[amsat-bb] Crew packing Cygnus for departure (and launch of HuskySat)

[John Brier]

Thanks for all the history and information Jerry. It is very interesting
and I am sure others appreciate it as well.

It is funny you mention interference as that is one of the reasons I was a
little surprised the uplink is on VHF. I was told there was more
interference from things like cordless phones and taxis on 2 meters than
there is on UHF. Obviously it is more of a problem on a single channel FM
sat than a linear sat with room to move around.

Would love to hear more about why V/u was chosen.

73, John Brier KG4AKV

On Fri, Jan 31, 2020, 14:02 Jerry Buxton via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> On 1/30/2020 11:52, John Brier via AMSAT-BB wrote:
> > Can someone explain why V/u was chosen for the linear Fox (they are all
> Fox
> > right?) Over U/v that all the FM Foxes are?
> Hi John,
>
> While RadFxSat-2/Fox-1E is a Fox-1 series CubeSat in much of its design,
> it is also an "extra" Fox-1 in that only four Fox-1 were originally
> planned, the four FM birds.
>
> The intent to build a 5th Fox-1 was first determined in late summer
> 2014, when I was contacted by Columbus High School asking to partner
> with us as a STEM payload on a Fox-1 satellite.  After we determined
> feasibility they submitted a CSLI in November 2014.  Unfortunately,
> their CSLI was not selected in that round and they chose not to go for
> another (at least in 2015).
>
> The economics of ordering components in larger quantities basically
> created leftovers, especially PCBs, from the construction of the Fox-1
> FM birds.  Too, many of the components of the FM repeater had gone
> defunct in the years of design, development, and construction of the
> first four so another FM bird was not possible without a redesign of the
> RF system.  For Fox-1E, we faced choices in how to proceed with the RF
> system.  Drew had been suggesting a linear transponder, I took that to
> the team for consideration, and John Klingelhoeffer, WB4LNM, came up
> with the linear transponder design.  Originally intended to be U/v as
> the others, as things progressed and we wound up having "extra time"
> since the Columbus CSLI was not selected, it was subsequently determined
> that V/u was a better choice for this bird.
>
> The specifics of that choice of mode are best addressed by Drew as he
> was the protagonist on that choice.
>
> The choice was not arbitrary, there were user input and other
> considerations, and the link analysis worked.  I recall that urban RFI
> was a factor, my trip to Colombia back when (2013?) made 2m useful for
> about 30 degrees of the pass and it had to be above 60 degrees so I was
> familiar with 2m interference.  I worked Hector a lot, but things got
> pretty bad by the time a bird got to the U.S.  Signal quality was a
> reason as well, if I recall correctly.  UHF sounds better.
> I was in the midst of getting Fox-1A to launch so without searching for
> emails, beyond those I don't have any more worthwhile recollection.
>
> The decision to go with a linear transponder was driven by two simple
> facts:
> We needed to redesign the RF system, the (linear) reasoning was solid,
> and the Engineering team was capable and interested.
> There was enough member interest in a linear transponder to get a good ROI.
>
> Jerry Buxton, NØJY
>
>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
>