[TangerineSDR] PSWS System Specification preliminary Ver 0.1

[Lyle Johnson]

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 <mailto: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
>>
>>
>>
>     -- 
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