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 â??DXâ??
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-5â??s
> 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 â??repeat
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 donâ??t 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, thatâ??s 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 weâ??ve missed anything in our planning.
> Nick and I are both â??elderlyâ?? and we want
to get this eclipse right so we
> donâ??t have to wait for the next one.
> Cheers!
> Mark Durenberger, mobile
> _______________________________________________
> IRCA mailing list
> IRCA@xxxxxxxxxxxxxxxx
> http://montreal.kotalampi.com/mailman/listinfo/irca
> Opinions expressed in messages on this mailing list are those of the
> original contributors and do not necessarily reflect the opinion of the
> IRCA, its editors, publishing staff, or officers
> For more information: http://www.ircaonline.org
> To Post a message: irca@xxxxxxxxxxxxxxxx
_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca
Opinions expressed in messages on this mailing
list are those of the original contributors and
do not necessarily reflect the opinion of the
IRCA, its editors, publishing staff, or officers
For more information: http://www.ircaonline.org
To Post a message: irca@xxxxxxxxxxxxxxxx