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Re: [IRCA] [ultralightdx] Oregon Cliff (Rockwork 4) Ultralight DU's for 7-17...Wild!

--- Begin Message --- Thanks for the comments Nick. I have been happy with the Perseus for the more than 5 years I've had it. It allows me to do things that my previous SDR (the RFspace SDR-IQ) and conventional receivers did not.
After-the-fact two-antenna phasing would certainly be another big step forward. For me this would be more useful than capture bandwidths greater than 2 MHz, VHF/UHF capability, and various other performance upgrades.
There are still other tools that live DXing can provide such as the aforementioned web receiver / station stream parallel checking and (I suppose) chat-room / telephone collaboration with other DXers and broadcast engineers running DX tests.
The SDR playing field beyond Perseus is certainly getting interesting with current and anticipated models by Elad, Afedri, Excalibur, Software Radio Laboratories (QuickSilver), et al. I am wondering how many of these will be commercially viable in the long run, especially considering all the talk about the "death" (or, at least, slow demise) of radio. Shortwave radio in particular seems to be on a fast downhill ski slope.
Will the production of these innovative receivers peak at some point before too long and then start to decline? Food for thought I guess.
Anyway I'm happy to hear about all the Pacific Coast summertime DX activity by Gary, Chuck, and others. Chuck's captures are starting to make activities out there sound like a sort of "Newfie West", a situation where something great can be heard on the dial all year. Previously Grayland, Haida Gwaii, and other sites have certainly provided some great DX wideband capture files during the more-traditional autumn/winter stretch. And Gary has given us a lot of summer DX with the narrowband live-DXing approach. But Chuck's latest foray may be the first time serious summertime West Coast wideband captures with a Down Under focus have been realized. A big development for sure. This is the West Coast equivalent of late spring / summer Newfoundland DX sessions featuring Africa and South America more than the "usual boring" Europeans. I think a lot of us would like to have some of Chuck's better new files put up on Mediafire, Box, or some other large-files downloading site so we could "sit in front of the dials" ourselves. 

Mark Connelly, WA1ION
South Yarmouth, MA

<<
Thanks for your thoughtful analysis Mark.   I might add that the
advantage of live DXing of being able to phase antennas may also
becoming overtaken by technology.

The AFEDRI Dual Channel SDR (AFE822x SDR-Net)  allows diversity
reception (two SDRs set to the same center frequency and same
bandwidth, coherently synchronized), and those two channels may be
combined in software to be phased with each other, assuming each
channel is fed with a separate antenna.   The same thing could
presumably done with recordings after the fact.   The company
provides only hardware; they say that the software to do this
includes HDSDR + SDR_Control (SDR-Control is provided by Afedri),
PowerSDR_mrx and Linrad, though I have no personal experience with
any of this.    Someday...  (check
http://afedri-sdr.com/index.php/ordering-information for details)

The X2 option for RFSpace's NetSDR provides similar functionality,
but doesn't seem to be widely available.   I believe Gnuradio
supports it, but I don't know whether phasing the two channels is
addressed, or whether that will be the user's contribution to the
mix. Simon Brown is  (perhaps) working towards providing phasing
capability for the X2 in his SDR-Console, but he seems to have a lot
on his plate.

A very few radio stations now provide online audio archives of their
recent broadcasts, and I've ID'd Radio Sport from New Zealand as well
as Taiwan Fisheries broadcasts using this method and recorded SDR
files.   Now, THAT'S DXer friendly.

best wishes,

Nick



I am a firm believer in "both kinds of DX": live and after-the-fact
capture analysis.

Whenever possible you should use a mix of the old-school and
new-school methods.

Advantages of live DXing:
* You can use webstream, remote-receiver, and shortwave parallels.
* You can use high-Q tuned antennas rather than broadband.  In two
situations this is the way to go.  One would be when you have very
weak signal conditions and not enough space for a broadband antenna
of sufficient sensitivity.  The other would be when you are in an
urban situation where any broadband antenna of sufficient gain to
hear DX is going to present locals at such high levels that the
receiver will create spurious signals.
* You can use a phasing unit to target the specific "pest" affecting
the frequency on which you're actively DXing at the time.  It takes
a very good antenna system (e.g. physically-large array) to deliver
much better than a 25 dB null in a broadband sense.  But narrow
bandwidth nulls of better than 40 dB are easily had with a Quantum
Phaser (or similar) and a pair of different-pick-up antennas (e.g.
loop vs. whip, loops at right angle), or with two similar-pick-up
antennas spaced at least 50m / 164 ft. apart.

Advantage of after-the-fact capture analysis (Perseus, Excalibur, etc.)
* During a "hot" opening, a single top-of-hour capture gets you a
whole medium-wave band worth of ID's.  This would take much more
time to accomplish with live DX sessions.  Optimum conditions may
have gone away by the time you're even halfway through the band
doing it live.
At US/Canada East Coast beach sites around local sunset, two
top-of-hour captures (+/- 3 min.) can get you an amazing amount of
choice DX.  Same is true for West Coast around local dawn.  And, if
it's auroral, admittedly a fairly rare occurrence in recent years,
you'll be busy all night on tops-of-hour as well as on the
half-hours for the Venezuelans.
* You can repeatedly replay a given target, trying AM, synchro AM,
USB, and LSB modes; various IF bandwidths; notch filters et al.  On
live DXing you have less time to figure out the optimum receiver 
settings.


Since you typically won't have webstreams and shortwave to assist
you on after-the-fact analysis of medium wave capture files, use the
periods BETWEEN the tops-of-hour (:00+/-3) and bottoms-of-hour
(:30+/-2) captures to do live DX, making sure to avail yourself of
things that are only feasible when DXing the old-school way.  You
can still have TotalRecorder (or your other favorite audio recording
tool) running during the live DX activity since you won't want proof
of a breathtakingly rare catch passing you by.  What you find out
during the between-captures live DX will feed into antenna-aiming
etc. decisions you may want to make before the next capture session.

--- End Message ---
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