[TangerineSDR] PSWS System Specification preliminary Ver 0.1

Sat May 4 10:58:01 EDT 2019

Hi Lyle,  I forwarded your request on to Nathaniel to see if he or NJIT has
anything.  Perhaps
they wrote a grant proposal that might have this information?

-- Tom, N5EG

On Thu, May 2, 2019 at 7:07 PM Lyle Johnson <kk7p4dsp at gmail.com> wrote:

>
> On 5/2/19 2:05 PM, Tom McDermott wrote:
>
> Hi Lyle,  thanks for the comments!
>
> There is no other document about the Space Weather Station System.  What
> in particular would
> that document cover?  Use Cases ?  Narrative description?   The central
> server?
> We could ask the NJIT folks to draft something if we can tell them what we
> need.
>
> 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.
>
> How does measuring HF signals and a co-located magnetometer help meet the
> objectives of the system?
>
> If I am a radio amateur, what benefits derive to the Amateur radio
> community by this system and/or any particular individual's participation?
>
>
> More comments to follow :-)
>
> Lyle
>
>
> On the RF module...  the plug-on filter could be called plug-in filter. It
> could even be an in-line filter.
> What would be more clear?
>
> I think the ENOB refers to the SNR of the converter, not the dynamic
> range.  Perhaps this view
> is not shared by everyone.
>
> If one were to integrate 2 sets of time-domain measurements, the noise
> floor would drop by 3 dB compared
> to the peak signal.  As more frames are integrated the noise floor
> continues to drop until at some
> point the spurious signals begin to emerge.  In the analog domain these
> are 3rd order products. In the
> digital domain they are spurious signals (due to nonlinearities, clocks,
> etc.)   The ADC driver we
> are familiar with has 3rd order products DR of about 91.5 dB.  The ADC
> dynamic range is specified as SFDR
> using a large FFT (essentially integrating away a lot of noise), and it's
> close to 100 dB.
>
> So what is the right vocabulary or method to specify this that everyone
> will understand?
> I did not find ENOB specs, but my understanding is the 14-bit ADC has
> about the same ENOB as the 16-bit ADC.
> If you found or have ENOB data on the 14-bit converter, that would be
> helpful.
>
> On the magnetometer, we did not agree on the specifications of the
> magnetometer with the research team yet.
> The desired one has a bare sensor cost exceeding the entire project. So
> we've been looking for cheaper
> alternatives (which don't have as much resolution by a factor of 6).
> Scotty and I talked with Univ of Michigan (?)
> students on the $20 unit that they found (it's a commercial product, uses
> SPI). It has about 1-dgreee orthogonality
> error.
>
> The host could easily handle SPI, I2C, or other since it's such a slow
> rate and time precision is unimportant.
> I tried to capture that possibility in section 6, first paragraph.  Is
> there better wording to use?
>
> -- Tom, N5EG
>
>
>
>
>
>
>
> On Thu, May 2, 2019 at 9:29 AM Lyle Johnson via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
>> Hello Tom!
>>
>> 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?
>>
>> 5. RF Module
>>
>> 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.
>>
>> 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.
>>
>>
>> 7. Host Computer
>>
>> 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.
>>
>> 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.
>>
>> ---
>>
>> Just some initial thoughts,
>>
>> Lyle
>> On 5/2/19 7:47 AM, Tom McDermott via TangerineSDR wrote:
>>
>> Attached in PDF format is a very preliminary system specification for the
>> Personal Space Weather Station (PSWS).
>>
>> There are lots of open issues and questions at this point, the document
>> tries to highlight a few of the key ones.
>>
>> It would be nice to have several sets of eyeballs look this over before
>> we advance it any further.
>>
>> -- Tom, N5EG
>>
>>
>>
>> --
>> TangerineSDR mailing list
>> TangerineSDR at lists.tapr.org
>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>
>
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