Fwd: Re: [Sls-rfm] [Sls-slp] Table form of Prox-1 Phy Layer Data Rate Requirements and comments from NASA GSFC
Greg Kazz
greg.j.kazz at jpl.nasa.gov
Thu Mar 24 13:16:30 UTC 2005
To: Prox-1 Build-2 WG members and Electra Project,
Victor Sank's (NASA GSFC) comments to the Prox-1 Physical Layer Pink Sheets
follows.
Greg
>Date: Thu, 24 Mar 2005 08:44:47 +0100
>From: Enrico.Vassallo at esa.int
>Subject: Re: [Sls-rfm] [Sls-slp] Table form of Prox-1 Phy Layer Data Rate
> Requirements
>To: "Victor J. Sank" <victor.sank at gsfc.nasa.gov>
>Cc: Greg J Kazz <Greg.J.Kazz at jpl.nasa.gov>, Dennis.K.Lee at jpl.nasa.gov,
> Wai Fong <wai.fong at gsfc.nasa.gov>
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> 8, 2004) at 03/24/2005 08:44:49 AM
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>
>Victor,
>
>so far we have received your comments and Don's comments, which I endorsed
>from the ESA point of view. None were submitted in RID forms but I don't
>believe we need to be so formal.
>I will forward your e-mail to the RFM WG and I believe that Greg will do the
>same with his WG. We will discuss all inputs at the joint meeting.
>
>Regards, Enrico
>
>
>
>|---------+--------------------------->
>| | "Victor J. Sank"|
>| | <victor.sank at gsf|
>| | c.nasa.gov> |
>| | |
>| | 23/03/2005 23:07|
>| | |
>|---------+--------------------------->
>
> >-------------------------------------------------------------------------------------------------------------------------------|
> |
> |
> | To: Greg J Kazz <Greg.J.Kazz at jpl.nasa.gov>,
> Dennis.K.Lee at jpl.nasa.gov |
> | cc: Enrico.Vassallo at esa.int,
> wai.fong at gsfc.nasa.gov
> |
> | Subject: Re: [Sls-rfm] [Sls-slp] Table form of Prox-1 Phy
> Layer Data Rate Requirements |
>
> >-------------------------------------------------------------------------------------------------------------------------------|
>
>
>
>
>Greg, Dennis,
>Administrative:
> Please be carful to put a proper date in the document header where it
>says DATE:
>Your document has an Automatic date which is no good, it shows current data
>every time someone opens the document instead of the actual intended creation
>date.
>
>Technical:
> prox1_datarage_rqmts_pinksheets 3-21-05 DL.doc states
>"Because its symbol clock is derived by dividing down the USO frequency which
>in most cases is not an exact multiple of the Prox-1 specified data rates,
>Electra dithers the number of samples per symbol to insure that the average
>symbol rate is equal to the value in the specification in order to achieve an
>average symbol rate matching the Prox-1 specification. This can cause a
>fairly large deviation in symbol period from one symbol to another (up to 7%
>[1]), in particular when there are relatively few samples per symbol at the
>high symbol rates."
> Suggest you change the point of view in the Prox 1 specification.
>Use the oscillator as the defining item for the data rate and accept that it
>will not be exactly 1 Kbps or whatever the goal is. For example, for ST5 we
>have a 9.625 MHz oscillator that is used to define the data rates. The rates
>are Rj = 9.625 MHz/n, where n is an integer. Our 100 Kbps data rate is
>actually 100.26 Kbps, 200 Kbps is actually 200.52 Kbps and 1 Kbps is actually
>1.0001 Kbps. % jitter 0.26% worst case in these examples. In our case, the
>bit synch on the receive side can easily track the actual data rate even when
>set to the approximate value. I assume, but do not know for sure, that in
>the case of Prox1 equipment, the situation is similar. By doing things this
>way, the jitter is very low which is important to the spectrum purity,
>receiver and receiving bit synch. The trade off is low jitter but maybe some
>tracking loop stress. We have not had acquisition problems even when setting
>the approximate data rate.
> I am suggesting that the receiving bit synch can handle the loop
>stress better than the jitter.
>
>Enrico,
> I do not want to put this in an official RID unless you think it
>should be.
>
>Victor
>
>
>
>Thanks,
>Victor
>
>
>At 09:17 AM 3/22/2005 +0100, Enrico.Vassallo at esa.int wrote:
> For consideration at the joint meeting in Athens.
>
> Regards, Enrico
>
> ----- Forwarded by Enrico Vassallo/esoc/ESA on 22/03/2005 09:17 -----
> |---------+--------------------------------->
> | | Greg Kazz |
> | | <greg.j.kazz at jpl.nasa.|
> | | gov> |
> | | Sent by: |
> | | sls-slp-bounces at mailma|
> | | n.ccsds.org |
> | | |
> | | |
> | | 22/03/2005 06:00 |
> | | |
> |---------+--------------------------------->
>
>
> >-------------------------------------------------------------------------------------------------------------------------------|
>
> |
> |
> | To: sls-slp at mailman.ccsds.org
> |
> | cc:
> |
> | Subject: [Sls-slp] Table form of Prox-1 Phy Layer Data Rate
> Requirements |
>
>
> >-------------------------------------------------------------------------------------------------------------------------------|
>
>
>
>
>
> All,
>
> Attached is a file containing the Prox-1 Physical Layer Pink Sheets -
> Data
> Rate Requirements in Tabular Form from Dennis Lee. These pink sheets
> contain the same information as the previous set, however reformated
> into a
> table so that it's easier to understand. These are the pink sheets that
> I
> plan to discuss at our joint meeting with RF&MOD in Athens.
>
> Please let me know if you have any questions or concerns and cc: Dennis
> Lee
>
> best regards,
>
> Greg Kazz
> Chairman Prox-1 Build-2 WG(See attached file:
> prox1_datarate_rqmts_pinksheets
> 3-21-05 DL.doc)_______________________________________________
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>
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>
>Victor J. Sank Code 567 / MEI
>NASA Goddard Space Flight Center
>Code 567, Building 19, Room S044
>Greenbelt, MD 20771
>Email: Victor.Sank at gsfc.nasa.gov
>Phone: 301 286 2645
>pager: 301 207 1863
>Cell: 240 353 8056
>Fax: 301 286 1750
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