[eagle] Re: CAN-Do-Too! ??????????
wb4gcs at amsat.org
Mon Jul 9 19:47:13 PDT 2007
I'm exhausted. More detailed response tomorrow. YOu make good points,
we need to decide how to proceed.
Thanks & 73,
wb4gcs at amsat.org
Bill Ress wrote:
> Jim Sanford wrote:
>> 4. EMI Spec: You put a gun to my head, and I'm going to pull out
>> the MIL-STD, which is probably overkill, but MAYBE NOT. I'd really
>> prefer that one of you guiys current in the INDUSTRIAL world take on
>> this task and come up with something good enough and reasonable. In
>> general, I'd like to eliminate as much mass and extra "touch" labor
>> in the assembly process (multiple shields) as possible. Bob Davis:
>> Please weigh in here, if the possible milled modules simplify this
>> issue, please enlighten us.
> Jim, I think an EMI spec pulled out of a MIL-STD would be an over kill
> effort and likely not representative of "our" real world. What we need
> is not assumptions but data reflecting what the hardware does. The
> problem is that we don't have the hardware - and that's my issue. The
> power distribution circuits are what I call a "top level" subsystem
> which feeds "everyone." Instead of working on the circuitry that will
> run from it and trying to "imagine" what we can expect, let's focus on
> breadboarding the key power distribution circuits and get some hard
> data so we know what we're working with.
> I'll again reiterate (as I have several times in the past) the same
> thing for the satellite's 10 MHz reference. It's another top level
> "subsystem" that will feed "all" LO's. Instead of guessing what we'll
> be working with, let's get it defined too.
> (I'm proposing we put that one to bed and use the time tested, well
> defined, high stability, low noise HP (OK - Agilent) 10811 series of
> reference standards used in most of their test instruments. If that
> won't cut it - someone please tell me why!)
>> 7. Requirements: Bob McGwier is correct, we really did start with a
>> very top-level requirements document. It is not perfect (Bob has
>> hated it from the word go), but can be found on EaglePedia under
>> Functional Requirements. It is also in need of updating, after the
>> October BoD decision. On my list to do. Like you, I have finite
>> energy and time, but it is on my list. I think John did an EXCELLENT
>> job of documenting the UHF Receiver requirements based on what he
>> knew. The need for an EMI spec was not obvious, but is now, thanks
>> to Juan's testing efforts and exceptional documentation. Lou:
>> Functional requirements for power supplies? Bob Davis: Functional
>> requirements for structure and thermal performance? etc. etc.....we
>> have much to do, but I think worthwhile effort. By the way, I'm
>> reading (in a few spare minutes here and there) an EXCELLENT book on
>> requirements management. When I finish, look for a review of it on
>> my project management page. I will also be providing suggestions on
>> writing "good" requirements, based on that book and my recent
>> experiences in the day job.
> Yes, we have "top level requirements" for desired satellite functions,
> operating modes and parameters and link budgets. But again, I think
> we're sorely lacking in key "system" performance requirements based
> on real data - - - which can only be obtained by building and
> testing these key functions.
> I'm not a power supply guy, but I'll offer to assist in building and
> testing the circuits we need to characterize. Lou - point me in the
> right direction - tell me what you need!
> Regards...Bill - N6GHz
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