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<p>Okay. De-multiplexing is a much better and less confusing
terminology. As you stated, decimation is a DSP thing and
channelizing the downlink payload has nothing to do with DSP (all
the DSP has already been down in order to deliver payload
packets).<br>
</p>
<p>Ron W6RZ<br>
</p>
<div class="moz-cite-prefix">On 1/25/19 16:17, Michelle Thompson
wrote:<br>
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cite="mid:CACvjz2Vpz5b+NP1XcfOTvpN71FZViXQEjjXxTuod85GvqaQ27A@mail.gmail.com">
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<div dir="ltr">To me, decimation is what we do in order to
channelize in the payload. <br>
<br>
I don't think that's exactly what I'm being asked about in the
ground station receiver, though. <br>
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data-smartmail="gmail_signature">
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<div dir="ltr">-Michelle W5NYV<br>
<br>
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<div dir="ltr" class="gmail_attr">On Fri, Jan 25, 2019 at 4:14
PM Ron Economos <<a href="mailto:w6rz@comcast.net"
moz-do-not-send="true">w6rz@comcast.net</a>> wrote:<br>
</div>
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<p>I'm not sure we are talking about the same thing yet. So
what exactly do you expect to decimate and why?<br>
</p>
<p>Ron W6RZ<br>
</p>
<div class="gmail-m_8520444453280004698moz-cite-prefix">On
1/25/19 16:07, Michelle Thompson wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">The beginning of wisdom being the
definition of terms and all, it would be good to make
sure we're all talking about the same thing. <br>
<br>
So far, I've used LNBs and USRPs for receive, with the
LNB doing an IF at 618MHz (LNB-on-a-Stick) and giving
reasonable performance. <br>
<br>
Decimation to me is a DSP thing, or used to reduce power
consumption when you don't need to sample as high as you
can. <br>
<br clear="all">
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class="gmail-m_8520444453280004698gmail_signature">
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<div dir="ltr">-Michelle W5NYV<br>
<br>
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<div dir="ltr"
class="gmail-m_8520444453280004698gmail_attr">On Fri,
Jan 25, 2019 at 3:52 PM Ron Economos via
Ground-Station <a
class="gmail-m_8520444453280004698moz-txt-link-rfc2396E"
href="mailto:ground-station@lists.openresearch.institute"
target="_blank" moz-do-not-send="true"><ground-station@lists.openresearch.institute></a>
wrote:<br>
</div>
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0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
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<p>The standard IF for DVB-S2 receivers is 950 to
2150 MHz.</p>
<p>DB6NT was selling a down-converter from
10489-10500 MHz to 1129-1140 MHz for P4A.</p>
<p><a
class="gmail-m_8520444453280004698gmail-m_-6643074664132559776moz-txt-link-freetext"
href="https://shop.kuhne-electronic.com/kuhne/en/shop/new/MKU+LNC+10+OSCAR+P4A/?card=1832"
target="_blank" moz-do-not-send="true">https://shop.kuhne-electronic.com/kuhne/en/shop/new/MKU+LNC+10+OSCAR+P4A/?card=1832</a></p>
<p>I'm not sure what decimation has to do with
receiving DVB-S2. The entire 10 MHz signal needs
to be demodulated. Individual baseband frames will
be selected for processing, but I call that
de-multiplexing.<br>
</p>
<p>Ron W6RZ<br>
</p>
<div
class="gmail-m_8520444453280004698gmail-m_-6643074664132559776moz-cite-prefix">On
1/25/19 15:32, David Vieira via Ground-Station
wrote:<br>
</div>
<blockquote type="cite">
<div
class="gmail-m_8520444453280004698gmail-m_-6643074664132559776ydp1f38d99eyahoo-style-wrap">
<div>Michelle - Thanks for posting. I'll frame
some of the questions.<br>
</div>
<div><br>
</div>
<div>Typical 10 GHz terrestrial contesting rigs
are Heterodyne; that is a Mixer works with a
Local Oscillator (LO) to take the RF down to
an IF (Intermediate Frequency).</div>
<div>For an SDR, that IF can be digitized by an
Analog-Digital Converter.</div>
<div><br>
</div>
<div>The most popular IF for contesting/SSB rigs
is 144 MHz. </div>
<div>For a data BW of 10 MHz that may or may not
be a fast enough IF carrier. If we can
digitize and recover the data, it would allow
a lot of re-use of existing equipment.</div>
<div><br>
</div>
<div>I've heard suggestions/proposals up to the
1.2 GHz Ham band.</div>
<div>In some sense, the IF carrier could be
144/220/440/915/1200 MHz, or even any Non-Ham
frequency in between.</div>
<div><br>
</div>
<div>There are a lot of proof of existence
designs for a 10 GHz Mixed down to an IF; and
lots of off the shelf ADC dev-boards. (catch
me off thread for details).</div>
<div><br>
</div>
<div>Some questions I have are: </div>
<div>---from an FPGA side of the SDR, what data
rate(s) can the FPGA absorb in to a
decimator? </div>
<div><br>
</div>
<div>Must we decide upfront on a single
frequency; or </div>
<div>preferably allow flexibility in the RF
front end design (ie, Mixer, PLL and Local
Oscl hardware choices) by allowing a wide and
programmable variety of ADC and decimation
rates?</div>
<div><br>
</div>
<div>{This is where RF and Digital folks must
communicate across walls.} ;-)</div>
<div><br>
</div>
<div>Comments welcome.</div>
<div><br>
</div>
<div>regards,</div>
<div>David</div>
<div>KI6CLA</div>
<div><br>
</div>
<div><br>
</div>
</div>
<div
id="gmail-m_8520444453280004698gmail-m_-6643074664132559776ydp40e62e6byahoo_quoted_8708381549"
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<div>
<div> On Friday, January 25, 2019, 2:41:54 PM
PST, Michelle Thompson via Ground-Station <a
class="gmail-m_8520444453280004698gmail-m_-6643074664132559776moz-txt-link-rfc2396E"
href="mailto:ground-station@lists.openresearch.institute"
target="_blank" moz-do-not-send="true"><ground-station@lists.openresearch.institute></a>
wrote: </div>
<div><br>
</div>
<div><br>
</div>
<div>
<div
id="gmail-m_8520444453280004698gmail-m_-6643074664132559776ydp40e62e6byiv6388574106">
<div dir="ltr">
<div dir="ltr">While we are striving to
enable all sorts of wonderful designs
by putting prototypes into GNU Radio,
a central goal is to design our own
hardware.<br>
<br>
We've had a lot of progress on the
protocol and algorithm front (GSE,
LDPC, some of the polyphase). <br>
<br>
Some fundamental decisions about our
own hardware need to be made.<br>
<br>
When we receive, we expect to have to
decimate. This is because we are
receiving at a relatively high
frequency (10GHz).<br>
<br>
Our bandwidth is (up to) 10MHz. For
DVB-S2/X, we fix our sampling rate,
depending on what bandwidth we want to
support. We have a lot of freedom
here.<br>
<br>
Picking the right frequencies for the
receive chain is therefore important.<br>
<br>
What are our options? <br>
<br>
What options make the best sense?<br>
<br>
I'd like to build and test as soon as
possible, so let's get some discussion
going.<br>
<br>
<div>
<div dir="ltr"
class="gmail-m_8520444453280004698gmail-m_-6643074664132559776ydp40e62e6byiv6388574106gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">-Michelle
W5NYV<br>
<br>
<div dir="ltr"><br>
</div>
</div>
</div>
</div>
</div>
</div>
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