Building a Raspberry Pi magnetometer network

Source: Ciarán D. Beggan and Steve R. Marple

(Source: Southgate ARC)

Ciarán Beggan of the British Geological Survey describes how a network of 9 Raspberry Pi magnetometers were deployed to schools around the UK to measure geomagnetic storms

As computers such as the Raspberry Pi and geophysical sensors have become smaller and cheaper it is now possible to build a reasonably sensitive system which can detect and record the changes of the magnetic field caused by the Northern Lights (aurora).

Though not as accurate as a scientific level instrument, the Raspberry Pi magnetometer costs around 1/100th the price (about £180 at 2019 prices) for around 1/100th the accuracy (~1.5 nanoTesla). However, this is sufficient to make interesting scientific measurements.

During 2017, a network of 9 Raspberry Pi magnetometers were deployed to schools around the UK from Benbecula to Norwich. On September 8, 2017 a large geomagnetic storm was captured by the school magnetometers. Using these data and the array of other magnetometers around the North Sea, we were able to recreate the spatial and temporal changes of the magnetic field during the storm in great detail. The two phases of the storm show the westward (night time) and eastward (daytime) flow of the auroral electrojet currents in the ionosphere.

Source http://www.mist.ac.uk/nuggets

Download the paper Building a Raspberry Pi school magnetometer network in the UK
https://www.geosci-commun.net/1/25/2018/gc-1-25-2018.pdf

Click here to read at the Southgate ARC.

Spread the radio love

WRTH 2019: Now at Book Depository

Many thanks to SWLing Post contributor, Richard Langley, who writes:

WRTH 2019 is finally available from Book Depository — quite a bit later than last year.[…]

It’s up on their website today at $32.59 U.S. (26% off) with free shipping:

https://www.bookdepository.com/World-Radio-TV-Handbook-2019/9781999830014

Thanks for the tip, Richard! Book Depository is a great source. You can also check pricing at the publisher’ site, or from a distributor like Universal Radio (US), and Amazon.com (US). Book Depository’s price is hard to beat, though, especially for those living outside the US.

Click here to read our review of WRTH 2019.

Spread the radio love

Using bus service to ship heavy vintage radios

Many thanks to SWLing Post contributor, James Branch, who shares the following comment regarding the shipment of heavy vintage radios:

On the issue of shipping Boat Anchors, I’ve had good experiences using Greyhound Package Express, Tough-bin structural foam footlockers and proper padding.

The parcel is loaded at the bus station of origin and usually remains on that bus to its destination without having to survive a sorting center or multiple unhappy loading personnel.

It may be inconvenient to drop off and pick up at the bus terminal, but considering the irreplaceable nature of these rigs, it’s worth the effort.

http://www.shipgreyhound.com/e/pages/Home.aspx

I had no idea!  Thank you for the tip, James!

Spread the radio love

The NSA’s Software Defined Radio application “RedHawk” is now open source

Many thanks to SWLing Post contributor, Andrew, who writes:

Not kidding, a friend told me that NSA released a bunch of software to open source, the main list being here:

https://code.nsa.gov/

While looking at the list of projects on that page, halfway down the page, I found a project called “RedHawk” which is described as:

“A software-defined radio (SDR) framework designed to support the development, deployment, and management of real-time software radio applications.”

Now, being curious I opened the github link:

https://github.com/redhawksdr

[It] contains quite a number of subprojects, modules and other stuff, then I checked the main “RedHawk” project:

https://github.com/RedhawkSDR/redhawk

Here’s the documentation:

https://redhawksdr.github.io/Documentation/index.html

It seems really interesting; apparently it allows to define a wealth of processing stages (e.g. filters, converters…) and connect them to process signals coming from an SDR; I think it may be a very interesting and useful tool to fiddle/experiment with SDR receivers, if I’m not wrong it may allow to push an SDR to the limits, improving its performance, and may also be useful to write SDR software!

Fascinating! Thank you for the tip, Andrew!

Post Readers: It appears this project has been in the public domain for a little while. Please comment if you’ve tried implementing RedHawk in your SDR system!


Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

Your support makes articles like this one possible. Thank you!

Spread the radio love

Australia: International broadcasting, soft power and the wisdom of the crowd

Many thanks to SWLing Post contributor, Nigel Holmes, who writes:

Here are a couple of interesting url following the joint Australian DFAT & DCA Review of Broadcasting Services in the Asia Pacific. [One] gives a good overview and the [other] is a concise assessment of HF and Radio Australia in the role of broadcasting to remote areas. Have a look. Former RA Head Jean-Gabriel Manguy made a submission, I did not this time. The submissions are in the public domain.

Click here to read Trevor Bird’s submission (PDF).

Click here to read Jean-Gabriel Manguy’s submission (PDF).

(Source: Lowy Institute – The Interpreter by Geoff Heriot)

International broadcasting: the ABC vs the wisdom of the crowd

The findings of two related government reviews – on international broadcasting, and soft power – should offer an incoming Australian government the potential of a substantial policy reset following the general election in May. Specifically, they may help clarify the purpose and place of state-funded international broadcasting/digital media in Australia’s foreign relations, following a decades-long cycle of investment and dis-investment.

Shortly before Christmas, the Department of Communications published most of the 433 submissions (92 private individuals, 31 organisations or groups, and 310 signatories to a pro-forma submission) made to the first of those reviews, Australian Broadcasting Services in the Asia Pacific, excluding those whose authors wished them to remain confidential. Finalisation of the broadcasting report precedes the related Soft Power Review, being undertaken by the Department of Foreign Affairs and Trade, which has proposed a completion date of around March.

So it is timely to take note of the wisdom of the crowd, as expressed through the more discursive submissions to the broadcasting review, and to compare them with the institutional perspective of the ABC as the responsible agency for international broadcasting.[…]

Click here to read the full article.

Spread the radio love

Fast Radio Bursts (FRBs) from a distant galaxy detected

Many thanks to a number of SWLing Post contributors who’ve shared the following news:

(Source: Southgate ARC)

Mysterious radio signals from deep space detected

BBC News report astronomers have revealed details of mysterious signals emanating from a distant galaxy, picked up by a telescope in Canada.

The precise nature and origin of the blasts of radio waves is unknown.

Among the 13 fast radio bursts, known as FRBs, was a very unusual repeating signal, coming from the same source about 1.5 billion light years away.

Such an event has only been reported once before, by a different telescope.

“Knowing that there is another suggests that there could be more out there,” said Ingrid Stairs, an astrophysicist from the University of British Columbia (UBC).

“And with more repeaters and more sources available for study, we may be able to understand these cosmic puzzles – where they’re from and what causes them.”

The CHIME observatory, located in British Columbia’s Okanagan Valley, consists of four 100-metre-long, semi-cylindrical antennas, which scan the entire northern sky each day.

The telescope only got up and running last year, detecting 13 of the radio bursts almost immediately, including the repeater.

Read the full BBC News article
https://www.bbc.co.uk/news/science-environment-46811618

Spread the radio love

Finding a repair service for boat anchors and other vintage valve/tube radio gear

Vintage tube radios will likely survive an EMP, but how do you power them without mains electricity?

Here’s a common question I receive from SWLing Post readers:

“Where can I have my vintage valve/tube radio repaired? Can you recommend a good repair service?”

The answer isn’t always a simple one, especially for those living in rural or remote parts of the world.

Go local

The short answer is: try to find a local repair service.

Unlike modern solid state radios, “boat anchors” (metal chassis vintage radios) are heavy and very pricey to ship.

Some repair services and retailers won’t even consider shipping vintage metal chassis radios because of the likelihood of damage or a tube or other component loosening during transit resulting in a DOA (Dead On Arrival) situation. They insist on in-store or local pickup/delivery.

Johnson Viking Ranger transmitter

 

Last year at the Dayton Hamvention I was speaking with an acquaintance who restores and repairs vintage tube radios–he specializes in WWII and Cold War era boat anchors (Collins, Signal Corps, Hallicrafters, National HRO, etc.). Although he makes a tidy profit from doing repairs, it’s most certainly a labor of love and not the most profitable use of his time.  He told me that he recently stopped accepting any repairs other than those delivered and picked up locally.

He told me he took great care in packing equipment after repairs had been made–he’d secure all components so that they couldn’t budge during shipment and would either double box or use industrial strength cartons. Being so diligent, his return shipments almost always arrived unscathed, but customers would complain about the shipping costs. He could, of course, skimp on packaging, but then risk his repair work being undermined by rough handling. He was never willing to compromise on shipping and I certainly don’t blame him.

So again, due to the complexities of shipping heavy gear, I always recommend trying to find someone local to do your “boat anchor” repair work first.

Where can you find a local repair shop? If you belong to or know of a local ham radio club, stop by a meeting and ask around. If there’s a vintage radio repair technician in town, someone in the club can likely connect you.

Shipping boat anchors

With that said, there are some excellent repair technicians out there who will take work via parcel shipments, but be prepared to pay upwards of $50-150 each way each way (depending, of course on the radio size and weight).

Lighter tube radios are easier and cheaper to ship, but should still be packed carefully. Bakelite radios, for example, are lightweight but incredibly fragile.

In short: if you ship your vintage radio, pack meticulously and confirm that your repair person will do the same.

And where do you find repair services? I point readers to radio repair service reviews on eHam.net. You might also search the QRZ.com forums or even post a question.

Let’s be clear: some radios are worth the shipping costs!

I am fortunate in that I do have a local friend and mentor Charlie (W4MEC) who repairs tube gear. Better yet, Charlie is willing to teach me how to do repairs and alignments myself. This, I would argue, is the best of both worlds!

A Note of Caution: When it comes to repairing tube/valve gear, I believe you should always learn the ropes with an experienced technician. Unlike battery-powered solid state devices, tube gear is mostly high voltage. If you don’t know what you’re doing inside the chassis of a tube radio, you could be severely shocked or even electrocuted. No radio is worth that price.

Who do you recommend?

If you have any advice about repairing boat anchors and other vintage electronics, please comment! Also, if you can recommend a repair service, please share details.

Spread the radio love