[eagle] Re: 70 cm Eagle Receiver - Final Spur Report (at least fortoday...)

[Bill Ress]

Hi Bill,

Great to hear your response and I really look forward to your efforts. I 
know we'll all benefit by being able to design our modules with a better 
chance of first time success.

I'm not sure if or how I could contribute (maybe breadboarding or 
testing something), but you have my support.

Regards...Bill - N6GHz

Bill Tynan wrote:
> Right On Juan:
> Here is where an interface document is a nesessity. That's what I told 
> Jim I would undertake. But, I have been out of the Eagle loop for 
> months and thus didn't know that such issues were now coming up.
> An interface document should spell out power, including power quality, 
> not mere pin connections and physical fit data.
> I have a lot of catching up to do but will need a lot of help to get 
> started.
> 73,
> Bill Tynan, W3XO
>
>     ----- Original Message -----
>     *From:* Juan Rivera <mailto:juan-rivera at sbcglobal.net>
>     *To:* 'Bdale Garbee' <mailto:bdale at gag.com>
>     *Cc:* 'David Smith' <mailto:w6te at msn.com> ; 'Dave Black (Work)'
>     <mailto:dblack at mail.arc.nasa.gov> ; 'Dave Black (Home)'
>     <mailto:dblack1054 at yahoo.com> ; eagle at amsat.org
>     <mailto:eagle at amsat.org> ; 'Samsonoff at Mac. Com'
>     <mailto:%27Samsonoff at Mac.%20Com%27> ; 'Juan.Rivera (Work)'
>     <mailto:Juan.Rivera at gd-ais.com>
>     *Sent:* Sunday, June 17, 2007 12:58 PM
>     *Subject:* [eagle] Re: 70 cm Eagle Receiver - Final Spur Report
>     (at least fortoday...)
>
>     Bdale,
>
>     I certainly wouldn't suggest that no one in AMSAT understands
>     power distribution. I just can't find any detailed requirements.
>     What I have found was a spreadsheet (click here
>     <http://www.amsat.org/amsat-new/eagle/EaglePedia/uploads/1/14/Wiring.xls>)
>     that lays out all of Eagle’s wiring. There is no mention of
>     shielding or twisted pairs for the power. Both are important to
>     reduce radiated noise.
>
>     As a newcomer I am wary of aural tradition and informal meetings
>     as good tools for development of complex systems. I think
>     everything needs to be written down in unambiguous requirements
>     documents, starting at the top level. This current exercise with
>     the 70 cm receiver is a good test of the current processes and
>     procedures.
>
>     I’ve glanced at John's new receiver specifications and I don’t see
>     any reference to input power or the EMI environment that the
>     receiver must work in. How can it be designed or tested if that
>     environment has not been specified as a requirement? It’s not
>     John’s fault. He has nothing to base it on. That’s where the top
>     level requirements would give him something to work with.
>     Everything needs to start at the top and work down. Not from the
>     bottom up.
>
>     73,
>
>     Juan
>
>     -----Original Message-----
>     From: Bdale Garbee [mailto:bdale at gag.com]
>     Sent: Sunday, June 17, 2007 10:04 AM
>     To: juan-rivera at sbcglobal.net
>     Cc: eagle at amsat.org; David Smith; Dave Black (Work); Dave Black
>     (Home); Samsonoff at Mac. Com; Juan.Rivera (Work)
>     Subject: Re: [eagle] 70 cm Eagle Receiver - Final Spur Report (at
>     least fortoday...)
>
>     On Sun, 2007-06-17 at 08:48 -0700, Juan Rivera wrote:
>
>     > I've completed my testing and analysis of the spurs that appeared in
>
>     > the IF output of the 70 cm Eagle Receiver prototype. I believe I know
>
>     > the source and the cause of all of them and how they can be
>     eliminated
>
>     > or rendered harmless.
>
>     Nice work.
>
>     Reading your report, two things strike me, neither of which I consider
>
>     myself an expert on in AMSAT or elsewhere, but both of which I'll
>
>     mention to help motivate the review of power system requirements you
>
>     clearly hope comes next/soon.
>
>     The first is that I think AMSAT does understand most if not all of the
>
>     issues you're warning against regarding DC distributiong wiring. Some
>
>     care was taken, for example, in planning pinouts of the 15-pin
>     connector
>
>     on the spacecraft bus side of the CAN-Do! widget, and in the proposed
>
>     wiring harness design from the Black Forest meeting.
>
>     The second is that I think more work is going to be required to ensure
>
>     receivers behave reasonably in the presence of supply noise. For
>
>     various reasons, as others have already alluded, I wouldn't count
>     on the
>
>     Eagle power bus being very quiet.
>
>     Bdale, from Edinburgh
>
>     ------------------------------------------------------------------------
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>     Via the Eagle mailing list courtesy of AMSAT-NA
>     Eagle at amsat.org
>     http://amsat.org/mailman/listinfo/eagle
>
> ------------------------------------------------------------------------
>
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>