<div dir="ltr"><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></div><div><br></div><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><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div> <br></div></div><br><div class="gmail_quote"><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">tangerinesdr@lists.tapr.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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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>
</div>
<div><br>
</div>
</div>
<br>
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