<html>
<head>
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
</head>
<body>
<p>Thanks, Nicoḷ. Yes, there is more than one way to do this, and
we could have expressed things in terms of received watts. The
approach we took was to simplify the mean and variance expressions
and use as few parameters as possible. In this way, the mean
depends only on rho (the fade) and ns (the mean number of absorbed
photons per signal slot). This makes it intuitively related to
the photon counting model, and allows straightforward plotting
using photons/bit, which is the common metric by which to measure
optical coding performance.</p>
<p>One can do things in watts, and translate to n_s, if you find
that more intuitive. We didn't find that as convenient, however.
For example, if we had expressed the model so that the mean signal
was Ps in incident watts, and used that as the free parameter in
the simulations, the variance expressions would include an eta/ (h
nu) term, which would require knowing the frequency and quantum
efficiency. That's not a problem, but it is two more parameters
than are needed in the formulation we suggested. We think it may
be more easier to run simulations with the normalized model, and
then plug in these other parameters later if you want to plot vs.
received watts for an APD with a specific responsivity (or quantum
efficiency and frequency).</p>
<p>Anyway, that was our thinking.<br>
</p>
<p> ----Jon<br>
</p>
<div class="moz-signature"><strong>Jon Hamkins</strong><br>
Lead Technologist<br>
33 | Communications, Tracking, and Radar Division<br>
<strong>O</strong> 818-354-4764 | <strong>M</strong>
626-658-6220 <br>
<br>
<strong>JPL</strong> | jpl.nasa.gov
</div>
<div class="moz-cite-prefix">On 4/22/2020 12:28 AM, Nicolo Mazzali
(external) wrote:<br>
</div>
<blockquote type="cite"
cite="mid:11880_1587540504_5E9FF218_11880_28_1_OF9B8F4BAD.236BC283-ONC1258552.002742C6-C1258552.00290CA7@esa.int">
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
<span style=" font-size:10pt;font-family:sans-serif">Dear Jon, </span>
<br>
<br>
<span style=" font-size:10pt;font-family:sans-serif">Thanks for
summarizing
the channel model and the parameters' values.</span>
<br>
<span style=" font-size:10pt;font-family:sans-serif">In principle
we
are fine with them, but we would like to understand the
motivation for
having all the powers (i.e., the signal power and noise
variances) normalized
as dimensionless quantities, instead of having them in watts -
which is
probably more intuitive, at least from an engineering point of
view. Could
you please confirm that this is indeed the case and elaborate a
bit on
your choice?</span>
<br>
<br>
<span style=" font-size:10pt;font-family:sans-serif">Thanks a lot
in
advance!</span>
<br>
<br>
<span style=" font-size:10pt;font-family:sans-serif">Kind regards,
<br>
</span>
<p style="margin-top:0px;margin-Bottom:0px"><span style="
font-size:8pt;color:#808080;font-family:Verdana"><b>Modis
for ESA - European Space Agency</b></span><span style="
font-size:12pt;font-family:Tms Rmn">
</span><span style="
font-size:8pt;color:#00a1e0;font-family:Verdana"><br>
<br>
Nicoḷ Mazzali, PhD </span><span style="
font-size:8pt;color:#808080;font-family:Verdana"><br>
Communication Systems & Technologies Engineer</span><span
style=" font-size:12pt;font-family:Tms Rmn">
</span><span style="
font-size:8pt;color:#808080;font-family:Verdana"><br>
<br>
Telecommunications Section (TEC-ESC)</span><span style="
font-size:12pt;font-family:Tms Rmn">
</span><span style="
font-size:8pt;color:#808080;font-family:Verdana"><br>
Radio Frequency Systems Division (TEC-ES)</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style="
font-size:8pt;color:#808080;font-family:Verdana">Directorate
of Technology, Engineering & Quality (D/TEC)<b><br>
<br>
<br>
ESTEC</b><br>
Keplerlaan 1, PO Box 299<br>
NL-2200 AG Noordwijk, The Netherlands</span><span style="
font-size:8pt;color:#0082bf;font-family:Verdana"><u><br>
</u></span><a href="mailto:nicolo.mazzali@esa.int"
moz-do-not-send="true"><span style="
font-size:8pt;color:#0082bf;font-family:Verdana"><u>nicolo.mazzali@esa.int</u></span></a><span
style=" font-size:8pt;color:#808080;font-family:Verdana">
| </span><a href="http://www.esa.int/" moz-do-not-send="true"><span
style=" font-size:8pt;color:#8f8f8f;font-family:Verdana"><u>www.esa.int</u></span></a><span
style=" font-size:8pt;color:#808080;font-family:Verdana"><br>
T +31 71 56 53215</span></p>
<br>
<br>
<br>
<br>
<span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</span><span style="
font-size:9pt;font-family:sans-serif">"Jon
Hamkins via SLS-OPT" <a class="moz-txt-link-rfc2396E" href="mailto:sls-opt@mailman.ccsds.org"><sls-opt@mailman.ccsds.org></a></span>
<br>
<span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style="
font-size:9pt;font-family:sans-serif"><a class="moz-txt-link-rfc2396E" href="mailto:SLS-OPT@mailman.ccsds.org">"SLS-OPT@mailman.ccsds.org"</a>
<a class="moz-txt-link-rfc2396E" href="mailto:SLS-OPT@mailman.ccsds.org"><SLS-OPT@mailman.ccsds.org></a></span>
<br>
<span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Date:
</span><span style="
font-size:9pt;font-family:sans-serif">15/04/2020
17:20</span>
<br>
<span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style="
font-size:9pt;font-family:sans-serif">[SLS-OPT]
O3K channel model</span>
<br>
<span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Sent
by: </span><span style="
font-size:9pt;font-family:sans-serif">"SLS-OPT"
<a class="moz-txt-link-rfc2396E" href="mailto:sls-opt-bounces@mailman.ccsds.org"><sls-opt-bounces@mailman.ccsds.org></a></span>
<br>
<hr noshade="noshade">
<br>
<br>
<br>
<span style=" font-size:12pt">Attached is the O3K channel model we
discussed yesterday. It also contains a suggestion for how to
state
the O3K coding performance. I welcome your comments. If we
can agree to the model in the next week or so, each agency may
be able
to begin simulating with it and discuss some initial results at
the May
teleconferences.</span>
<br>
<span style=" font-size:12pt">A few notes:</span>
<ul>
<li><span style=" font-size:12pt">I am suggesting we study 10
Gsps, 78.125
Msps, and 1.22 Mbps, since those include the highest and
lowest data rates
and one in the middle.</span>
</li>
<li><span style=" font-size:12pt">I don't have a good suggestion
for the
TIA noise density at 1.22 Msps. Dirk, would you be able to
supply
a number?</span>
</li>
<li><span style=" font-size:12pt">I have algebraically
simplified the expressions
for the means and variances. You can compare the model to
the expressions
Dariush presented on yesterday (p. 5), and check my algebra.</span>
</li>
<li><span style=" font-size:12pt">I have included the fading
parameter
as well. Just set rho=1 if you want no fading.</span></li>
</ul>
<span style=" font-size:12pt">
----Jon</span>
<br>
<span style=" font-size:12pt">-- <b><br>
Jon Hamkins</b><br>
Lead Technologist<br>
33 | Communications, Tracking, and Radar Division<b><br>
O</b> 818-354-4764 | <b>M</b> 626-658-6220 <br>
<b><br>
JPL</b> | jpl.nasa.gov [attachment
"2020-04-15-O3K-channel-model.pptx"
deleted by Nicolo Mazzali/estec/ESA] </span>
<br>
<tt><span style=" font-size:10pt">_______________________________________________<br>
SLS-OPT mailing list<br>
<a class="moz-txt-link-abbreviated" href="mailto:SLS-OPT@mailman.ccsds.org">SLS-OPT@mailman.ccsds.org</a><br>
</span></tt><a
href="https://mailman.ccsds.org/cgi-bin/mailman/listinfo/sls-opt"
moz-do-not-send="true"><tt><span style=" font-size:10pt">https://mailman.ccsds.org/cgi-bin/mailman/listinfo/sls-opt</span></tt></a><tt><span
style=" font-size:10pt"><br>
</span></tt>
<br>
<br>
<pre>This message is intended only for the recipient(s) named above. It may contain proprietary information and/or
protected content. Any unauthorised disclosure, use, retention or dissemination is prohibited. If you have received
this e-mail in error, please notify the sender immediately. ESA applies appropriate organisational measures to protect
personal data, in case of data privacy queries, please contact the ESA Data Protection Officer (<a class="moz-txt-link-abbreviated" href="mailto:dpo@esa.int">dpo@esa.int</a>).
</pre>
</blockquote>
</body>
</html>