Fwd: Re: Fwd: Re: [Sis-csi] IP Header Compression

[Ed Greenberg]

Dave,  From the write up I need to assume certain things:
1)  that the uplink decoder is the CCSDS BCH Code using triple error 
detection (no coding gain, high symbol SNR, continuous small block of bytes 
validation)
2)  that the "frame" handling requires the UDP packet area (which contains 
the data of interest)  to have a fixed offset from the frame start.

If a hardware decoder is incorporated into the frond end processing, the 
only difference between this and the CCSDS is the number of bits that need 
to be received before decoding the command.  However, if the mission moves 
away from near earth or high throughput rates are required, then the 
processing would get a little more complex (including adding an code 
decoder) and the number of bits to achieve code lock and then frame lock 
might increase substantially.   This topic is supposed to be addressed by 
the High Rate Uplink BOF.
  Ed




At 10:09 AM 9/8/2005 -0400, Dave Israel wrote:
>All,
>
>Here's what has been provided to me by folks that worked on GPM...
>
>Dave
>
>
>
>>SBRS: 3.7
>>MID: 4321226
>>X-BrightmailFiltered: true
>>X-Brightmail-Tracker: AAAAAA==
>>X-IronPort-AV: i="3.96,177,1122868800";
>>    d="doc'32?scan'32,208,217,32"; a="4321226:sNHT114010012"
>>X-Sender: jmarquar at pop700.gsfc.nasa.gov
>>X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1
>>Date: Wed, 07 Sep 2005 16:51:55 -0400
>>To: Dave Israel <dave.israel at nasa.gov>,
>>         "Jane K. Marquart" <Jane.K.Marquart at nasa.gov>,
>>         Jonathan.J.Wilmot at nasa.gov, Freemon.Johnson at nasa.gov
>>From: Jane Marquart <Jane.Marquart at nasa.gov>
>>Subject: Re: Fwd: Re: [Sis-csi] IP Header Compression
>>
>>Dave,
>>
>>The most important thing when sending "special commands" (or hardware 
>>commands....there are lots of different names) is that the actual command 
>>be in a FIXED location within the packet/frame/whatever.  It should not 
>>have to go through any software processing, but be usable "right away", 
>>i.e. in the comm subsystem and/or on arrival at the subsystem.  The 
>>hardware is essentially preprogrammed   I've attached I wrote up during 
>>GPM.  "Bus commands" were special commands to subsystems other than the 
>>COMM (since they had to go over the s/c bus).
>>If you have any questions, let me know.
>>
>>Jane
>
>
>
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Progress is impossible when you always do things the way they have always 
been done.