Re: [IRCA] TWO DX-ERS AND THE ECLIPSE

[Neil Kazaross <neilkaz58@xxxxxxxxx>]

No joke here, Walt. Mark got a really great deal on surplus CAT 5 in bulk
and I've spent three weeks doing almost nothing but modelling the setup in
EZNEC.  73 KAZ

On Sat, Jul 15, 2017 at 3:13 PM, Volodya S <canswl@xxxxxxxxx> wrote:

> Surely this is a joke.  it's not even April.  A 2k km CAT 5 line between
> your SDRs, and it's a mighty large Terabyte storage you have!   ;-)   Walt
>
> On Sat, Jul 15, 2017 at 12:02 PM, Mark Mobile <Mark4@xxxxxxxxxxxxxxx>
> wrote:
>
> > There's been a lot of chatter in the Ham newsletters and the scientific
> > community about RF-signal measurements during the August 21st eclipse.
> But
> > not much has appeared in the âDXâ newsletters.  In the hope of
> stimulating
> > an exchange about proposed listening methodologies, we want to share the
> > eclipse-monitoring plan of two DX-ers...Nick Hall-Patch and myself.
> >
> > We plan to take advantage of a technology that wasn't available during
> the
> > last major eclipse: the Software-Defined Radio (SDR).  To give all
> signals
> > an equal chance, the Medium-Wave antennas used will be high-gain
> > omni-directional.  The SDR listening posts at Nick's Victoria British
> > Columbia home and my cabin in North-Central Minnesota will be connected
> by
> > a balanced wire-pair, with the separated antennas forming a
> > Very-Long-Baseline Eclipse-Catcher Array ("VLBECA").  RF measurements
> will
> > be taken from 9.01 kHz through 66.666 MHz in 1.1-Hz increments.
> >
> > For connectivity between us to form the VLBECA, we will use pair 3
> > (green/white) of special Cat-5 cable with pink jacketing.  (From our
> recent
> > desert DXPedition we found the pink outer jacket to be the best color for
> > optimal velocity factor in the Cat-5, and we were already aware that an
> > odd-numbered pair would maintain better polarity.)
> >
> > The exact distance between our two locations is 1,359.37 miles (or
> > 2187.69395328 kilometers if you're Canadian).  Since there are a lot less
> > miles than kilometers along the VLBECA, we chose to save money by buying
> > the connecting cable by the mile rather than the kilometer, and that
> meant
> > purchasing our Cat-5 in the United States.
> >
> > Further input on velocity factor from the National Bureau of Standards
> > (NBS) led us to choose stranded rather than solid wire for the Cat-5.
> This
> > created some contention between Nick and myself, since stranded copper is
> > more expensive.  However, when we realized the Cat-5 route took us
> through
> > the Bakken Oil Fields of North Dakota, we knew the superior mechanical
> > performance of stranded wire would provide additional integrity against
> > rough handling.
> >
> > For Cat-5 pair 3 termination consistency on the two ends, we asked for
> > bids for a pair of 2.2:1 matching transformers that would match the
> Cat-5âs
> > native 110-ohm impedance to the 50-ohm input of the 273 dB-gain RF
> > amplifier.  However no one could meet our specifications.  So we ended up
> > using the Western Electric 111C ârepeat coilâ since this device is known
> to
> > significantly reduce Group Delay https://www.jmu.edu/wmra-eng/
> > archive/repeatcoil.pdf
> >
> > To guard against inaccuracies in the eclipse schedule, we agreed to begin
> > recording at both monitoring stations at 0301 UTC July 27th, and to
> > conclude at 1921 UTC, September 31st.  For the SDRs, 5600 Terabyte
> storage
> > devices were acquired from Best Buy.
> >
> > Since we will be measuring signals expected to be at the very limits of
> > receiver noise performance, we spent a good deal of time thinking about
> > continuous battery power since, because of possible eclipse-schedule
> > inaccuracies, we donât want to stop the recordings during the above
> period,
> > lest we miss something.  Fortunately we were able to negotiate access to
> > the battery rooms of the phone companies at our respective locations.
> For
> > Nick, thatâs BC Telus (formerly BC Tel; formerly the Victoria & Esquimalt
> > Telephone Company and the New Westminster & Burrard Inlet Telephone
> > Company) and, for me, the Upsala MN Telephone Company (formerly the
> Upsala
> > MN Telephone Company).  Connectivity to these battery rooms will use
> > fabric-covered lamp cord acquired from Mark Connelly.  We believe the
> color
> > of the lamp cord fabric will not impact the Group Delay.
> >
> > Once the recordings have been made (assuming there really IS an eclipse)
> > Nick and I will meet in Salt Lake City Saturday October 7th late afteroon
> > to review all the recordings, and we plan to publish our results here and
> > in QEX on Sunday October 8th.
> >
> > Please let us know if you think weâve missed anything in our planning.
> > Nick and I are both âelderlyâ and we want to get this eclipse right so we
> > donât have to wait for the next one.
> >
> >
> > Cheers!
> >
> > Mark Durenberger, mobile
> >
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