[Sls-slp] Re: Updated Prox-1 DLL book ready for your review

Tue Nov 29 23:16:00 UTC 2011

Enrico,

I intended to send it sooner, but got sick with the Flu from which I am still recovering. During this time the USA celebrated our Thanksgiving Day Holidays. (Nov 24-27)
Regarding extending the deadline from Dec 1 to Dec 8, I would gladly do so, but it is not my call. If the SLS-AD is OK with this then I will hold off from sending my update of the DLL book until then. If I do not hear from him before Dec 1, then I will still send it in to Tom Gannett to meet my action item as requested of me.

Regarding your other comments – thank you for them.
The updated version is now on the CWE with the date of Nov29 in the filenames.

1) Data rate tables – OK – now corrected in all three places.
2) Data rate pictures (figure 1.2) - OK – I had problems with placing the new picture from G.P. That is why I put in the comment. However, using your word copy of the PL book, I was able to insert it this time.
3) MRO Annex

This text came from the Electra team and reviewed by the Mars Program Chief Telecom Engineer. Apparently they think it is good enough for an informative annex. They delivered the implemention to MRO. However I have made the following changes:

I) "The Electra radio supports two standard symbol encodings" to read "The Electra radio supports two standard symbol modulations".

II) I moved the following text right up to the front of Annex E because it should be emphasized in the beginning and as you say not burried in the text. I used your formulation:

Note: for symbol rate above 512 ksps, projects interoperating with MRO should consider using NRZ-L instead of bi-phase-L unless the performance achievable with bi-phase-L is sufficient for the mission concerned.

III) For A1.7.8        Carrier Modulation

I now have put: Options c) and d) are not required for cross-support

(We should all keep in mind however that the Electra Radio is software programmable, so changes can be made in flight when required – I did not add this parenthetical – it is just for your information)

However for A1.7.6 Carrier Mode Select – I made no changes, since Electra does indeed support Supressed Carrier Mode while using BPSK (and other agencies e.g., British Space Agency plan on implementing it in their transceiver for Mars for interoperability with MRO).

Best regards,

Greg

From: "Enrico.Vassallo at esa.int<mailto:Enrico.Vassallo at esa.int>" <Enrico.Vassallo at esa.int<mailto:Enrico.Vassallo at esa.int>>
Date: Tue, 29 Nov 2011 05:56:49 -0800
To: "Kazz, Greg J (313B)" <greg.j.kazz at jpl.nasa.gov<mailto:greg.j.kazz at jpl.nasa.gov>>
Cc: "Gian.Paolo.Calzolari at esa.int<mailto:Gian.Paolo.Calzolari at esa.int>" <Gian.Paolo.Calzolari at esa.int<mailto:Gian.Paolo.Calzolari at esa.int>>, "Massimo.Bertinelli at esa.int<mailto:Massimo.Bertinelli at esa.int>" <Massimo.Bertinelli at esa.int<mailto:Massimo.Bertinelli at esa.int>>, Cosby Matthew <MCOSBY at qinetiq.com<mailto:MCOSBY at qinetiq.com>>, "sls-slp-bounces at mailman.ccsds.org<mailto:sls-slp-bounces at mailman.ccsds.org>" <sls-slp-bounces at mailman.ccsds.org<mailto:sls-slp-bounces at mailman.ccsds.org>>, "Lee, Dennis K (332C)" <dennis.k.lee at jpl.nasa.gov<mailto:dennis.k.lee at jpl.nasa.gov>>
Subject: Re: Updated Prox-1 DLL book ready for your review

Greg,

you do not give us much  chance for a in-depth review. One day is not so much especially since we are not working on CCSDS at 100% of our time.

Here's a list of things I spotted in a rush. I could not talk to Gian Paolo and therefore he may have more questions. We may be forced to come back during Agency Review if we missed other points.
Can you not extend the deadline for our comments by a week? The document is dated 21 Nov but we only got it today!

1) Data rate tables

In section "A.1.2.3.5.4 Proximity-1 Coded Symbol (Rcs) and Data Rate (Rd) Table", the column for uncoded data rates Rd is obviously wrong since Rd = .5 * Rcs should read instead Rd = Rcs and all the numbers doubled.

Same story for A.1.4.6.4 and A.1.7.9

2) Data rate pictures (figure 1.2)

Additionally, for the data rate figure instead of asking the editor to change the text, you could just replace it with the one in the PL that is already as per Exomars comments.

3) MRO Annex

In the Annex for MRO, I think that at least you should change "The Electra radio supports two standard symbol encodings" to read "The Electra radio supports two standard symbol modulations".

The Annex is marked informative and it is mostly text from Wikipedia and text books not 100% in synch with CCSDS. Sometimes, you talk about waveforms for NRZ and bi-phase, some timesabout modulations, etc. I think you should be consistent. I do not think we should put Wikipedia text and drawings in a CCSDS document. Can you not ask the diligent Dennis to provide you with a clean and reasonable text for this Annex?

Additionally, in the middle of this divulgative text (and informative annex) you entered an almost  mandatory clause:

For maximum performance with the NASA MRO Electra implementation, it is recommended that NRZ-L encoded waveforms be utilized instead of bi-phase-L (Manchester) waveforms for cross-support with the NASA MRO Electra for Proximity-1 symbol rates above 512 ksps.

Can you not say what I had proposed: for symbol rate above 512 ksps, projects interoperating with MRO should consider using NRZ-L instead of bi-phase-L unless the performance achievable with bi-phase-L is sufficient for the mission concerned.

The Annex E also has the following text:

FSK Modulation:

FSK modulation is currently not implemented on the NASA MRO Electra transceiver.

QPSK Modulation:

QPSK modulation is currently not implemented on the NASA MRO Electra transceiver.

However, in A.1.7.8 you state that FSK and OQPSK are needed to interoperate with MRO:

A1.7.8        Carrier Modulation

Bits 3-4 of the SET PL EXTENSIONS directive shall indicate the type of carrier modulation to be used:
a)        ‘00’ = No Modulation;
b)        ‘01’ = PSK;
c)        ‘10’ = FSK;
d)        ‘11’ = QPSK.

Options c) and d) are not required for cross-support except for those missions required to interoperate with NASA MRO. See Annex E.

Clearly this statement is incorrect. My proposed solution: in A1.7.8 you remove the text after cross support.

The same goes with A1.7.6 Carrier Mode Select

Bits 7-8 of the SET PL EXTENSIONS directive shall indicate the type of carrier suppression used:
a)        ‘00’ = Suppressed Carrier (Requires transmit side utilize Modulation Index of 90°and transmit/receive sides utilize Differential Mark Encoding/Decoding);
b)        ‘01’ = Residual Carrier;
c)        ‘10’ = Reserved;
d)        ‘11’ = Reserved.

Option a) is not required for cross-support except for those missions required to interoperate with NASA MRO. See AnnexE.

My proposed solution: in A1.7.6 you remove the text after cross support.

Cheers, Enrico

From:   "Kazz, Greg J (313B)" <greg.j.kazz at jpl.nasa.gov<mailto:greg.j.kazz at jpl.nasa.gov>>
To:     "Gian.Paolo.Calzolari at esa.int<mailto:Gian.Paolo.Calzolari at esa.int>" <Gian.Paolo.Calzolari at esa.int<mailto:Gian.Paolo.Calzolari at esa.int>>, "Massimo.Bertinelli at esa.int<mailto:Massimo.Bertinelli at esa.int>" <Massimo.Bertinelli at esa.int<mailto:Massimo.Bertinelli at esa.int>>, "Enrico.Vassallo at esa.int<mailto:Enrico.Vassallo at esa.int>" <Enrico.Vassallo at esa.int<mailto:Enrico.Vassallo at esa.int>>, Cosby Matthew <MCOSBY at qinetiq.com<mailto:MCOSBY at qinetiq.com>>
Cc:     "sls-slp-bounces at mailman.ccsds.org<mailto:sls-slp-bounces at mailman.ccsds.org>" <sls-slp-bounces at mailman.ccsds.org<mailto:sls-slp-bounces at mailman.ccsds.org>>
Date:   28/11/2011 18:53
Subject:        Updated Prox-1 DLL book ready for your review

________________________________

All,

Please go to the following URL to download the updated version (based upon the discussions held in Boulder and on a few follow on discussions conducted over email) of the Proximity-1 Space Data Link Layer blue book.

http://tinyurl.com/3n9qx9r

There are two new word files there and both contain the date Nov 21 embedded in the filename. One is a clean copy with out redlines. The other has the redlines.

Please let me know before Nov 30, if I have addressed your concerns adequately or if you have any further comment.I believe I have done so. On Dec 1, I will send this document on to Tom Gannett, who has already been briefed about its arrival.

Thanks again for making this book consistent with the other books.

Best regards,

Greg Kazz
Chairman SLS-SLP WG

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