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<div class="moz-cite-prefix">On 5/2/19 2:05 PM, Tom McDermott wrote:<br>
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<div>Hi Lyle, thanks for the comments!</div>
<div><br>
</div>
<div>There is no other document about the Space Weather Station
System. What in particular would</div>
<div> that document cover? Use Cases ? Narrative
description? The central server? <br>
</div>
<div>We could ask the NJIT folks to draft something if we can
tell them what we need.<br>
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<p>What is the Space Weather Station System? What is it trying to
measure/determine/catalog i.e., what are the objectives of the
system? How many stations and/or how large a geographical area is
needed for a critical mass to make it useful to meet the
objectives of the system.</p>
<p>How does measuring HF signals and a co-located magnetometer help
meet the objectives of the system?</p>
<p>If I am a radio amateur, what benefits derive to the Amateur
radio community by this system and/or any particular individual's
participation?</p>
<p><br>
</p>
<p>More comments to follow :-)</p>
<p>Lyle<br>
</p>
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<div>On the RF module... the plug-on filter could be called
plug-in filter. It could even be an in-line filter.</div>
<div> What would be more clear?</div>
<div><br>
</div>
<div>I think the ENOB refers to the SNR of the converter, not
the dynamic range. Perhaps this view</div>
<div>is not shared by everyone.</div>
<div><br>
</div>
<div>If one were to integrate 2 sets of time-domain
measurements, the noise floor would drop by 3 dB compared</div>
<div>to the peak signal. As more frames are integrated the
noise floor continues to drop until at some</div>
<div>point the spurious signals begin to emerge. In the analog
domain these are 3rd order products. In the</div>
<div>digital domain they are spurious signals (due to
nonlinearities, clocks, etc.) The ADC driver we<br>
</div>
<div>are familiar with has 3rd order products DR of about 91.5
dB. The ADC dynamic range is specified as SFDR</div>
<div>using a large FFT (essentially integrating away a lot of
noise), and it's close to 100 dB.</div>
<div><br>
</div>
<div>So what is the right vocabulary or method to specify this
that everyone will understand?</div>
<div>I did not find ENOB specs, but my understanding is the
14-bit ADC has about the same ENOB as the 16-bit ADC.</div>
<div>If you found or have ENOB data on the 14-bit converter,
that would be helpful.</div>
<div><br>
</div>
<div>On the magnetometer, we did not agree on the specifications
of the magnetometer with the research team yet.</div>
<div>The desired one has a bare sensor cost exceeding the entire
project. So we've been looking for cheaper</div>
<div>alternatives (which don't have as much resolution by a
factor of 6). Scotty and I talked with Univ of Michigan (?)</div>
<div> students on the $20 unit that they found (it's a
commercial product, uses SPI). It has about 1-dgreee
orthogonality</div>
<div> error. <br>
</div>
<div><br>
</div>
<div>The host could easily handle SPI, I2C, or other since it's
such a slow rate and time precision is unimportant.</div>
<div>I tried to capture that possibility in section 6, first
paragraph. Is there better wording to use?</div>
<div><br>
</div>
<div>-- Tom, N5EG</div>
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<div dir="ltr" class="gmail_attr">On Thu, May 2, 2019 at 9:29 AM
Lyle Johnson via TangerineSDR <<a
href="mailto:tangerinesdr@lists.tapr.org"
moz-do-not-send="true">tangerinesdr@lists.tapr.org</a>>
wrote:<br>
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<p>Hello Tom!</p>
<p>Is there a document that describes the Space Weather
Station System so I can more easily see where the weather
station fits into the overall scheme of things?</p>
<p>5. RF Module</p>
<p>I worry about pluggable filter modules because that
implies custom stuff and thus a need for someone to design
it/them. Still, an external filter module (small Hammond
or other shielded box with 50-ohm in and out) could always
be used so this is probably a Good Thing to include.</p>
<p>Not sure what 88 dB dynamic range for directly sampled
signals means. A perfect 14 bit ADC would have about 84
dB raw dynamic range. The LTC2208, still one of the best
16-bit ADCs I think, has an effective number of bits of
just under 13 (12.6 is the number I've seen) though the
spec sheet claims a Spurious Free DR of 100 dB.</p>
<p><br>
</p>
<p>7. Host Computer</p>
<p>Since the magnetometer specification is so vague, and
since it only needs to be processed once per second (and I
assume a few microseconds or even milliseconds of
uncertainty in that sampling would have negligible impact)
I suspect the host computer is much better suited to
collect and format the data. If the interface is some
standard thing easily implemented by a standard FPGA
library (like a SPI or SPI port) then the FPGA could
gather the raw samples.</p>
<p>Hopefully a magnetometer thingy can be located that meets
whatever the needs are for it, that is already equipped
with an interface that can be read by a PC over a standard
interface.</p>
<p>---</p>
<p>Just some initial thoughts,</p>
<p>Lyle<br>
</p>
<div class="gmail-m_2136238142676196779moz-cite-prefix">On
5/2/19 7:47 AM, Tom McDermott via TangerineSDR wrote:<br>
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<div>Attached in PDF format is a very preliminary system
specification for the Personal Space Weather Station
(PSWS).</div>
<div><br>
</div>
<div>There are lots of open issues and questions at this
point, the document tries to highlight a few of the
key ones.</div>
<div><br>
</div>
<div>It would be nice to have several sets of eyeballs
look this over before we advance it any further.</div>
<div><br>
</div>
<div>-- Tom, N5EG</div>
<div><br>
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