Lou:
Makes sense; please provide some more detail.   A drawing and loss figures would be useful.

Thanks & 73,
Jim
wb4gcs@amsat.org


Louis McFadin wrote:
It seems to me that a more reliable design would avoid relays to  
switch between the Gain and the Omni antennas. It would be better to  
use directional couplers that feed the signals from both antennas to  
the receivers.
Relays have to be commanded and can fail. A coupler is doing it's  
thing all the time.

On Sep 23, 2006, at 1:47 PM, John B. Stephensen wrote:

  
I think that the L band receiver could be used for multiple  
purposes --  command, linear transponder uplink and digital  
transponder uplink. See the attached diagram.

73,

John
KD6OZH

----- Original Message ----- From: "Rick Hambly (W2GPS)"  
<w2gps@cnssys.com>
To: "'John B. Stephensen'" <kd6ozh@comcast.net>
Cc: "'EAGLE'" <eagle@amsat.org>
Sent: Saturday, September 23, 2006 16:15 UTC
Subject: RE: [eagle] Re: IF switching


    
John,

We should have omni antennas for perigee commanding. That tends to  
work when
all else fails.

Rick
W2GPS
AMSAT LM2232


-----Original Message-----
From: eagle-bounces@amsat.org [mailto:eagle-bounces@amsat.org] On  
Behalf Of
John B. Stephensen
Sent: Saturday, September 23, 2006 12:10 PM
To: Robert McGwier
Cc: 'EAGLE'
Subject: [eagle] Re: IF switching

Bob:

In Mirek's design there is an L-band receiver PCB and a command  
receiver or
command detector PCB mounted in one module. The two connect via  
the 10.7 MHz

IF. Command detectors could be connected to both the U and L  
receivers.

Are you suggesting one L receiver connected to an omni antenna and  
used only

for the command link and a second L receiver connected to a gain  
antenna and

only used for the transponders? A smaller solution would be one L  
receiver
with an antenna relay.

73,

John
KD6OZH

----- Original Message ----- From: "Robert McGwier"  
<rwmcgwier@comcast.net>
To: "Robert McGwier" <rwmcgwier@comcast.net>
Cc: "'EAGLE'" <eagle@amsat.org>
Sent: Saturday, September 23, 2006 04:25 UTC
Subject: [eagle] Re: IF switching


      
Robert McGwier wrote:
        
Robert McGwier wrote:

          
The downlinks in Lyle's SDX block diagram are two-fold.  S and  
V.  The
only change I would make for Eagle is to make both of them  
HELAPS. This
might prevent both of them being used simultaneously as HELAPS  
but it
might not.  We might choose to do a "delay only" version of the  
HELAPS
for the second transmitter.

I would like to suggest that we use Mirek's command receiver to  
feed the
exact same command receive technology to be used for P3E and  
that is the
SDR/FIQ channel on the IHU-3.   The less work we have to  
repeat, the
better.  I believe we should have stand alone command receivers
independent of the transponder antennas.  I would like to hear  
from John


            
Errrrr.    Uhhhh.  We might need antennas.  I meant independent  
of the
transponder receiver antennas.

          
I am definitely going to bed now.   Independent of the transponder
RECEIVERS.  That only took 3 times to get right.

        
and Mirek on this.  Mirek's command receiver is nicely done.

Bob





            
          
-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
"You see, wire telegraph is a kind of a very, very long cat.
You pull his tail in New York and his head is meowing in Los
Angeles. Do you understand this? And radio operates exactly
the same way: you send signals here, they receive them there.
The only difference is that there is no cat." - Einstein

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<Transponder Architecture - L RX.pdf>
      
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