Wednesday, October 23, 2024
Tech news spot on ABC Radio
Sunday, October 20, 2024
3LO turns 100
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.
Wednesday, October 16, 2024
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.
Monday, October 14, 2024
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.
Wednesday, October 09, 2024
Tech news spot on ABC Radio.
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
Sunday, October 06, 2024
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!
Friday, October 04, 2024
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:
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.
Wednesday, October 02, 2024
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.
Sunday, September 29, 2024
Python code to generate WSPR audio tones
Ross, EX0AA, is working to do WSPR on very low frequencies and asked for some help generating WSPR tones as audio directly. There are several projects around that generate WSPR via GPIO pins, Si5351s or an AD9851 DDS.
I grabbed the AD9851 code from PH0TRA, removed the DDS code, and with the help of ChatGPT, modified it to generate audio directly using pyaudio. This works both on my Mac and on a Raspberry Pi with no modification. The audio comes out of the default device, and if you plug in a USB audio dongle it comes out of there.
It seems to decode just fine with acoustic coupling.
My code is here. You'll also need genwsprcode.py modified by PH0TRA from code by the fabulous Mark VandeWettering K6HX.
You'll need to use Python 3 (of course) and install pyaudio and probably numpy.
Usage: python3 wsprgen.py CALLSIGN GRID dBPower BASE_AUDIO_FREQUENCY
Thanks Ross for the push to make this. It could be handy for others.
Installing on a raspberry Pi
Thanks for the prompt from AA7US asking how to get going on a raspberry pi.
- Grab my code from the GitHub gist. (you can download the file or copy and paste).
- Grab PH0TRA's code from here. Put it in the same directory.
- Install the needed python modules:
- sudo apt install python3-pyaudio
- sudo apt install python3-numpy
- In a terminal run the program like this:
- python3 wsprgen.py --no-delay CALLSIGN GRID4 DBM 1500
Obviously replace CALLSIGN GRID4 DBM. 1500 is the base audio output frequency in Hz.
--no-delay starts outputting right away, good for testing. Remove that to have it wait for the top of the 2 minute block. You'll get a bunch of output from the audio software but it seems to work after a few complaints. Here's my output:
python3 wsprgen.py --no-delay vk3tpm qf22 33 1500
symbols
3,1,0,0,0,2,0,0,1,2,0,2,1,1,1,0,2,2,1,0,2,3,0,1,3,1,1,0,0,2,0,2,0,0,1,2,2,1,0,3,2,2,2,2,2,2,3,0,3,1,2,0,3,3,0,3,2,2,0,3,3,2,3,2,2,2,0,1,1,0,1,2,1,2,3,2,3,2,0,3,2,0,3,2,3,1,2,0,2,1,1,0,3,2,1,2,0,0,3,2,2,2,0,0,3,2,2,3,2,2,1,3,1,2,3,1,2,2,3,1,2,1,2,2,0,1,1,3,2,2,2,0,2,1,2,3,2,2,3,1,0,0,0,0,0,0,2,1,1,2,1,2,3,3,0,2,2,3,1,2,0,2
ALSA lib pcm_asym.c:105:(_snd_pcm_asym_open) capture slave is not defined
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.front.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM front
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround51.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround21
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround51.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround21
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround40.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround40
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround51.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround41
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround51.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround50
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround51.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround51
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.surround71.0:CARD=0'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM surround71
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.iec958.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM iec958
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.iec958.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM spdif
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.iec958.0:CARD=0,AES0=4,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM spdif
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
ALSA lib pcm_oss.c:397:(_snd_pcm_oss_open) Cannot open device /dev/dsp
ALSA lib pcm_oss.c:397:(_snd_pcm_oss_open) Cannot open device /dev/dsp
ALSA lib pcm_a52.c:1001:(_snd_pcm_a52_open) a52 is only for playback
ALSA lib confmisc.c:1369:(snd_func_refer) Unable to find definition 'cards.0.pcm.iec958.0:CARD=0,AES0=6,AES1=130,AES2=0,AES3=2'
ALSA lib conf.c:5180:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5703:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2666:(snd_pcm_open_noupdate) Unknown PCM iec958:{AES0 0x6 AES1 0x82 AES2 0x0 AES3 0x2 CARD 0}
ALSA lib confmisc.c:160:(snd_config_get_card) Invalid field card
ALSA lib pcm_usb_stream.c:482:(_snd_pcm_usb_stream_open) Invalid card 'card'
ALSA lib confmisc.c:160:(snd_config_get_card) Invalid field card
ALSA lib pcm_usb_stream.c:482:(_snd_pcm_usb_stream_open) Invalid card 'card'
ALSA lib pcm_dmix.c:999:(snd_pcm_dmix_open) unable to open slave
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
Waiting for next WSPR TX window...
Start of transmission on: 03:20:04
Frequency: 1,500 Hz
symbol = 3, out_frequency = 1504.39453125
symbol = 1, out_frequency = 1501.46484375
symbol = 0, out_frequency = 1500.0
symbol = 0, out_frequency = 1500.0
symbol = 0, out_frequency = 1500.0
symbol = 2, out_frequency = 1502.9296875
symbol = 0, out_frequency = 1500.0
You'll hear the tone on the default output. In my case I plugged in a USB audio dongle.
Wednesday, September 25, 2024
The Secret Life of the Radio
Thanks to Lindsay, VK3GX, for bringing this wonderful BBC program to my attention. The team shows the development of radio and makes various transmitters and receivers. They build a coherer and demonstrate it for example.
Keep watching after the end credits for some comments from the presenter.
Incidentally, the cartoon depiction of Marconi's home are quite accurate. I visited it some years ago.
Tech news spot on ABC Radio
You can listen here.
Thursday, September 19, 2024
Radio Old Timers Club AGM
The Radio Old Timers Club annual general meeting and lunch was well attended by members of MRARC. Peter VK3RV, Jen VK3WQ, Ray VK3ACR and Peter VK3TPM attended. Old friends Nigel VK3DZ and Peter VK3YPG were also there.
First the meeting kicked off with the annual general meeting which was conducted efficiently by Jim Gordon VK3ZKK with some members on Zoom.
Next a hearty lunch was served.
Mick VK3CH gave a detailed presentation about microwave operation.
Lots of gear was on hand but unfortunately wasn't turned on.
Don VK3BIG brought along what must surely be a new disruptive technology that could spell the end of FM radio - an AM stereo receiver.
Wonders will never cease! Nigel, VK3DZ is clearly boggled by this advancement.
Tuesday, September 17, 2024
50 Years of G-QRP Book review
Australian QRP and home brew enthusiasts typically subscribe to two fine newsletters, the local Lo-Key from the VKQRP club and the British SPRAT from the G-QRP club. Both are A5 format newsletters packed full of interesting projects and ideas. They are of sufficient quality to stand many re-readings over the years but it’s sometimes hard to find an item that comes to mind in the pile.
Lo-Key has an index and SPRAT sells back issues on CD or USB key.
When I heard of the publication of a book to celebrate 50 years of SPRAT, I didn’t hesitate to order a copy.
The G-QRP club was founded in 1974 by Reverend George Dobbs G3RJV (SK) who commented that there might be a demand for a newsletter “if there’s enough interest”. It turns out that there is.
Ed Durrant, G8GLM, has put together a fascinating selection of articles drawn from SPRAT over time. They are clearly marked with the year of publication and show the progression of technology available to the hobbyist over the 50 years. Beginning with low valve count gear and ending with SDR technology.
The book’s selection of projects is broken down into Transmitters, Receivers, Transceivers, Antenna systems, Test equipment, and Miscellaneous topics.
Although widely available components have changed over the years there is lots of great ideas within the collection that are still relevant today. There are charming mentions of the help that writers have received from other home brewing QRP operators.
Many of the articles mention familiar names from other writing including Doug Hendricks KI6DS, Pete N6QW, Charlie ZL2CTM, Eric ZL2BMI, Roger G3XBM, and Wes Hayward W7ZOI. There’s a good number of VKs mentioned. I haven’t spotted VK3YE, but he’s probably there somewhere.
A few of the articles are reproduced with low contrast – I guess they’ve been scanned. Early items are charmingly typeset on manual typewriters. For the 100th edition I’d like to see an index added.
The book is available via the RSGB shop for £17.99 and less for members.
Wednesday, September 11, 2024
Tech news spot on ABC Radio
You can listen here.
Thursday, September 05, 2024
High quality AM exciter using a diode ring mixer with DC offset
There is a very active AM net here on 7.125Mhz and quite a few of the stations come up with home brew transmitters. (There's also a few using IC-7300s which do sound good on AM).
Dave, VK3ASE, mentioned recently that a good way to generate high quality AM is by using a diode ring mixer (which would normally produce double sideband with suppressed carrier) but with a DC offset added to the audio input.
My build is being prototyped on a literal bread board:
In place of a 7.125 crystal I'm using an Arduino Nano that simply boots up and puts an Si5351 on 7.125. That signal is buffered with a 2N2222 before being fed into a TUF-1 mixer. (I did build my own diode ring mixer but it doesn't work as well as the pre-built ones). I buffer the output and then amplify it through a few DB139s.
Only a few watts out so far and I'm keenly aware that AM transmitters like to provide RF feedback.
The Arduino sketch is quite simple and has bits of code primarily from Paul VK3HN.
/*
Single frequency oscillator
Si5351
Based on code from Paul, VK3HN
https://github.com/prt459/Arduino_si5351_VFO_Controller_Keyer
Don't forget:
* Arduino Nano 328p
* Old bootloader
* 115200 baud
*/
const unsigned long int FREQ_DEFAULT = 7125000ULL;
const unsigned long int FREQ_CALIBRATION = 370ULL;
#include <si5351.h> // Etherkit Si3531 library Jason Mildrum, V2.1.4
// https://github.com/etherkit/Si5351Arduino
#include <Wire.h> // built in
// Global objects
Si5351 si5351; // I2C address defaults to x60 in the NT7S lib
unsigned long int gFrequency = FREQ_DEFAULT + FREQ_CALIBRATION;
void setup() {
Serial.begin(115200);
Wire.begin();
Serial.println("Starting");
setupOscillator();
delay(500);
si5351.set_freq(gFrequency * SI5351_FREQ_MULT, SI5351_CLK0);
si5351.output_enable(SI5351_CLK0, 1);
Serial.println("Output enabled");
}
void loop() {
}
void setupOscillator() {
bool i2c_found = si5351.init(SI5351_CRYSTAL_LOAD_8PF, 0, 0);
Serial.print("si5351: ");
Serial.println(i2c_found ? "Found" : "Missing");
si5351.set_correction(135000, SI5351_PLL_INPUT_XO); // Library update 26/4/2020: requires destination register address ... si5351.set_correction(19100, SI5351_PLL_INPUT_XO);
si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);
si5351.set_freq(500000000ULL, SI5351_CLK0);
si5351.drive_strength(SI5351_CLK0, SI5351_DRIVE_4MA);
si5351.output_enable(SI5351_CLK0, 1); // turn VFO on
printSi5351Status();
}
/*
The nominal status for each of those flags is a 0. When the program indicates 1,
there may be a reference clock problem, tuning problem, or some kind of other issue.
(Note that it may take the Si5351 a bit of time to return the proper status flags,
so in program initialization issue update_status() and then give the Si5351 a
few hundred milliseconds to initialize before querying the status flags again.)
*/
void printSi5351Status(){
si5351.update_status();
delay(500);
Serial.print("SYS_INIT: ");
Serial.print(si5351.dev_status.SYS_INIT);
Serial.print(" LOL_A: ");
Serial.print(si5351.dev_status.LOL_A);
Serial.print(" LOL_B: ");
Serial.print(si5351.dev_status.LOL_B);
Serial.print(" LOS: ");
Serial.print(si5351.dev_status.LOS);
Serial.print(" REVID: ");
Serial.println(si5351.dev_status.REVID);
}
Tuesday, September 03, 2024
Tim Bowden has died
ABC Radio legend and beloved presenter of ABC TV's BackChat program, Tim Bowden has died. He was a wonderful broadcaster, producer, writer and man.
Here he is with his wife Ros (who died a while ago).
We became friends when I was working for the ABC in Sydney. Mostly around Apple technical topics.
I vividly remember listening to his radio series Taim Bilong Master about the Australian involvement with Papua New Guinea. I own several of his books including Changi Photographer.
Here he is perched in the back of my van on the way to lunch a few years ago.
He has requested that there not be a funeral but I'm sure we can look forward to some well deserved tributes.
Friday, August 30, 2024
Contestia - faster, not better
Looking at digital modes for talking with people with high local receive noise I noticed Contestia in Fldigi. It's derived from Olivia but has a smaller character set. It only sends upper case letters.
Stephen, VK2BLQ, has fairly high local noise. He's about 700km from me. To check if we have a suitable path for a QSO we both ran WSPR on 40m. He received my 2W at +3dB SNR so we switched to Contestia.
I received him perfectly but he wasn't copying me. It turned out Fldigi defaults to having the squelch turned on. Turning that off and he was able to copy me running down to 5W and probably lower.
My, incorrect, assumption was that Contestia used the extra bits compared to Olivia for better error correction.
Reading from the Fldigi documentation page on Contestia.
"Contestia is a digital mode directly derived from Olivia that is not quite as robust - but more of a compromise between speed and performance. It was developed by Nick Fedoseev, UT2UZ, in 2005. It sounds almost identical to Olivia, can be configured in as many ways, but has essentially twice the speed.
…
Contestia performs very well under weak signal conditions. It handles QRM, QRN, and QSB very well also. It decodes below the noise level but Olivia still outperforms it in this area by about 1.5 - 3db depending on configuration.”
It seems the objective was faster typing speed which I don’t really think is important.
So… thanks for the experiment but I think we should use Olivia in future.
Now, looking at the Olivia page in Fldigi.
The first tip they give is to turn off (or down as much as possible) the squelch.
There’s a bit of talk about different sub-modes but it seems to be about getting faster speed. They say if you’re on 250/8 and want faster (in good signal conditions) go to 500/8.
My question is "what is the best keyboard to keyboard chat mode for low signal to noise radio channels?".
Wednesday, August 28, 2024
Gear for a remote radio guest - Mix minus
Regular readers will know that I'm one of those commentators you hear on the radio. I've always been keen to have my audio sound as close to the studio as possible and I think I'm getting close.
Richard, VK3LRJ, had just the device I needed. It's a Behringer Xenyx 302USB. These aren't new but have the ability to let me hear the mix while sending just the mic up the line. It's also a USB sound card so plugs in to the computer and is powered from that USB port.
One interesting note is that it says the XLR mic socket has phantom power but my Rode mic didn't work. Turns out the phantom power is about 14V rather than the 48V norm so some microphones work but others don't. I'm using a Sure dynamic mic, similar to the studio. These mics have quite low output but this mixer has enough gain.
Anyhow, here's the latest appearance:
Telegram is just one of many messaging apps, being targeted in France over secure messaging, but just how secure is it? AI is the biggest development in technology, and it seems it's also the job that pays the best. Plus, growth in the PC and Phone markets has been slowing, and the next big thing that may stimulate people to upgrade their PC and phone is new AI features that the old models don't offer. Tech Guru Peter Marks, software developer and technology commentator from Access Informatics, with Philip Clark on Nightlife and the latest news and issues in technology.
Wednesday, August 14, 2024
Tech news spot on ABC Radio
As an aside, I'm pretty happy now that my audio quality matches the studio quite well despite me joining the program from my home office.
Tuesday, August 06, 2024
ePaper solar power monitor with Lilygo T5
The house here has 6KW of solar power, when the sun is shining and hitting the panels. I like to watch what's being generated so I can use power from the sun if available so some time ago I reverse engineered the Envoy inverter's web display and made some M5 Stack devices that display the info. They have an ESP-32 for Wifi built in.
Sometimes the sun also shines on the LCD making it hard to see so I've just ported my code to a Lilygo T5-2.13 E-Paper board also with an ESP32.
E-paper is highly visible although refreshing is a bit slow and ugly. The Arduino compatible libraries are available here. Things didn't quite compile as given but I was able to work through it.
The E-Paper board uses negligible power when sleeping, and the display remains visible, so these could be run from a small battery if desired.
Building a quadcopter drone from parts
It's been many years since I've built a quadcopter from parts. What triggered this project was stumbling across the SpeedyBee flight controllers which have a powerful STM32 F405 and bluetooth so they can be configured wirelessly from a smartphone app. The controller has the motor controller (ESC) board mounted under it which makes for a much neater arrangement than the last time I did this which involved have ESCs on each arm of the drone.
Here's a closeup of the flight controller with ESC board under it.
The SpeedyBee uses a version of Betaflight. It arrived with the latest version. I've added a GPS module and was hoping to get a GPS Hold mode but that doesn't seem to be available in Betaflight. There are comments that even if it were available it doesn't work very well due to the poor accuracy of GPS position.
Here's my list of parts:
Frame
FPVDrone 5 inch frame Mark4 225mm FPV Racing Drone Frame Carbon Fiber 5inch Quadcopter Freestyle Frame Kit with Lipo Battery Strap $79.67 Amazon
https://www.amazon.com.au/dp/B082SPT5D9
Receiver
FLYSKY FS-A8S V2 2.4G 8CH Mini Receiver PPM I-BUS SBUS Output for Flysky FS-i6 FS-i6S Airplane FPV Racing Drone Transmitter
https://www.aliexpress.com/item/1005005699957173.html $12.87
Transmitter
Flysky FS-i6X 10CH 2.4GHz AFHDS 2A $$57.01
Buzzer
5V buzzer $2
https://www.aliexpress.com/item/32996116481.html
Motors 2300KV
RS2205 2205 2300KV CW CCW Brushless Motor for FPV RC QAV250 X210 Racing Drone Multicopter $24.78
GPS
GPS BN220 $12.26
https://www.aliexpress.com/item/1005006319024804.html
Flight controller and ESC
SpeedyBee F405 V3 30x30 Flight controller + 50A BLS 4 in 1 ESC
$109.88
https://www.aliexpress.com/item/1005005486457877.html
Flight controller:
https://www.speedybee.com/speedybee-f405-v3-bls-50a-30x30-fc-esc-stack/
5-inch propellers
5x4x3 5040 three blade ebay.
I already had a transmitter but it's rather bashed up and getting unreliable. I also have batteries in stock.
All up about AU$250.
Once I got the propellors turning the right way and enabled Horizon mode it flys quite well. Next step is to add a camera and transmitter. This will be a good "knockabout" drone for hoisting antennas and other such activities.
Betaflight?
I was surprised to see that the SpeedyBee flight controller runs Betaflight as when I last played with this stuff the Cleanflight fork was the leading software. It turns out the modern Betaflight is now a fork of Cleanflight and is the most popular and up to date. This is explained on the excellent documentation wiki.
Friday, August 02, 2024
QRP operation from a motel room
This year I fulfilled a long term ambition of visiting Uluru in the centre of Australia and I couldn’t help thinking how spots from there might look on a WSPR map. Here's a spoiler (plotted in WSPR Watch):
Operating QRP from a motel room is a challenge in several respects. From past experience I knew that receive noise would be high and while it’s possible to hang an antenna up inside the room, getting it out on a balcony would work much better. The motel at Yalara (where the accomodation is near Uluru) had a decent but all metal balcony.
The first attempt had the wire antenna on the outside face of the balcony. Reception and transmission was not good. Our room was on the second floor and there was a small tree just across a path so a sugar packet was tied to the end of the wire for a bit of weight and I threw it out to the tree. This worked much better.
The end fed wire was cut randomly and is about 4m in length (very short for the 20m band). A small counter-poise of about 1.5m was just laid out on the floor. A QRP Z-match antenna tuner was used and a NanoVNA was used for initial tuning. The Z-match was able to provide a very good match, no external Unun was needed. No doubt there are losses but my signal was received around the world so they can't be too bad.
The Z-match has an SWR indicating LED (you tune for minimum brightness) but I also experimented with a simple RF current detector and found that brightness is maximum close to when the SWR is at a minimum.
There’s promise in this simple RF current detector and in an absolute miniature equipment setup I might opt for one of these combined with receive noise peaking to indicate antenna resonance.
Having said that, the NanoVNA is a remarkable piece of pocket sized test equipment, smaller than any antenna analyser and very capable.
Weak signal operation in a poor location begs for WSPR operation and the rig of choice for me is the QRP-Labs QDX which has many advantages including being pocket sized. I powered it from a block of 8 AA NiMH batteries which were able to run it from about 6pm until 3am local time with 10% transmission.
WSJT-X was run on an M2 MacBook Air prevented from sleeping with the Caffeinated app. One of the benefits of using the QDX is that rather than mixing WSPR audio tones up to SSB audio, Hans cleverly measures the period of the audio cycle and directly sets the RF oscillator to the right frequency. This makes for a very pure transmitted signal and I’m convinced that WSPR transmitted by one of Hans’ recent transceivers is more easily decoded than the same power from a sideband transmitter.
One 2 minute transmission was reported by 41 stations which is pretty good going given my remote location and compromise antenna.
In this case my end fed wire antenna was black insulated hookup wire. It was not easy to spot from outside and I know that some stations use wire-wrap wire which is virtually invisible even close by.
If you ever get the chance to visit Uluru, go for it. It’s a remarkable feature of the landscape.
If you will be in a motel anywhere in the world consider digital QRP operation.
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