring to DIGITAL band allocations
and that later a table called "preliminary power budget" includes 3 watts
for a L-Band ANALOG receiver but I have been concerned that this position
about digital L-Band is based on the unsubstantiated and unproven notion
about the "government(s)" taking us off the air there.

John, I think engineering decisions should be based, as much as possible, on
real facts and data - not a notion about the future.

Now another question. Why can't the L-band analog receiver (if it remains)
be used for digital modulation (i.e. digital backup). Down to an IF
frequency or modulation detection frequency it shouldn't care if the
modulation is analog or digital. Have I  missed something?

Regards and thanks for your patience and time responding to my posts.

Regards...Bill - N6GHz

-----Original Message-----
From: John B. Stephensen [mailto:kd6ozh at comcast.net]
Sent: Sunday, September 10, 2006 10:59 PM
To: i8cvs; Bill Ress; jules at g0nzo.co.uk; AMSAT-BB
Subject: L band

One thing may not be clear to all AMSAT members. There is still an L-band
receiver in the Eagle requirements document for the analog transponder. The
San Diego meeting recommendation was to move the digital transponder uplink
from C to S. So far, no decision has been made to eliminate the L-band
analog uplink.

The analog transponder has a U uplink so if L becomes inaccessible, it still
works. The digital transponder has no secondary receiver so its uplink
frequency is more critical.



> > I would like the AMSAT decision makers to detail the reasoning for
> > dropping  the L-Band Uplink like a hot potato besides the "Galileo"
> > excuse. As yet, I can't find it in Eagelpedia.
> > In view of Peter Blair's (G3LTF) paper (PLEAS SEE JULES LINK BELOW) I
> > cannot see any rational for dismissing Eagle use of the L-Band satellite
> > Uplink allocation.  I don't thing using the statement that "we will lose
> > our  L-Band allocation" is indicative of the much appreciated "science"
> > the team is bringing to the Eagle design process.

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