Portable Operations #2 – Field Weekend T-1 and counting

OK, we are now officially 15 hours away from FPARC’s July Field Weekend and the excitement is bubbling!

Not wishing to look a prize buffoon by rocking up with lots of stuff and finding it doesn’t work, I thought it prudent to actually see if my portable concept worked in the relative safety of the back garden. So, duly equipped with a pair of shorts and Oakley Half Jackets I gingerly transferred my rig to the patio table and started working out what I was going to take with me.
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After considerable wrestling with the drivers for my rig-cat cable, reminiscent of my post Rig Cat Problems #3 and forgetting how to use my Elecraft T1 ATU, we finally got there! The next trick was to get this stuff packed down into a portable package.

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Now this is a bit of a cheat as originally I was going to build a manpack based around M0PZT’s Porta-Frame which is a very cool idea.

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The however comes in that when I priced up all the copper fittings, tubing, brazing torch, solder and flux I’d need to build one, it came in at about £4 cheaper than the FT-817/857 backpack I found on eBay. Don’t get me wrong I was all geared up to build one but here’s the thing. Expensive electrical items, by their very nature don’t take too kindly to moisture and being the UK, we have plenty of that. Just ask your 52″ LCD TV how it feels about standing out in the Great British weather for half an hour and I think you’ll get the idea. The backpack is fold and go, so when the heavens open, we’ve got some immediate protection. Also, the fact it has a ground sheet layer built into it means you can unfold and work without having to worry overly about the dampness of the ground. Everything folds down very cleverly and buckles tight. The storage pockets for cables and bits are a bonus and the rucksack straps make it instantly portable.

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As this my first road trip, like any adventure, it’s worth overpacking! With a few elements of redundancy along for the ride my entire portable setup, minus my field mast, is packed in three small bags – an Aldi bag for life, a Bomber Barrel grip (best damn grip in the world!) and my FT-817/857 backpack.

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All I need now is my BBQ contribution and we’re there!

 

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Portable Operations #1 – Field mast

The objective for 2016 is to get out of the shack and into the wild with a radio. This has been on the agenda since day one, but like every idea there are teething problems, interuptions and cost implications!

That said we took one step closer today when I finalised my antenna mounting platform for use at field day events. This is a two pronged attack, giving me a mast I can mount an HF antenna on along with my BBHN node, which will give me Mesh access for WX, Cluster reporting and logging. While I mention WX have a look at this – blitzortung.org. It’s always useful to know how far away the serious trouble is!

So, on a bright and cheery Sunday morning I took a little trip to Fort Purbrook to see if my latest creation actually worked as it was based on a sketch and dimensions I was gifted and unfortunately I wasn’t able to actually get a hands on, prebuild examination of the trig point to get things straight in my head before I started hacking up my very limited supply of free plywood. Added to that, I have the woodworking finesse of dry rot, so the margin for error was slimmer than the shrinking exchange rate value of the pound!

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In the words of Shrek, “That’ll do Donkey, that’ll do!”

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When it drys out from the soaking with drizzle this morning I’ll give it a quick once over with yacht varnish to stop mould and the like setting in while in storage. The whole kit breaks down very nicely to a light weight bundle for transporting.

101 uses for a DVB-T dongle

I only got into Amatuer Radio proper in 2014 as a byproduct of something else I was playing with at the time. Some kit I was looking to buy carried the caveat of “may require an Amatuer Radio licence to operate on certain frequencies” and not wishing to end up on the wrong end of some draconian individual I decided to sort the licence side out first before shelling out my hard earned on my new toys. Somewhat naively I assumed obtaining a licence to operate radio equipment was similar to obtaining a licence to fish in common waterways. You know? Rock up at the local council office, flash your cash and walk away with a small square of paper saying you’re hot to trot. How wrong can you be?

Two years on and I’m slightly more educated and definitely finding radio more rewarding than previous ventures. Now when I landed in the world of the Foundation Licence learning it all seemed a bit abstract. I’m very much a learner by application rather than just being able to read and comprehend, so I wanted/needed a very cheap setup to play with to cement the theory. I wasn’t planning on being in radio land for very long (originally) so the cheapest way to do this seemed more appealing than ever.

I had a dabble with WebSDR to start with, especially Hack Green. Lets face it anything that says it’s based at the site of a previous secret nuclear bunker is going to draw the crowds! From there I fell for the idea of software defined radio and started reading, stumbling across RTL-SDR. What a resource that site is! Now I loved the idea of actually having a tangible SDR radio for the princely sum of 10 quid and invested.

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Meet my first radio! So after working out how to use it and listening to the limited range of content, mostly commercial wideband FM broadcast stations I needed something slightly more challenging to have a play with.

RTL-SDR offers a whole host of projects for the humble DVB-T stick and the whole idea of ADS-B radar fired my imagination. Living on the south coast with a host of commercial and private airfields in the county, plus a multitude of shipping traffic bobbing past in the Solent, this whole thing definitely had legs.

Next thing you know I was making antennas for the sole purpose of receiving aircraft ADS-B beacon transmissions.

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This is my massively successful quarter wave ground plane antenna built using the guide at ATOUK’s site. A copy is attached here for easy reference

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Bearing in mind I didn’t have a Scooby what I was doing I was gob smacked by the increase in reception of my little receiver when compared to the supplied stock antenna. I was on a mission from then on! I took myself off to Nevada and bought myself some lengths of coax and spent some time fashioning various collinear coax and wire antennas and testing them using various software tools to plot their reception characteristics. Nothing I made beat the tiny quarter wave ground plane, it reigns supreme to this day in the ADS-B stakes! Unfortunately I don’t have any of my original work to share with you as I dumped it when I upgraded my PC, but it was good fun.

From there I added a Raspberry Pi to the equation to make a dedicated ADS-B server

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followed by an ADS-B SAW filter to improve reception. I scoured eBay for the EPCOS 1090 MHz SMD device and fashioned myself a PCB.

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Again, the improvement in reception was dramatic.

Next came the addition of a LN4ALL low noise amplifier

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And all this to watch aircraft on a PC screen in a manner similar to an air traffic controller!

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It’s a project I really need to resurrect when I get 5 minutes.

Since then my trusty RTL-SDR dongle has found itself playing a key role in a few side projects alongside other SDR and conventional radios. It’s a piece of kit everyone should own in my opinion!

So how about turning your phone into an SDR radio? SDRTouch for Android does just that. There are apps such as glSDR which give you WebSDR, but if you’re not on WiFi or 4G it’s a bit limited. SDRTouch takes your phone and allows you to plug your RTL-SDR dongle into it and gives you your own portable SDR receiver for the cost of 99p for the OTG cable from eBay.

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And proof that it’s not just a fancy screen saver –

SDRTouch RTL-SDR test