Tech news spot on ABC Radio

Nightlife Tech Guru Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. This week: Apple Intelligence launched in Australia. The way we search is about to change profoundly, and there are new scams to watch for this Christmas. 

https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104738420 

MeSQUAREs alternative - 1/32" board

MeSQUAREs are excellent. I've purchased them from QRPme in the past and used them with great success. I get through them very quickly and find it a bit unfortunate that the postage costs more than the product. 

I've been looking at ways to do copper board prototyping in various ways including recently cutting circular pads.

Cutting copper board is difficult. It can be done with a hacksaw or Dremel but it's a tedious process and it's very hard to make small bits of board. The obvious answer is to use "tin snips" to cut the board but I find it splinters badly. 

Recently I discovered 1/32 inch copper board. Kevin, VK2KB, kindly sent me a few boards and I ordered some via eBay. It seems to be used for some sort of craft activity. It cuts quite easily:

I've been able to quickly manufacture a collection of useful little squares:

As an experiment, I've built a simple, one way, 10dB gain, Termination Insensitive Amplifier as described by Wes Hayward, W7ZOI, and Bob Kopski, K3NHI:

It works nicely! The copper does curl a bit when cut but I found it can be superglued down quite easily. I used a weight on the long power rail shown above.

Here's how I hold components while soldering the first lead:

My second attempt at a TIA is much more compact:

TIAs are very useful and I thought it might be nice to get some PCBs for them. I have bought from MostlyDIYRF in the past but the shipping US->Australia is extravagant. Looking around I found that Craig Weston has done a PCB design in KiCAD and generously shared it here.

Tech news spot on ABC Radio

On ABC Radio Nightlife I talked about Australian Government's efforts to reign anti-competitive actions by multi-national tech giants. Also age verification approaches, disruption of Uber, AI at the Commonwealth bank and how to kill an Ear-worm.

https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104680640 

AI noise removal from off air single sideband

The applications of AI (machine learning) to radio are fascinating me at the moment. This is a simple experiment where I recorded some SSB and fed it in to an AI noise remover at https://audo.ai/noise-removal This video switches between the input and the resulting output.

This was done just with the default settings. No training on just the noise was done. I think it does a very good job. My guess is that with modern CPUs and ML chips it should be possible to do this sort of processing in near to real time.

 

The Computer History of Australia - video series

Check out this trailer for a program covering the history of computers, and microcomputers, in Australia. So many memories for me.

"An in-depth look at the history of computers in Australia from 1949 to 2024. The series of episodes are currently in production and will be released as soon as possible."

I built many of the boards shown including the MiniSCAMP, EA 2650, Talking Electronics TEC-1, I also owned a Dick Smith System80 and a Kaypro II.

My thanks to Stephen, VK2BLQ, for alerting me to this gem on the State of Electronics channel.

Episode 1 is out:

Ralph, VK3ZZC, and I are planning a trip to visit CSIR MARK1 here in Melbourne next week.

Machine learning comes to amateur radio: FreeDV RADE

FreeDV, which bundles up the very low bit rate voice codec, Codec2 and an Orthogonal Frequency Division Multiplexed (OFDM) modem that can send the data over an imperfect HF channel using an SSB radio. 

The project gives us the ability to have a pretty good sounding digital voice contact which can be free of the background noise we are used to with analog HF radio. Amazing.

The new mode, which applies machine learning to both the voice codec and the modem, is Radio Autoencoder (RADE). "It combines Machine Learning (ML) with classical DSP to send high quality speech over HF radio at SNRs as low as -2dB. The speech signal has an audio bandwidth of 8kHz, but the RADE V1 signal requires just 1500Hz of RF bandwidth."

I'm a bit sad to see codec2 being superseded by the FARGAN speech synthesiser which is based on work by Jean-Marc Valin. Codec2 by David Rowe VK5DR, is a world leading low bit-rate codec with the added utility of being open source. I'm sure it will continue to live on for constrained computing applications.

I like to use Linux in the ham shack and don't mind building open source software. To get RADE you need the version 2 fork of the FreeDV GUI application. It's early days and I ran into some build problems. I posted to the digital voice Google group and was quickly assisted by the author of the GUI application Mooneer Salem K6AQ and Barry Jackson G4MKT who has published a very nice build script that worked flawlessly for me on Linux Mint 22. 

The machine learning parts are made with python, not uncommon for machine learning code, but it does make the build rather complex due to not only c/c++ dependencies but also python modules being required. The plan by the developers is to port the ML parts over to C++ in the future which will simplify the build and reduce the size.

The flow charts on the left show the "traditional" architecture of FreeDV on the left compared to the simpler ML based architecture on the right. The AI architecture is "simpler" in one sense but on the other hand is much bigger and more resource hungry.

There are ready to run builds for both macOS and Windows available here. (Note that this link will age so you should check for later builds). On macOS I ran into the issue mentioned at the top of the page where I opened FreeDV and got a message saying that the application was damaged. The solution is on the page, in terminal run:

xattr -c /Applications/FreeDV.app

The screenshot above shows it running on an M2 MacBook Air, receiving FreeDV's most enthusiastic user Jose Donnari from Argentina.

I'm having a bit of trouble finding people to talk to with this mode at present so to test it I transmitted on 40m and captured the signal on the excellent Ironstone Range SDR in South Australia. A path of about 700km. The recorded audio is played back in FreeDV which shows how it would be decoded by a station at the other end.

You can see there is deep selective fading on the signal but compared to past FreeDV modes there are no "beeps and burps". Another noticeable improvement is the muting when there's no actual signal seems vastly superior.

Given that this signal fits in about 2kHz of HF bandwidth, I think it's much easier to listen to than SSB once you get used to it.

There's starting to be quite a bit of activity. Here are two stations in South Australia talking on 40m, about 700km away. Even when one went to low power reception was excellent.

It's early days but this new application of machine learning to radio seems very promising. The pace of development of machine learning is breathtaking and my congratulations to David Rowe and the team for being at the cutting edge. The other big application of machine learning I can see is noise removal in HF receivers. I wonder how long it will take for commercial equipment to include this.

Tech news spot on ABC Radio

Scammers are a real threat to us all. Australians lost billions of dollars last year. Nightlife Tech Guru Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104622796 

Rosebud Radiofest most entertaining

Lots of useful parts for sale at good prices. I bought PL-259 crimp connectors for $3 each instead of the much higher prices I see them online. Tempted by one radio but the seller didn't accept my offer. Probably should have stayed until the end but it's a long drive back to Drummond. I did buy a few books and a nifty hot air gun.

It seemed a bit quieter than last year but there was lots to see.

Mostly, it was great to catch up with friends. Here's Peter, VK3YE being sold morse keys by Drew VK3XU:

Andrew, VK3BEK; Ralph VK3ZZC (who purchased yet more test equipment), Dave VK3ASE:

I bought a few books including the excellent "radio handbook" by William Orr. 

I looked it up on Amazon and find that a new copy is on sale for $749!

Jim, VK3ZKK and Judy VK3FJAD were representing the Radio Amateurs Old Timers Club.

As always, a very well organised event. It's marvellous to see the big signs on the roads leading up to the venue.

Tried Apple Vision Pro - a glimpse of the future

The Apple Vision Pro is a product they've been working towards for many years. The software progress has been public, in the form of ARKit, and the hardware in private. It shipped early this year and, while I've read many reviews, it's something I wanted to try myself.

You can book a personal 30 minute demo at Apple stores and it was easy to get an appointment.

The first step is that they put your glasses (if you wear them) in a machine that figures out your prescription. I had mine with me but they preferred to let the machine do it. My sight requires astigmatism correction and the magnetic clip in lenses they came back with seemed good.

There are some new user interface gestures to learn. Basically you "point" at things just by looking at them and "click" by touching your thumb and forefinger. It's hard not to try to point with your fingers at first.

After putting the headset on and adjusting the straps to keep light out the magical thing is when the outside world appears thanks to the high resolution cameras and high resolution screens in front of your eyes. It really looks like you're looking at the world through glass. Perspective seems the same and it's high dynamic range.

The first thing I did, which perhaps puzzled my demonstrator, was turn my head side to side rapidly to test the refresh rate. It's good but not perfect, the scene got a bit choppy.

There's a bit of calibration to do, looking at dots in front of you etc. It worked well.

Then a bunch of demos to run through. 2D photos, 2D video, 3D photos, 3D video and "immersive" photos and video. I have no interest in sport but the 3D video of basketball was quite impressive.

Most iPad apps can be used in a floating window and I looked up my WSPR Watch app in the App Store but it wouldn't let me install it.

The most impressive thing to me was how solidly user interface elements seem anchored in place around the room you're in. You can surround yourself in "windows" and pull or push them away.

The headset is bulky but didn't feel heavy on my head. After wearing it for about 20 minutes it did feel a bit hot and was a bit of a relief to take off. I could certainly imagine wearing one on a flight to privately watch a movie but I think that would be a waste of the technology.

I saw a couple of minor glitches during the demo but overall it was a solid platform.

The jury is still out on the future of spacial computing. One day the big flat screens we put on our desks will seem as dated as the deep CRT screens we used to use.

It was great to try this out. If you have time, take the opportunity. There was zero pressure from the demonstrator to have me buy one. At AU$5,000 and up, I wasn't tempted. If the price comes down to something similar to an 8k monitor they'll sell like hot cakes.

ChatGPT is incredibly useful for electronics calculations

When I wanted to calculate something in the radio shack, I used to google for the formula and then execute it on a scientific calculator. Just now I wanted to know "5dbm as peak to peak voltage across 50 ohms" so I asked ChatGPT which responded very helpfully:

This is really useful. I look forward to having it built in to my phone.

Having said that, this interesting video looking at whether high SWR causes common mode current on coax points out that ChatGPT isn't always correct but is useful.

Hole saw pad PCB construction

I generally use superglued on MePads from QRPme but burn through them at a great rate. Recently I had a go at cutting insulating tracks on PCB with a Dremel cutter wheel. 

I purchased a set of diamond (really?) tipped hole saw bits intending to use them to cut my own pads but this didn't really work as the thickness of the cut is so wide you make a big hole and get a very small pad. 

By using the hole saw to just cut the copper layer I get a nice insulated pad and it's not hard to add extra pads to a circuit under construction. Here's a diode ring modulator currently on the bench:

 MePads are great but it galls me to pay more for postage than the product. I wonder if a PCB manufacturer can make something like them?

Tech news spot on ABC Radio

Peter Marks, software developer and technology commentator from Access Informatics joined Dom Knight with all the latest in tech news. It's been 40 years since Microsoft Excel was developed, touchscreens are out and buttons are back! listen at: 

https://www.abc.net.au/listen/programs/nightlife/nightlife-technology-peter-marks/104564546

HF FM transmitter with Franklin oscillator

Recently I've been working on an AM transmitter for 40m. It occurred to me that FM should be much simpler to produce. I had ordered some varactor diodes recently and first tried to FM a crystal or ceramic resonator. I can't get much deviation and the audio did not sound good.

Then I remembered a post on Soldersmoke about a largely unknown but surprisingly stable oscillator called a Franklin oscillator. It has two transistors and has a very light load on the tuned circuit.  

Rather than the variable supply transistor I fitted a 5V three terminal regulator. Coupled to the tuned circuit is a varactor diode with an electrolytic capacitor through which line audio is inserted. There's a trim pot to set the DC to the diode.

Initial results are quite promising.

The brilliant Charlie Morris, ZL2CTM, has an excellent video on the Franklin oscillator.

Thanks Stephen, VK2BLQ, for the tip.

Tech news spot on ABC Radio

A new online safety code of practice to protect children online has been released by the Digital Industry Group for public consultation. The key principles of the codes is to protect and support children and provide all end users, including parents, with more control over what their children see, read and hear while protecting privacy. Nightlife Tech Guru Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. Listen here

3LO turns 100

The (now ABC) station called 3LO turned 100 last week. The ABC pulled out all the stops to put on a wonderful live broadcast followed by an ex-staff party in Melbourne. 

I've heard that everyone who was asked to perform was more than keen to be there. Aside from amazing musicians there were many notable celebrities in the crowd.

The first guest was no less than the Prime Minister, Anthony Albanese, who was wearing ABC Sox.

Some names that stood out for me included: Brian Nankervis, Colin Denovan, David Anderson, Deborah Cheetham Fraillon, Jacinta Allan, Jacinta Parsons, John Pesutto, Jon Faine, Mark Seymore - (hunters & collectors), Paul Higgins, Pete Smith, Peter Couchman, Raf Epstein, Red Symonds , Sarah Blasco, The Teskey Brothers, Tina Arena, TISM, Vicka & Linda Bull, and Virginia Trioli.

Danny Tran was there doing interviews for a TV news spot. Daniel Ziffer was sitting behind me. (I wanted to tell him how much I enjoyed his coverage of Sam Bankman-Fried's hair).

The show opened with the ABC news with the theme played live. Here are a few clips:

The Athenaeum Theatre was a wonderful venue for all this.

WIA historian Peter Wolfenden, VK3RV, kindly sent me this list of the first stations:

Warm thanks and congratulations to the team that put all this together. A memorable event.

As well as those of us who've worked at 3LO in the past, the current staff gathered for a photo:

John Amies wants to know why Peter Evans wasn't there.

Comms Connect Show in Melbourne

Today I joined some other amateur radio operators at the Comms Connect trade show at the Melbourne Exhibition Centre. Check in was efficient. Ralph VK3ZZC, Peter VK3YPG and Nigel VK3DZ were there too.

It was mostly pretty dry commercial stuff but Icom was there and even had some amateur equipment on display. Knowledgeable Craig Norris was there with all the Icom news.

Kenwood had a stand but there was no amateur gear, mostly DMR commercial stuff.

Telstra had some sort of life-saving drone idea but "it's going to have to be at least three times bigger than this" to be useful.

After the show we went for a very nice Yum Cha and then headed for one of Nigel's family bars "The Sherlock Holmes Inn".

Very nice. My thanks to Ralph for the bag of semi-conductors and happily I had a bag of NE602s for him.

On the train home I ran in to Ray VK3ACR, the world if full of Amateur Radio operators if you pay attention.

QRP Kits Easy Receiver

As a refreshment after all my recent home brew activity I built a nice little direct conversion receiver kit from QRP Kits aka "Pacific Antenna".

It's a classic NE602 + LM386 direct conversion receiver as described in Experimental Methods for RF Design. I've built these before. This version ads an RF bandpass filter to the front end and has an unbalanced audio chain to the LM386. It drives headphones just fine but is a little soft into my bench receiver.

Even though it only covers a small portion of the band - you move that portion with the trimmer capacitor - tuning is very sensitive and they do suggest that a multi-turn pot would be a good idea. I find it drifts a bit. Some of the supplied capacitors had very tiny and indistinct markings but the kit went together well and it worked on first power up.

Here it is receiving a parks operator:

The documentation is good and available on the web page. My kit arrived here in Melbourne, Australia, three weeks after ordering. Pretty good.

With a bit of board trimming I was able to fit the receiver into a low cost compact case.

"Socketry" this is called.

It seems more stable now that it's boxed up securely.

Tech news spot on ABC Radio.

I was a guest on ABC radio's "Nightlife" program talking about the amazing "audio overview" feature of Google's NotebookLM that generates a conversation about a topic you give notes on. 

Also Pig butchering scams are targeting Australians and are social media platforms really biased against conservative users? 

Listen here:

https://www.abc.net.au/listen/programs/nightlife/nightlife-tech-talk-with-peter-marks/104446916  

Dremel cut PCB construction

Prototyping small circuits where it's not worth designing and etching a board can be done in many ways. I've used "ugly" (which I think is rather beautiful) where components float above the copper ground plane; MePads where small copper pads are superglued to the base plane; or strip board with track cuts.

Recently I've converged on a system that's working quite well for me.

The circuit is drawn out in pencil and the outline of the PCB rectangle is traced.

Working through what should not be connected to what, I draw the cut lines under a spaced out version of the circuit. Here's my drawing and below the final working board.

I mark up the board with the planned cuts.

To make the cuts in the copper, I lay the Dremel with a cutting wheel on the bench and lean it so that it just cuts the copper. I draw the board along the wheel, leaving the Dremel stationary. I can get pleasingly straight cuts this way. It is worth checking for non-conduction between areas with a multi-meter as sometimes a strand of copper can be left at a corner.

To hold components against the board for soldering you need some sort of "helping hands" but the one I learned about from an Adam Savage video is called Omnifixo. They are not cheap but are well worth it for all the cleverness.

For years I've been using a little, rather low power, bench soldering iron but I find that quite a lot of power is needed when soldering to large copper areas. I have switched to a 70W iron and it is a revelation.

Naturally, I first had the transistor in the wrong way around, but after that was fixed. The joy of oscillation was experienced.

I'm sure this is not news to any readers but I thought it worth documenting for some who might be getting started with home construction. It's not as compact as other techniques but lends itself to making changes.

One other thing I do these days is add an LED (and resistor) to the power line. It looks nice and I can't tell you how much time I've wasted wondering why an un-powered circuit doesn't work!

Experimenting with an SSM2167 compressor limiter board

The home brew AM transmitter on the bench at the moment has thrown up the issue of either low or over modulation from my mic audio. Some time ago, I purchased a couple of interesting boards described as "SSM2167 Preamp Compressor Limiter Noise Gate Dynamics Processing Module DC 3V-5V Microphone Preamplifier". They are under AU$5 from AliExpress and really tiny.

To aid with experimentation, I've mounted mine on a carrier board.

R1 on the board controls the noise gate, which I'm not too interested in. R2 controls compression and came with a 1k resistor in place. The data sheet has this table:

1k would give almost no compression. A strange choice given how the boards are marketed. Happily there are big through holes available on the board for both resistors.

With the un-modified board I fed a 1kHz tone in and get peak to peak voltages:

50mV -> 440mV

100mV -> 880mV

200mV -> 1.43V

Higher inputs do not give higher output. The output waveform looks pretty good, so not clipping. Gain is rather low for my dynamic mic however.

I replaced R2 with a 100k resistor and it has much more gain.

5mV -> 880mV

10mV -> 960mV

20mV -> 1.06V

Output level stops there and again gain is being reduced.

Stephen, VK2BLQ, brought this idea to my attention as it has been discussed as helping the uBitx radios.

First contact with home brew AM transmitter on 7.125

For too many weeks I've been tinkering with a small transmitter for the active AM frequency of 7.125Mhz and just now I called CQ and was kindly answered by Ross, VK3ARW. He reported good signal strength both where he is (west of Bendigo) and on the Ironstone ridge SDR in South Australia. The transmitter is home brew (although I used a Jaycar mic preamp kit).

I've been testing by listening to myself on the PKLoops SDR.

The transmitter uses an Arduino Nano that simply boots up and tells an Si5351 to put out 7.125MHz. There's an RF buffer using a 2N2222. The magic happens, the generation of AM, using a simple diode ring mixer that is set to be off balance. Mic audio, from the preamp, is fed in and out comes AM. (This technique was mentioned by Dave, VK3ASE, who also uses it). There's another 2N2222 gain stage then a low pass filter. Next I have the three stage RF power amp from Drew Diamond's 80m transmitter. Finally another low pass filter for 40m.

To answer Ross's question.. out of all this I get about 1.5W so, for the sake of getting some contacts I've fed this in to a little RF amp that gives about 25W peak.

I must say I'm astonished that I didn't get RF feedback or other instability given the construction. Despite Ross's kind words on the audio I can see that a peak limiter is needed to keep modulation up without over-modulating.