Saturday, December 04, 2021

Why is every state's daily COVID report different?

We're not a big country really. It seems odd that each state has evolved a daily COVID report that broadly looks similar but has the various statistics in different orders.

I favour the South Australian approach which focusses on hospital patients and deaths.

Tuesday, November 16, 2021

I'm a panelist on ABC's Download This Show

Once again I was a guest on ABC RN's Download This Show presented by hard working and talented Marc Fennel.

"The Commonwealth Bank is adding cryptocurrencies to its banking app, becoming the first Australian bank to offer such a service.

Plus, Twitter launched its new subscription product, Twitter Blue, in the US this week but some experts are asking why some simple features are hiding behind the paywall.

And the US Justice Department is suing Uber over allegations it has been overcharging disabled people".

In the old days we used to go to an ABC studio to record shows like this. These days we're all remote. I've been working on improving my audio and the latest addition is a pop filter which lets me get closer to the mic without popping and I think my sound is comparable with Marc in the studio.

Listen on 300 big power AM stations on Thursday at 11:05 or you can listen on line here or via podcast.

Friday, November 12, 2021

Programming a Yaesu VX-6 with Chirp

I've moved to Melbourne, Victoria, and my 2m hand held radio didn't have any of the local frequencies in it. It's a real grind to program memories through the keyboard and, while I'd done a few, I'd also made mistakes along the way.

A serial cable was purchased from AliExpress and this morning I got it going.

The cable came with some software on a mini CD ROM but I don't have a way to read those so the next step was to get Chirp. I tried it on macOS, Linux and finally Windows, before the UI told me what I needed to do to get started..

Turns out, with a VX-6, you need to hold the F/W button down during power on and then press BAND to start the upload from radio to Chirp. (Those instructions weren't visible on macOS or Linux for some reason).

In the end, I threw away my own memories and grabbed the Chirp CSV file from the WIA which has all of the repeaters in it, with names showing the call signs. Great stuff WIA!

Uploading to the radio is similar, power on with F/W but then push V/M to start download. It took a few attempts to get all this to work, it seems timing sensitive.

Anyhow, now my radio is filled with repeaters and I was very happy to find that I could trigger the Macedon repeater, VK3RMM, from home for the first time. (Clearly I had something wrong with my manual configuration).

Note that the CSV file from the WIA which could be imported by Chirp was from the file titled "Example VBScript, Sorted Directory csv and CHIRP csv files and other csv formats WiaRep2" from this page.

My sincere thanks to whoever put this file together.

Sunday, October 31, 2021

Response to attacks on the ABC by the Institute of Public Affairs

Last Monday the IPA published the first of five episodes in a new podcast series, “Their ABC”. Its preposterous proposition is that the ABC – in the words of the podcast’s anchor, the IPA’s Director of Communications, Evan Mulholland – is “a bloated, out-of-touch, biased broadcaster”.

The ABC Alumni, of which I'm a member, has published a video taking on the IPA’s “research”. It’s presented by our chair Jonathan Holmes, former presenter of the ABC’s Media Watch.

I realise that responding like this invites the Streisand effect but I think it's worth countering their misleading statements. 

Saturday, October 23, 2021

Surface mount on home drawn circuit board

I've been slow to adopt surface mount components for home construction but watching Paul, VK3HN's, technique has convinced me it's the way to go. The way he lays components on a board, draws the tracks with a pen, then simply solders components on to the surface seems particularly elegant.

As a test I've built a simple emitter follower audio stage with a 3904 small signal NPN transistor. The transistor is tiny but able to be soldered. I've used a normal Sharpie pen in the past but recently picked up some Staedtler permanent markers which are often recommended. Here's the resist and you can see the transistor top right:

I etch with ferric chloride in a small plastic container.

This small amount has done a few boards already. It would last longer if I coloured in more of the copper area. Paul tells me that warming the solution will keep it going even longer if desired.

This board wasn't great but worked well enough to solder components in place.

A wonderful benefit of surface mount components is that you can buy these books containing all common values for not much money. I bought the large 1206 sized components to make it easier for me to work with them. It's great to have plenty of every value resistor and capacitor at hand in a compact book. The result, on my first attempt, is a bit rough:

Working with surface mount is not hard if you have good light, a magnified headset, tweezers, and something to hold down the part while you solder the first connection to a component.

Tuesday, October 12, 2021

On ABC RN's Download This Show

This week I'm a guest on Marc Fennell's ABC RN "Download This Show".

"We’ll soon be walking around with them and flashing them to wine, dine and travel – but how easy will it be to spot a legitimate vaccine passport compared to a fake one? We discuss what could have prevented a security flaw and what’s being done about fake vaccine passports.  

Meanwhile, the Commonwealth Bank of Australia will be using an artificial intelligence tool to stem abusive messages being sent on electronic payments.

Plus, Facebook and Instagram introduce new features in an effort to protect young users from harmful content.

And would you wear a smart headband that claims to make you calmer?"

Marc was in the studio, I'm at home using an Audio-Technica USB microphone and I think it sounds as good as the studio.

uSDX tiny multi-band transceiver

The uSDX is not a great receiver or transmitter but it is usable and amazingly small. I bought mine through AliExpress. "uSDR uSDX 10/15/17/20/30/40/60/80m 8 Band SDR All Mode HF SSB QRP Transceiver Compatible with uSDX QCX-SSB".

Here's a recording of how a fairly week signal on 40m sounds:

The first unit I bought arrived with a broken screen. The AliExpress vendor provided free shipping for the return and refunded my payment.

I previously built the same circuit but this fully built version is more compact.

Manuel, DL2MAN who is the original designer of the uSDX sandwich contacted me with some comments about this (and similar) clone of his design. He has a video commentary and makes the following points:

  • His design is used but there is no credit to him at all
  • The license on the design was for non-commercial use only
  • He was never asked about a commercial license
  • The selling price is way above the actual cost (he thinks it would cost about US$40-$50) particularly as they are not supporting the developer
  • No effort was made with documentation, they've added no value for their margin
  • There are some changes to the schematic:
    • Output transistors have been changed but other parts of the circuit have not been adjusted
    • Harmonic suppression will be worse than the original design (and way below legal requirements)
    • Firmware upgrading is not easy as it was in the original design
    • The battery charging circuit is noisy
  • A physical design problem can short circuit the battery in the version with a battery
DL2MAN has now changed the license to Creative Commons but, of course, to comply manufacturers need to mention the source and re-publish their version under the same license.

So, all the materials are now available for legal manufacturing.

Manuel is clearly angry about the way he has been treated by the Chinese manufacturers who have stolen his work, without attribution and are profiting from it. There is an update of the design and Manuel feels it could be made for about $50 soon.

There's a video here that compares Manuel's latest version with one of the Chinese clones.

Friday, October 01, 2021

It's a good idea to update the Arduino IDE

There's some tribal knowledge around about Arduino IDE (and library) versions. I've heard from people that a certain version is the one that works and they don't want to update. Partly this is because they are using an old library and new code "breaks" the build.

Recently, I was talking with Paul, VK3HN, and he mentioned that he had a sketch that, when built for an Uno, was short of RAM.

Paul sent me the code, I compiled it, and didn't get the warning.

This was puzzling of course. I figured it could be one of two things:

  • One of the libraries had been improved to use less RAM
  • The gcc compiler bundled in the IDE had improved.
Here's the compile output from Paul:

Here's my output:

The figure is dynamic memory use:

Paul: 1539
Mine: 1132

Quite a big difference if you only have 2048 bytes of RAM.

It turned out that I was on a slightly later version of the IDE 1.8.15 (not even the latest) and Paul was on 1.8.12.

I tried the beta of Arduino IDE 2 and got the same memory use so I think the version of gcc bundled in it is the same. 

gcc has lots of options and, while I understand the Arduino IDE wants to keep thinks simple, it would be good if the compile options were exposed.

The lesson out of this is that the tools do get better and it's a good idea to upgrade.