Operating on 20m with good initial results

I was pretty depressed about the terrible interference on 40m here during the week. Happily on Saturday it stopped. My hope is that either it was some equipment, perhaps a welder, that is only in use from time to time, or perhaps it's something from a business that won't be running on the weekends.

The back yard isn't big enough for a 40m dipole so I measured out some speaker wire for 20m and have strung it between the window on the first floor at the back of the house, to a painter's pole on the fence (which holds the balun), and the corner of the garage.

Quickly I had received stations in New Zealand and Perth. My first transmission, with 10W is shown here on the right and I'm clearly getting out well. I've reduced power to 5W now.

This is great news and I think the dipole can be improved by suspending one leg from the tripod on the garage roof that holds the 2m/70cm vertical. You can see the dipole here, not great, but working.

If the interference comes back I will go for a walk again and try to find it. Even if it's back it will have less effect at 14Mhz than it did at 7Mhz so the move to a higher band will help there. Amazing that a small wire antenna in a tiny back yard get connect me with the world.

It's now Monday night and the terrible interference hasn't returned so far. I'm happy with 20m WSPR results except that I can't get to Sydney so far. Lots of contacts to North America.

3pm local time is best for 20m DX by the looks of it.

On ABC RN's Download This Show talking "Stalkerware"

This weekend I'm a guest again on ABC RN's Download this Show which is largely created by fabulous Marc Fennell.

Due to the pandemic both Ariel and I are at our respective homes. Each of us records video locally at 4k and send in the video. It's amazing how this is now possible when it seems like only a few years ago that postage stamp sized video was the state of the art.

Download This Show goes to air a few times on ABC RN over the weekend or you can listen here or subscribe to the podcast.

One of the stories, this time about "stalker ware" is played on ABC News24 on Saturday morning and you can see it here:

Marc kindly let me plug GovHack which is coming up on August 14-16 and will be totally online this year.

Terrible interference on HF at new home

I've got a good antenna for VHF and UHF so it's time to get something going for HF. Unfortunately, a dipole in the back yard is picking up amazingly terrible interference. Let me know if you recognise the sound or look of this noise.

A walk around with a portable shortwave radio seems to indicate it gets stronger the further towards the back of the block I get.

It's not sunny today so I doubt it is any type of solar inverter. To me it sounds like something that is sparking, perhaps a motor?

Here's a short video where you can hear the sound it makes.

This is going to be a real challenge to overcome. 

This morning I noticed that the interference had changed to broadband noise but then it switched back to the pulse style. I went for a walk along the lane behind our house.

It seems to be maximum strength behind the neighbour's back shed. I'm wondering if it's a solar charge controller or similar.

The noise has stopped. The noise floor is still pretty bad but the terrible pulsing interference stopped some time on Saturday afternoon.

As we say in programming: bugs that go away by themselves come back by themselves. I will continue to monitor the situation and improve my antenna. 

Google Pixel Buds vs AirPods Pro for an iPhone user - review

Rather than reading the instructions and using an Android phone - which I’m sure is the optimum experience - I’m reviewing the new Google Pixel Buds earphones with an iPhone running iOS 13 and just normal assumptions about how Bluetooth headphones work. My daily headphones are Apple AirPods Pro which work pretty well as you’d expect.

The plastic case is a matt white finish that looks great. The lid is held with a magnet and flips open easily. Two LEDs light up white. The bottom of the case has a USB-C charging port. (I am a big fan of the future world where everything is USB-C). The case is a similar size and shape to the AirPods case and would be as comfortable in a pocket.

With the case open, but the buds still in there, the phone’s Bluetooth screen showed them and they quickly paired. (Contrary to the instructions, I didn’t need to hold the pairing button, maybe that’s needed for additional pairing).

Inside the box are alternative silicon tips, larger and smaller. I found the medium size tips fine in my ears. Also supplied is a high quality USB-A to USB-C charging cable and a little booklet.

The shape seems a little weird and they distinguish themselves from iPods by having an upward projection compared to Apple’s downward stork. They are very comfortable in my ears.

Compared to AirPods pro, the Pixel Buds seem to have a little more bass and a little less top end. They sound fine.

Latency, the delay in sound, is much longer than with AirPods. Typing on the keyboard on the phone shows this clearly. Latency is not a problem when listening to music and it’s certainly well under half a second so won’t be a problem on calls but my guess is that Apple is doing some of their technology stack magic to win the latency war.

Tapping either side sends a play/pause signal. Swiping adjusts volume - something which AirPods lack. I found the swipe gesture a little difficult to get right but this turned out to be because I had assumed that it was swipe up for louder and down for softer - turns out you swipe forwards to increase volume. Other touch controls are double-tap for next track, triple-tap for previous track. All of these controls work with iOS.

Removing an AirPod from your ear pauses playback, the Pixel Buds don’t do this - a feature I miss.

AirPods Pro have noise cancelling, which Pixel Buds do not but the ear seal seems ok except in busy streets. I do like the noise cancelling and transparency modes that AirPods Pro have but you do pay in both price and battery life for these features.

The microphones I tested by recording in the Voice Memo app. They sound clear and, I think, better than the mic system in AirPods Pro for a straight recording.

On a phone call I found the Pixel Buds blocked my ears so my own voice sounded muffled to me. The AirPods seem to feed a bit of voice back into the ears so speaking on the phone felt better. The person on the other end of the call preferred my audio with the AirPods compared to the Pixel Buds. It may well be that they work better on an Android phone.

In summary, The Google Pixel Buds are a quality in-ear headphone with good sound. The volume control gesture is welcome but the lack of noise cancelling and fold-back made them not quite as good in phone calls on an iPhone.

Pixel Buds are AU$279 from Google compared to AirPods Pro at AU$400 so I think they are an excellent headphone for the price.

My thanks to Google for supplying a review unit.

New antenna for 144/432Mhz now up on the garage

I'm very happy to report that my antenna drought is over. Today, Khan, The Antenna King mounted my 2m/70cm vertical on a pole on the roof of the garage.

Previously I had tried to get someone to put it on the roof of the house but it's a two level roof with very steep sides and, apart from being dangerous for the installer, it would have been impossible for me to get up there to do any maintenance.

Mounting the antenna on the flat roof of the garage means it's easy to work on. The drawback is a longer coax run. Tests so far show excellent signals from repeaters around Melbourne.

Currently I'm running WSPR and only hearing VK3DXE. I'm transmitting 10W and so far no one has spotted me.

The focus for now is 2m but I've also run two pieces of RG58U out to the back yard with the intention of adding a 20m dipole and whatever else I can come up with in very limited space.

I should add that I did not do the roof climbing but merely supervised. Here's a picture Phillipa took showing the limit of my management.

The 2m antenna is working well and tonight I had simplex contacts with Ralph, VK3ZZC and Chris, VK3AML.

Great book: "Radio Girl: The story of the extraordinary Mrs Mac"

I'm currently enjoying "Radio Girl: The story of the extraordinary Mrs Mac, pioneering engineer and wartime legend" by David Duffy. It's a terrific story of early radio in Australia and the remarkable career of Mrs Mac, the first, and at the time, only female electrical engineer in the country.

Mine is the Kindle edition but it's also available in Paperback.

Peter, VK3RV, (fellow FreeDV enthusiast) mentioned the book when we spoke recently. Thanks for the tip!

macOS Big Sur is going to need larger screens

Apple has released an early version of the next macOS known as Big Sur. When I ran it on a Mac mini with my normal 4k screen my first thought was that I had the screen resolution wrong. Here's the current macOS "Catalina":

Here's the new "Big Sur":

As you can see, the dock is the same but the user interface elements in everything else is more spacious. I tried setting the screen resolution to the next sharp option and it was too small.

I like the new look. It is more consistent with iOS. I do like using small laptops though and I hope there's a way to scale back the size of elements a bit.

Both iOS 14 and macOS 11 betas seem much more stable than the versions released at this stage last year. Happily my apps work fine and even build for Apple Silicon without any obvious issues.

Update: my mistake, Catalina was scaled.

I didn't realise that I had my Catalina OS set for scaling to show more. When I tried scaled options under Big Sur they all look more blurry than what I see with Catalina. (You'll need to click on these to enlarge them).

Lots more VHF activity in Melbourne compared to Sydney

Since moving to the new home here in Melbourne I've been trying to get some antennas up. I've purchased a vertical for 2m and 70cm but so far two antenna installers have not been keen to climb on the roof here and put it up. One says he'll come back when the weather has been dry for enough time for the metal roof not to be slippery.

In the interim, I've mounted a painter's pole to the fence and put the vertical up in the back yard.

I sat outside last night (a Wednesday) and listened around on 2m. Amazing amount of activity compared to Sydney - perhaps it’s because Sydney is very hilly and not so good for VHF.

From 20:00 there was an active net on 147.250 FM. Peter, VK3RV could be heard direct! I heard the WIA news broadcast on 147.175 FM. At 20:20 I tuned to the MERC net on 146.700 FM.

I've read that there is an SSB net on 144.100 and I listened and called at 20:30 but heard nothing.

Tuning around I found an active net on 144.150 which VK3MQ referred to as the “150 net”. I could receive VK3MQ very well and when he moved his beam he came up to S9. No other stations were strong though.

It wasn’t freezing outside last night but not an ideal operating position as I have to bring the gear in after use in case of rain.

While out getting some permitted COVID exercise this morning I noticed this amazing antenna on Clarke Avenue, Northcote. I will try to figure out who it is.

Something to aspire to? I'll be happy if I can get coax from my radio room to the back yard for a small dipole.

Interviewed on ABC Sydney

A pleasure again to be a guest on ABC Sydney breakfast with Robbie Buck and Wendy Harmer. I was on to talk about the Apple World Wide Developer Conference announcements but the interview covered a wide range of topics in the end.

My bit is in the audio here but you'll need to spool right through to about 3 hours and 26 minutes.

My internet here hasn't been connected to cable yet so unfortunately I'm on the phone. Re-scheduling the NBN connection is a story in itself.

My thanks as always to the hard working producers Stephen and Yuske for thinking of me in relation to one of my pet topics.

Vinyl record stores in Thornbury

We are settling in to our new home in Thornbury, Victoria. We're out of the rental place in Alphington and happily new tenants were found to take over the lease.

Each day I walk around the area and one thing is striking - there are lots of vinyl record stores plus shops with record players and even loud speaker repair is available.

On ABC RN's Download This Show

I haven't done a Download This Show since social isolation and also moving to Melbourne so it was fun to see how the technology has changed.

The (full) radio version goes to air a few times on ABC RN and one of the stories is shown on ABC News24 TV. You can see it here:

Initially I set myself up on an office connected via Wifi but we had audio problems and so I had to quickly re-locate next to the cable router and connect with ethernet. Video was recorded locally with an iPhone SE 2020 set to 4K 24fps and it looks passable on a big screen. Amazing what a phone's selfie camera can do these days.

Always good to talk with Marc and great to meet Sarah Moran who is based in Melbourne, where I now live.

Honest and dishonest reviews of the Spy Gear walkie talkie

Facebook's targeted advertising knows me too well and lately it's been repeatedly showing me ads for a pair of transceivers priced at just AU$15.

I wondered what frequency they are on and if they might be moved to a ham band just for fun.

When I was young my dad bought me a pair of 27Mhz transceivers and these were absolutely fascinating. All sorts of hide and seek games were devised where the hidden person could talk with the searchers and taunt them. CB was popular at the time and sometimes trucks could be heard and even remote stations in the evening.

Drilling in to the reviews on Target's web site soon reveals the truth...

But wait... there is one (incentivised) reviewer who really loves this product!

Peter, VK3YE, tests an even cheaper pair of transceivers that seem to operate better than the Spy Gear ones from Target.

Great work Peter. I would be interested to see the circuit traced out.

Currently preparing to move house here. All antennas are down and looking forward to the new QTH.

Radio communication with friends in NSW

I'm now 709km away from my ham radio buddies in Sydney. Propagation is not great and my antenna, for the next few weeks, is a very poor end fed hanging out the window.

Stephen, VK2BLQ, is humouring me and we've been trying to establish digital radio communications via 40m.

We can hear each other on WSPR, best reception was -6dB. We tried Olivia 8/250, Stephen could decode me but alas, I can't decode him. Presumably the noise floor here is too high.

Now we're trying JS8call and we had two-way communication for a short time this afternoon. The software was already in the Ubuntu software library so installation was a breeze.

The software's user interface is rather mystifying at first but after filling in your call and grid square, the trick is to wait for a call to appear on the right, click on them, enter text in the middle box (it says "TYPE YOUR OUTGOING..." and then press the Send button.

There's also a bunch of common messages in the "Directed to..." popup button.

Also, of course, you can call CQ and happily there is some activity here (unlike PSK which seems to have died).

Thanks VK2BLQ for your help with this. JS8 is more interesting to me that FT8 as you can at least have a bit of a chat with it.

Settling in to Melbourne and Joining MERC

Moving back to Melbourne after 30 years in Sydney means that I was keen to make contact with ham radio people here much as the group from the ARNSW Radio Experimenters group has become a circle of good friends in recent years in Sydney.

I joined the Melbourne Electronics and Radio Club (MERC) and was quickly and kindly welcomed by President Stuart, VK3SH and treasurer John, VK3ZX.

The club has four regular nets each week and I've joined the Wednesday & Friday nets at 8pm which are FM via the VK3RML repeater on 146.700. That repeater was down and so the net moved to a repeater on 438.225. This is good as I have much better reception of this one anyhow.

Stuart kindly sent me five recent editions of the excellent "MERC Almost Regular News Letter" which has a good sprinkling of home brew radio construction including antennas, filters, audio amplifiers, antenna switches, and also some wonderful shack photos.

I look forward to pandemic restrictions being eased so we can meet in person.

For now, I have a minimal shack set up.

I look forward to the day when all transceivers have a single USB socket with both audio and control over USB. It will make computer connection much less messy.

Virtual audio cable for macOS

Forgive me if this is old news but on Windows I've long used the excellent and free VB-Cable from VB-Audio Software for piping audio from SDR# into WSJT-X.

I mostly use macOS and Linux but for some reason SDR# seems to be the SDR software I like the most and it only runs on Windows.

A 2012 MacBook Pro is used to dual boot Windows for running this stuff as you see above right.

Today I noticed that there is a version for macOS and so far it looks good. (The software is free but "donation ware" and I've send them US$10 in appreciation of the macOS version).

A new device simply appears as an input and output device and settings are available in the Audio MIDI control panel.

I'm aware of Rogue Amoeba's Loopback but it is US$109 and seems more complex than is needed for this basic task. Their other software is excellent though.

What WSPR signal to noise ratio is needed for sideband to be intelligible?

The end-fed antenna is working pretty well on 40m and I'd love to have a contact with Sydney friends. John, VK2ASU, kindly agreed to run a WSPR beacon so I could find the best times to receive him.

Over a 24 hour period, with him transmitting just 10mW, the best SNR was -21dB here.

My question, to the brains trust hopefully reading, is what WSPR signal to noise ratio would be enough such that a higher power sideband call would be audible?

I have read that a signal to noise ratio of 6dB is needed to be able to copy SSB.

John is transmitting 10mW which is 10dBm but he could run 100W on sideband or 50dBm. An extra 40dB.

If the bandwidths were the same then -21dB + 40dB = 19dB of signal to noise but while SSB is about 2.5kHz wide, WSPR is much narrower, perhaps only a few Hz?

Here is the SNR between VK2ASU and VK2TPM (portable VK3).

Spots from all stations to me looks like this:

Any insights or pointers gratefully received.

Kevin, VK2KB, commented: "My understanding is the noise power doubles every time the bandwidth is doubled while the power level of the received signal stays constant. I've verified this on my SA by changing the bandwidth of the SA response and noting the noise floor, you can see the floor decrease by 3db every time I halve the  SA  window but the amplitude of the signal I'm watching stays the same.  With WSPR you need to know what the effective bandwidth is. I had a look at this site:

https://en.wikipedia.org/wiki/WSPR_(amateur_radio_software)

They say the effective bit rate is about 1.5 baud  and its possible to recover a wspr signal at -34 db  on a 2500Hz bandwith rx.

Say that you are using an effective bandwidth of 1.5 Hz to recover the digital signal the ratio of 1.5/2500 =  .0006 or -32db  Because the wspr signal is coherent I think they get a few more dbs in the demodulation process.

The difficulty with this is however the power bandwidth of the wspr signal vs the power bandwidth of the ssb signal.  Anyway something to spend time on."

Update October 2023

Reader Math Pantus, PA3BUL, wrote an interesting response which he gave me permission to post here.

WSPR was made to be detectable 12dB below a

CW signal. 

So that we obtain an indication of

a propagation path that started to open up.

[about 2 S-units below]

CW vs SSB difference in readability is just

about 30dB.

> So 1Watt of CW is worth about 1000Watts in USB

for readability.

Here are the reasons for CW to be so readable:

1) CW 1 Watt (Key-Down) is 1 Watt

   USB 1 Watt is just .25 to .35 Watts due

   to the Peak-to-Peak versus average voice

   power. Screeming AAAAAAAH will give you

   .3 Watt and with the best compressor you

   will get .35 Watts. At .4 Watts readability

   suffers a lot.

2) Bandwidth of CW is just about 0.8 * WPM.

   So over 15 WPM confusion increases much.

   The bandwidth of your CW IF filter is

   enhanced with your brain expertise that

   brings the readability very close to the

   0.8 * WPM limit.

   This because of psycho-acoustic effects.

   

   The same effects that can compress music

   into MP3 format with less that 10% disc-space.

 NOTE:  U wide CW roofing filter can be just as good

 as a narrow one. Just more fatigue will be the result.  

For a voice to be readable we need just 20dB of

Signal to Noise margin.

Using the NATO words for spelling, we can creep by

with 15 to 16 dB of SNR.

(As the use of NATO words is a form of FEC,

Forward-Error-Compression).

>So 1Watt of WSPR is just as good as 16 Watts of CW and 16 KWatts of SSB.

NOTE: K1JT refers all WSPR signals to 2500Hz of receiver bandwidth.

            this makes it easy to compare.

My try at answering your question is:

If WSPR signals come in at + 42dB or more, you could pick-up the Mike and give it an SSB try.

NOTE: WSPR encoding uses: Data compression, redundancy, FEC, pseudo-random time slots, DSP

      narrow-band filtering synchronous detection.

      All in order to enhance de-code ability and selectivity.

      Also reducing the effects of QSB, QRN, and QRM.  

 

>The compression is like a PKZIP compression of the call sign plus QRA-locator.

> After compression, to the compressed data, redundancy is added.

> During the transmission the receiver and transmitter hop-skip and jump through the

   same time-slot. It is like encryption where the key is determined mathematically at both

   sides. This method avoids data clashes and corruption by QRM, QRN and QSB.

   Therefore WSPR can be used in cities with lots of QRM.

NOTE: WSPR lets a poor antenna look good.

            WSPR lets a good antenna look sublime. (Look at VK3MO   wspr results)

      He uses just 5 Watts in a 20dB gain antenna. So 500Watts ERP.

      

Last NOTE: I am trying to create a procedure to use the WSPR modulation quality to

have 2-way contacts.