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[IRCA] Backpack DXpeditioning (was: Elad FDM-S2 initial testing)

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 Chuck mentioned more modern Atom-based netbooks that can run Perseus captures at full MW bandwidth successfully.

Presumably there's something out there in a small form factor (under 14 inch screen) that can run full >= 1200 kHz width Elad captures also.  Any info on these will be appreciated.

Tablet with separate keyboard seems like a clunky option since, even though it's two small pieces, it's still two pieces instead of one.  More things to lose, drop, break, get wet etc. out in "the bush."  Touch screen character entry is another possibility (as tablet and smartphone users well know) but do you really want the pop-up on-screen keyboard covering part / most of the receiver graphical interface window you need to see?  Add in factors such as glare, rain, snow, blowing sand / salt, space constraints, adverse temperature conditions, possible need for gloves - maybe a sensitive touch screen device isn't what really you'd want.

My opinion is that if a powerful enough traditional netbook size PC isn't available, I'd still stick with a regular laptop even though the size is larger.

Packing a second charged-up laptop battery isn't a bad idea.

Regarding antennas, some shore sites around here don't have any significant supports.  Rocks and/or sand right near water's edge, beach grass / goldenrod / low shrubs (rugosa rose, bayberry, etc.) right behind that.  Larger shrubs and small trees (beach plum, red cedar, pitch pine) might be found about 100 ft. back.  Often these are not particularly straight or tall because of constant blasting by salt and sand laden winds.

So it's likely that a single collapsible fiberglass or similar non-metallic pole of at least 3m / 10 ft. needs to come along to support the apex of a Delta (triangular) shaped loop.  Tent stakes with bungee cords can be used to tension the ends.  Kaz antenna 10-12 ft. high by 35-40 ft. wide gets you in the game if you provide some amplification (Wellbrook, Lankford, Kiwa, DXE RPA-1, W7IUV, etc.) between the antenna feedpoint and the receiver.

The delta shaped loop can be configured as a bidirectional (figure-of-8) antenna instead of a terminated cardioid one if that suits the situation better.

Anchoring the support pole can be a non-trivial matter, especially in the type of winds found at desirable seashore or mountaintop sites.  Rocky or sandy ground instead of sod doesn't help.  A patio umbrella stand certainly works but those puppies are usually at least 10 kg / 22 lb.  How far would you want to hike with that?  Guy ropes and tent stakes might be easier.  Still, if winds are high, you may be limited to wires on the ground.

Vehicular-based DXpeditioning is an easier proposition.  The 2m x 2m car roof loop has worked well for me on beach DXpeditions for many years.

http://www.qsl.net/wa1ion/loop/car_roof_loop.htm

Mark Connelly, WA1ION
South Yarmouth, MA
 

-----Original Message-----
From: Nick Hall-Patch <nhp@xxxxxxxx>
To: Mark Connelly <markwa1ion@xxxxxxx>; irca <irca@xxxxxxxxxxxxxxxx>
Sent: Wed, Mar 8, 2017 9:34 pm
Subject: Re: [IRCA] Elad FDM-S2 initial testing


Thanks for the further observations Mark.    I've traveledin the past with an ALA100 and a chunk of wire, and almost always beenable to find a support of some sort.  One of the many advantages ofa loop is the ability to place it close to the ground, and the ALA100 isquite resistant to noise from the feed line.   #22 wire andRG-174 feed line is light.

Hasn't the old style inexpensive netbook pretty much died out now? (ones with RJ45 that can be used with Afedri or NetSDR / Cloud-IQ, pluslargish hard drives, effectively a small laptop)  One I had was ableto handle 1300kHz bandwidth NetSDR recording with ease, but we weretalking about Elads, which would be much preferable for travel, and theElad struggled on that machine.

There are several inexpensive tablets that have an accompanying keyboardwith USB ports, but although the one I have is quite zippy, there isn'tmuch native storage for SDR files.   As I live in Canada, Irealize that I may not be aware of all the options, and don't keep up todate very well anyway.    Maybe Guy Atkins has somethoughts?

best wishes,

Nick

===

Mark -

It's bad science to quote the 9 year old MSI Wind with its first generation Atom as an example of netbook/Perseus issues.

Semi-modern Atom processors are 3 to 4 times faster than the primitive N270 used in the Wind.

I have no problems running Perseus on the ubiquitous Z3735F tablets and netbooks that are available for under $100. Just don't expect to surf the web, make a spreadsheet, read a pdf file or Skype at the same time.

Chuck
________________________________
From: Mark Connelly <markwa1ion@xxxxxxx>
Sent: Wednesday, March 8, 2017 9:05 AM
To: nhp@xxxxxxxx; irca@xxxxxxxxxxxxxxxx
Subject: Re: [IRCA] Elad FDM-S2 initial testing

With the Perseus I had a similar experience. Atom-based netbook (MSI Wind) gave me OK record / playback up to 800 kHz bandwidth but it couldn't cut the mustard for 1600 kHz wide captures. Core i3 or higher: no problem.

Are DXers using any netbook form-factor PC's (screen 10 to 13 inch range) that have i3 or better CPU's? Seems like that's what you'd really want for backpacking. Battery life in excess of 4 hours (including the receiver's loading) would be a plus.

Of course you still have to deal with getting an antenna out there, hopefully a directional one. Roll of skinny wire to stretch on the ground + a matching / isolation transformer might work but grounding still has to come into play. Directivity would be sketchy at best. A wire loop is likely better (whether cardioid or figure-of-8 pick-up). The support structure for that (when trees are lacking) is going to be a bigger impediment to backpacking than the laptop + SDR combo. Tuned loops, of course, can be quite compact but then you're essentially limited to one frequency at a time (live) DXing instead of wideband capture for later analysis. Active whips are also compact but they can be "noise getters" if placed within 20 ft. or so of the laptop. No directivity with those either, although a shore site produces directivity independent of the antenna. Single stick pattern of my 1240 local demonstrates that:
http://radio-locator.com/cgi-bin/patg?id=WBAS-AM&h=D

(That map shows why Florida, Cuba, Puerto Rico, Venezuela, etc. bomb in here ... Midwest not so much.)

I would always take a competent ultralight portable in the backpack as well, just in case something with the PC + SDR goes "kerflooey." No sense to go out there and come back with nothing, especially if considerable flying, driving, biking, or hiking was involved.

Mark Connelly, WA1ION
South Yarmouth, MA

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