Radio Technology

Field Day

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My first ham Field Day was 46 years ago, and today a few of us continued the tradition at Portola Valley Town Center admittedly with some adjustments for comfort. It’s THE national contest that simulates emergency field radio operation and no it just doesn’t get much nerdier. One year I continuously operated so much high-speed Morse Code, that as I drove away, each rattle and bump became a random letter.

I owe radio a lot. Nothing quite like the confidence it gives you to (in 1970) build an 2000W RF amp from a 3-page article and see it pump out 4000W because of your power supply improvisation. Abundant challenges and opportunities continue from the contributions of a hugely talented and diverse international pool. We are at the forefront of ad-hoc mesh networks. We have complete radio-based mail and file sharing with gateways. We have satellites that refresh messages and location information, weather; even the ISS is linked in.

To see the progression from repurposing WWII surplus gear to having my own satellite tracking system has been astonishing and a privilege, with which I hope especially my gear-head friends can sympathize.

Thanks to Chris Raanes, Ray Rothrock, Steve Golberg, Dale Pfau and Stuart Young for a great meet.

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WSPR at Low Cost

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Everyone talks about propagation, but nobody does anything about it! That’s of course because it is completely out of our control, and to degrees arguable by experts, notoriously unpredictable. Many institutions are devoted to Space Weather and tasked with forecasting ionospheric conditions. But I’ve never found a month- or week-old sunspot count of use on the occasion I care to operate. One can check the generous number of real-time solar parameter reports, but these at least need prerequisite expertise, and at best are not unequivocal.

What is unequivocal is what is actually happening, and you can find this out by observing and participating in the Weak Signal Propagation Reporting network, in which amateur stations systematically probe current conditions using synchronized digital coding at very low power throughout the LF and HF spectrum. WSPR offers a fascinating, informative real-time window into your most likely communication opportunities. [http://wsprnet.org/drupal/]

Two recent offerings offer low-cost entry and eliminate the need to commit a full rig to 20M or 30M WSPR operation. First, the RW-1 receiver. I knew my location was not good but thse results were disappointing. No doubt the bare-wire quasi-inddor antenna here is a limitation to be revisited. Neither am I convinced the PC audio input was behaving.

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Next, the WSPR-AXE transmitter from W5OLF. Here the point needs be emphasized that this is a Class E transmitter which really requires a good match to its expected 52 ohms. Thus, through a Drake MN-2700 which allowed peaking full 1W output into a DX88 vertical, the results were great; topping the evening with a bounce back to the East Coast to K1JT, Joe Taylor, inventor of the WSPR system (and other protocols).
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2013-02-04 at 6.19.05 PM K1 JT!
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Now familiarized, to obtain multi-band coverage, this does look like a perfect task for the obligatory spare IC-706. The WSPR lunchbox then travels with the HF mobile system, to confirm efficient QTHs.

We Did It! Portola Valley Field Day

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Revised: 20120711

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Chris Raanes W6CAR, Ray Rothrock WB5NVN, Steve Goldberg WQ6L & me.
Notable visitors ARRL SCV Section Manager Phil Steffora K6TT, and Brandon Bianchi NI6C—New SCV Section Manager (Starting July 1) pitched in; Councilman (ret) Steve Toben.

Notice that the perfect weather and abundant food forced us to work in obviously dire emergency conditions.

More seriously, this exercise exhibits intrinsic merit of a deep tradition for testing rapid deployment and evolving versatility. In fact, the ionosphere was not particularly kind this day, limiting the distance of confirmable HF (1.8-30 MHz) contacts and causing considerable re-strategizing. Ironically, this HF vulnerability to the “Maximum Usable Frequency” simultaneously highlighted the need and role of satellites; which have their own limitations, but do not depend on ionospheric bounce.

My previous field day may have been 40 years ago: and I had to ponder what my mentors might think of now portably tracking satellites while operating indefinitely from solar power. In the 60/70s we paid scant attention to the satellite fringe. Now, with cubesats reportedly available for $10K, the relevance and role of private satellites renders yet another dramatic communications breakthrough and opportunity.

Deep thanks to my buddy Bill van Erp for help with the substantial logisitics needed to actually move my system: It could not have happened otherwise. He also took most of the photos.

An Inadvertent Turn

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Everything seemed to be going fine.
Crusher had started the Honda EU2000 generator with a couple of pulls no problem.
But then, it would mysteriously stop.
Seemingly after connecting a load. Or not?
Then it got real ornery, not even a pop or a kick.

Vinnie couldn’t work from all the swearing and cussing;
went outside: “?Sup Crusher?”
“Aw boss you know this thing never gave us a problem,
now I pulled my damn arm out of my socket for the past half hour
trying to get it to crank. I checked the oil, plug.”
Crusher?
Yeah, Vinnie?
Check out out the gas fill cap.”

Crusher looked crestfallen; but then it didn’t take him long to spot the otherwise invisible, concentric molded black-on-black gas ON/OFF lever of which only the truly initiated would know; hence not be as fools at the mercy of an undetected flick.

Crusher’s monstrous unmanageable mitts were indeed able to find the inscrutable, unexpected lever to enable the flow of gasoline. The EU turned over with a couple of pops.
“Gee, I guess it accidentally got switched off, huh? Like maybe when I moved it?
You know, Vinnie, I’m SURE I read the manual. And I was wondering about that. No lever under the covers. How do you put the flow control up near the fill inlet anyway? It’s always on the tank outlet.”

“I know Crush, I know … It’s consumer, dude; for someone who hasn’t seen an open frame system. For those who have, it is just another little paradigm shift.

Forget about it. Rest those arms.”

EmComm Trailer for Field Day Sports New Twist

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Revised 20120524

Playing hardball this year: To the proven setup of GlenMartin RT-424 tower and Yaesu thrust bearing GS-065 holding Yaesu G-5500 split-rotator array of ten-foot M2 satellite beams 2MCP14 and 436CP30 with SSB SB-2000/7000 preamps, is added a Comet H-422 for directional coverage from 40M-10M. Comet assembly was a dream and SWR is under 2:1 throughout. The preamps are powered by the trailer’s battery array, and their voltage is reported down a spare rotator cable line to a dedicated voltmeter at the station. Not visible, an Icom AH-4 exploits a bare wire for 80-6M for virtually any Icom transceiver. The trailer thus simultaneously supports three separate transceivers virtually “DC-to light.” As the tower is hinged, the entire structure can be assembled entirely safely from the ground by one person.

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The TS-2000 has remarkable versatility and depth. The diagrams describe the back-stage area for this first minimum phase. It takes several (TBD) high-current diodes to get the RigRunner consistently low enough below the AGM charger to not trigger its audible Over-voltage alert.

Next is to verify ac-line independence (generator), then adding solar power charging, and high-power inverting. The limiting factors here are the EMI electrical noise from very many of these devices; dictating a search for effective outdoor shielding material and technique.

Jameco Re-Purposes ‘Cognitive Radio’ Article

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It was fun working with editor Frances Reed to address her diverse newsletter audience. My Story: Cognitive Radio

A comparison to the original (Cognitive Radio is Here) shows her having set a broader context, while simultaneously pulling out from me the three figures for more detail.

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Since that story there has been a further important, related development for Software-Defined Radio (SDR), which I discuss here:

Bid, Baby, Bid! Software-Defined Radio Poised To Gush!

Bid, Baby, Bid! Software-Defined Radio Poised To Gush!

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The issue of the Payroll Tax Compromise is quite beyond pretense of my understanding though I do well understand the resource largely tapped to pay for it: so-called “white space,” that is, unused frequencies in the over-allocatted TV spectrum.

I have before praised Rep. Greg Walden as an active critic of the FCC and Chairman Genachowski—that agency having been lost in the woods on issues of white space and Emergency Interoperability (among very many others). Walden has investigated the FCC and recently offered reforming legislation. But now, as House co-sponsor of the Payroll Tax bill Walden has in one stroke solved two key issues the FCC has fumbled for a decade, and deserves hearty congratulations therefore.

Walden Statement on Job Creating Spectrum Provision in Payroll Tax Conference Report – YouTube

Having spoken with Walden’s well-qualified Communications staff, I am confident they deserve specific credit for the emergency interoperability provisions, and am encouraged that they may re-visit the dubious P25 technology, hopefully leapfrogging it. (And as a cherry on top, in-filling the TV spectrum uses wavelengths that are far less controversial as unhealthy.)

You are rightly picturing many of the required new jobs building infrastructure: laying fiber, building servers and transceivers. But you might not yet realize that in truth none of this will happen without inventors and investors deploying legions of radio engineers to realize the required entirely new architectures for software-defined radios (SDR) that are agile enough to exploit the new spectrum. The challenge and opportunity for SDR is now, precisely as we are graduating programmers newly familiarized with these techniques!

That in this political environment Congress reached this compromise is certainly significant. Walden is right: It is now up to technologists to respond to the government’s lead, sharpening their management and engineering drills to ensure that electronic commerce continues to cause bandwidth to gain value against crude oil.

DC over AC Using 3-Wire PowerPoles

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Use this idea to move that noisy power supply away. Or use the Male connector to energize a switched-off house branch with 12V. Obey current limits and create at your own risk.

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