First HF Digital Voice contact with codec2 and FreeDV

I'm very excited to report that I've had two digital voice contacts on HF using FreeDV which runs codec2 by David Rowe. (There's also a very active digital voice Google Group).
Here's how Patrick VK2PN looks to me running 5W.

This mode uses about half what a sideband radio would use and is perfectly intelligible when it's working. The other bonus with a digital mode is the complete lack of background noise.

Here's how I look to Patrick on his panadapter:

Patrick has written up our contact from his side on his blog.

FreeDV is very easy to get going on Windows, I had a go at building it for Ubuntu Linux but ran into a few bumps in the road.

Here's a video from my end where you'll hear how Patrick sounds to me as we both reduce power.


After the contact with VK2PN I was also able to talk with Graeme, VK4CAG pretty well.

So, this is an extounding day! Great work by David Rowe and all those involved. It's fantastic to have a good quality low bit rate voice codec that is public domain. This is a great thing for Ham Radio and I would think will have reverberations through the voice over IP business as well.

Update - FreeDV under Wine

Stephen, VK2BLQ, has just pointed out that FreeDV seems to run well under Wine on Linux.

Update - FreeDV now builds on Ubuntu 12.10

The latest code from subversion now builds smoothly on Ubuntu 12.10 but for me the audio stutters for some reason so I'm still using the Windows version under Wine. I just heard VK4BD on 14.236 but couldn't decode more than the call sign.

Update - FreeDV on MacOS via wine

FreeDV appears to run ok on MacOS under wine but again I'm hearing audio stuttering. It looks pretty good though:

I installed wine with brew. Note that to get it installed you need to do the following:

• brew rm libpng
• brew install libpng --universal
• brew install wine

Then you cd to the directory with freed-windows and wine freed.exe

Current project - the "Beach 40" DSB transceiver

Peter, VK3YE, is an inspirational home brew designer and constructor. In a series of YouTube videos he demonstrates and then walks through the design of a simple double side band transmit, direct conversion receive, transceiver he calls the "Beach 40".

The minimalist QRP Transceiver group has drawn the circuit up (in the files section).

I started construction over the weekend but my oscillator didn't.

I'm using the "manhattan" or "paddy board" construction technique using bits of PCB cut with tin snips and superglued on to the base board as insulating islands. It's not as compact as "ugly" construction but the circuit is more obvious and it's very low profile. I'm thinking of stacking boards one above the other in the final box.

After some tips on non-starting oscillators from VK2ASU and VK2BLQ (who's also building one), I put a variable capacitor in place of the 390pF in the Colpitts oscillator and it started.

Peter's design has evolved through the YouTube video series, mostly in the receive audio switch to an LM386 but I am attracted to the all discrete transistor version if it can be made to work. It's much quieter in my shed than it is on Elsternwick beach.

Update

Stephen, VK2BLQ, is also building and it's looking good (click to embiggen):

His CRO is much fancier than mine but I'm a bit suspicious of that waveform from modulation of a 1kHz tone on 7144kHz:

VK2BLQ is powering ahead of me:

But I own Saturday....

Update. Does this look right?

I'm still on the balanced mixer. I'm feeding in a 2.2V peak to peak 1kHz tone and here's the modulated RF output I get.

Seems very low level and somewhat non-symetrical. The variable resistor changes it but the trimmer capacitor has very little effect.

Stephen is powering ahead and now can transmit, here's his latest work (I wish mine was as good).

Stephen writes "Hi Peter, seems to be real QRP final current less than 250mA can't read any power
on  the meter.

As can be seen on the CRO, the PEP is 20v p-p which is about 250mW or 1 watt if it were CW. I think the final transistor  is not right. It is  a CB radio final and should be good for 4W. Time to cook dinner and have a look later"

Update - My power strip

Like Stephen, I'm getting 20V p-p or 1W out which seems a little disappointing.

Don't worry I will find some heat sinks. Here's a top view:

Software Defined Radio talks

Today at the ARNSW Home Brew Group, we had two talks on Software Defined Radio, one dealing with VHF and up, the other on HF. First here's Gary, VK2KYP, who kindly gave me permission to post this video. Gary has previously purchased a FunCube dongle but finds a $20 DVB tuner works pretty well and is great value.



And here's Stephen, VK2BLQ, on HF SDR:

Feld Hellschreiber QRP beacon with arduino

I have been using a digital audio recorder to provide Hellschreiber test signals but this is clearly silly. So, thanks to Mark of the fabulous brainwagon blog I now generate test signals with an Arduino.

The Arduino sends port 13 (the one with the on-board LED) high and I use it to turn on a transistor to pull my final low. Off air locally it looks pretty good and the drift is quite mild.

I'm still running milliwatts with my big 2N2222a final transistor but Stephen, VK2BLQ can hear me 10km away fairly well over the noise. Here's how I look at his place:

On Sunday, November 25 2012, Stephen and I gave a little presentation about all this at the ARNSW Home Brew Group meeting at Dural NSW:

How to fix poor iPhone battery life

My iPhone 5 wasn't making it through the day. I was disappointed, but after a few simple changes it looks like it could even last two days.

My usage pattern is that I charge over night, get up at about 6am, listen to podcasts for an hour going to and an hour returning from work.

During the day I make a few calls, and use a lot of Wifi data. On the way home I use a bit of LTE cellular data to catch up with news feeds.

With the changes below, as you can see from the Usage screen to the right, after 11 hours without a charge my battery is still at 74%.

Long life suggestions

• Avoid polling for email. I was polling for GMail every 15 minutes, I switched to the GMail client (as I use Exchange for work email). So mail is pure push and it's instant.
• Turn off LTE unless you're in a good LTE reception area and actually plan to use it. LTE is very patchy here and I've noticed the phone running hot in my pocket trying to contact cell towers.
• Screen brightness under 50%.
• Choose a carrier with good strength at your home and office. Phones turn up transmit power is signal strength is low.
• Reset network settings: Settings>General>Reset Network Settings. I'm a little sceptical about this one but it forgets all those Wifi networks you've used once and stops the phone trying to join them again, unless you specifically want to.

Using Push instead of polling is the big one I think. Push is very efficient, it's a single TCP connection to Apple which all notifications come over (so I don't believe the number of apps that can push will make much difference).

Incidentally, all those tips you see about quitting applications that you aren't using are nonsense. iOS will only allow them to background for 10 minutes and then only for specific tasks like completing a download. The only exception is playing audio which you want anyhow.

Before the iPhone 5 I had a 4 (not the s). The battery was losing capacity after almost two years of daily cycles. The solution was to pay $9 for a replacement battery on eBay. It came with the tiny screwdriver and there are instructional videos on YouTube. It's easy and cheap to do.

I hope this clears up some mis-information I see around the place. Let me know how you go.

Update

Here's how my phone looks after 27 hours of not being plugged in and normal use for me. That includes quite a few hours of internet and podcast listening but no tethering. If you think you have a problem it would be useful to compare your usage with mine by the time you drop below 20% battery.

Feld Hellschreiber QRP beacon test

Stephen, VK2BLQ, and I continue to experiment with Feld Hellschreiber and I'm pleased to say that next Sunday, November 25th, we'll be presenting to the ARNSW Home Brew group meeting at Dural.

Today I did a test transmission with this little setup:

I've recorded "this is a test transmission from vk2tpm" on a digital recorder which is driving the simple audio keyer to key a two transistor QRP CW transmitter on 7027kHz.

Stephen is about 10km away as the crow flies:

He demodulated me like this:

Not great but amazing considering my transmitter. Come along next Sunday and we'll try to demonstrate across the room.

Red Blue 3D maps from Nokia

I'm a bit of a 3D fan. Nokia has a maps web app at here.net, somewhat like Google and Apple's and it has a unique feature of displaying in red/blue 3D. Here's a shot:

The view is somewhat similar to that which you get from Apple's map, clearly taken from a low flying plane. It's great to see some competition in the maps business.

Pixie 2 based Feld Hellschreiber transceiver

I've figured out that my keying of the CRK-10 CW transceiver is flawed and that I'm not shifting frequency so I've decided to start work on a dedicated Feld Hellschreiber transceiver based on the popular Pixie 2 design.

This clever little design uses the output transistor as a mixer during receive and my modification is to key it with rectified audio from the computer. It's putting out a very pleasing little signal (barely moves a power meter but thats fine for a mode like this) but my audio keying circuit needs work.

Digital QST now available via iPad app

I switched from a paper subscription to the ARRL's QST magazine some months back and have been distressed about the poor experience of having to read it through a terrible web based copy protection scheme.

Just noticed that there is now a QST app for iOS that makes it considerably more pleasant to read.

It's better but still pretty clunky. This feels like the output from some sort of cross platform publishing system. User interface buttons look alien. It surely should be in the Apple Newsstand and should use Apple's subscription system.

QST is laid out for print and it needs to embrace digital publishing by letting us read articles as tall scrollable streams rather than two or three columns of text.

It seems that it's published as images of the page, which makes it big and slow. While there are links, such as from the contents page, there is no text search. (In the end I'll want to search my whole collection for a phrase).

This is a good step in the right direction but it still needs work.

Tiny CW transceiver for Feld Hellschreiber

This morning I had a Feld Hellschreiber contact with Stephen, VK2BLQ on 40m. Here's how he looks to me:

And here's how I look to him:

Comparing the two waterfalls above I think I have too much RF gain which is leading to a noisy receive display.

My goal here is to be able to use a very simple, very small, CW transceiver with a digital mode. Next step is to get an audio driven keyer working.

Update

I've now got this working with the tiny CRK-10 CW transceiver via a simple audio keyer interface.

I'm using a little USB audio adapter and then you can see my simple audio transformer, full wave rectifier and 2N2222a transister to key the CRK-10. In the video below I test transmitting into a dummy load.


Stephen wrote "Good to work you on 40 Hell again.

The CRK10 has a very narrow filter, I was calling you back on 7030 several times, but not until I QSY to 7131.2KHZ that you heard me.

Your RST was about S3-5 but letters were good. Goes to show a microrig and pc  has possibilities.

The narrow filter kills the noise and makes the letters clearer.

I dug out  a couple of older T/R  boxes to mod for keying the tube TX directly. Don't think a relay is fast enough and is noisy. I'll use a powerfet rated for 100v and 1 amp as the Cathode current is 100mA and key up volts is quite high."

Here's how the QSO looked to me:

So aside from the fact that I'm off frequency, my reception is superior to my main rig.

Here is the simple keyer circuit. Small signal diodes, a 2N2222a and a few 0.1uF caps. The transformer is a little audio transformer, not sure what ratio.

I added a 3.5mm socket to the CRK-10 and connected it to the top of C22 where the transistor pulls low to key the carrier.

Thanks again to Stephen, VK2BLQ, for all his help at the other end but it looks to me that a truly minimal Feld Hell transceiver is quite practical.

Digital modes for a CW transceiver

As I don't know morse code and software decoding of morse seems pretty poor in my experience, I've been looking in to digital modes that could be used with a very simple carrier on/off transmitter.

So far, there are two I've found:

• Feldhellschreiber - an on/off fax like transmission of letters using 1ms dots
• CCW - "Coherent CW": an accurately timed version of morse with extra characters supported by MultiPSK. It runs at 12 words per minute and includes a start sequence to allow synchronisation.
• Any others?

There's an informative thread in the Yahoo? digitalradio group.

CRK-10 Tiny 40m CW Transceiver kit review

Just completed construction of a delightful little CW transceiver from Crkits in China.

This US$52 kit comes with all the surface mount components already in place so construction is easy and low stress.

Just two toroids to wind and then only 10 and 12 turns respectively. The kit went together in a relaxed hour or so (I like to take my time and take breaks to try to avoid hard to unsolder mistakes).

The instructions are very clear, all components were there (in fact I scored one extra trim capacitor and a spare screw - much better than being one down). When it all goes together the metal case looks fantastic and it will make a very solid little unit.

The only glitch I found is that the super clear directions on how to wire J1 and J2 for straight key support are reversed. Oddly this error is in both the instruction manual and the quick guide Rev. B.

I also had a bit of trouble with the push button switch's alignment with the front panel hole, reaming it out a little fixed that easily.

Mine puts out a solid 3W and the receiver sounds good and narrow. On the advice of Stephen, VK2BLQ, I ordered mine for 7030kHz.

Now to learn CW.

Update

Adam has confirmed the error, he wrote: "You are correct about J1 and J2 jumpers. It is a mistake and nobody else told me about it. Probably most of them use paddles so they really don't care too much."

It's Microsoft vs. Google while Apple runs free

We're on the eve of Microsoft's launch of Windows 8 and their big new push into tablets. I work with some folks who would have been hard core Windows experts a few years ago but I was surprised to hear them chatting enthusiastically about their Android embedded sticks and hackable low cost tablets from Ainol Novo.

Microsoft's delay in competing with Apple in the consumer tablet market has left the door open for Google to gain huge traction amongst windows geeks with their eminently hackable Android tablets. As Google doesn't make money on Android and Microsoft's business is based on making money from Windows Android tablets will always be cheaper and they are sophisticated enough to fascinate the IT crowd.

Meanwhile, Apple is left to capture the mainstream tablet market while the others fight it out for the geeks.

Microsoft has dropped the ball in recent years but they are doing everything right at the moment, it's just that it might be too late to catch up. If corporate IT departments find that their users have Android or Apple tablets and phones they may start to move off Exchange and that will leave Microsoft out of the picture.

Bargain 12V 32A HP PS-3381-1C1 Power Supply pin out

At the last trash and treasure at Dural I was lucky enough to be steered to a bargain at $10 each. There was a pile of switching power supplies that are known for the low RF noise. HP PS-3381-1C1s.

When you power them up the +12V rail isn't active and a few jumpers are needed to get this going. I found the necessary wiring in a radio control group so I guess these supplies are also used for charging big batteries. Here's the three jumpers to earth I added to get it started:

And here's the 12V out at up to 32A (although I'm not sure my wiring would cope with that for long).

The fan isn't too bad, particularly given the high current capacity. Mine outputs 12.3V but I understand there are modifications for pushing that up to 13.8V to get the most out of some transmitters.

British spy "paraset" transceiver duplicate

Today at the ARNSW Home Brew group meeting we had a terrific presentation about the world war two "spy set" transceiver which was given out to resistance forces in Europe. There is a popular construction project that aims to build a pretty accurate replica.

Peter Jensen, VK2AQJ, has done a wonderful job of re-creating one of the versions of the set and in tracing the history of these interesting rigs. The simple design uses three metal valves and the receiver covers about 3.2 to 8MHz.

Peter is a wonderful speaker and I understand has published at least one book which I'll track down.

I bought a little bit of junk for the shed today although there is lots to temp me in the Dural disposals room.

Thanks as always to the organisers and it was great to have Mal, VK2BMS, along for the day.

iPhone 5 LTE speed test - better than home cable

Rather than queuing on Friday, I simply wandered in to a Telstra store at Warringah Mall on Saturday at about 10am and got an iPhone 5 within minutes. Very smooth. This morning I checked my home Cable speed test and then on arrival in the Sydney CBD checked Telstra's LTE performance:

That's 24.39Mbps down and 23.36Mbps up. Really impressed apart from ping but even that isn't bad. More than enough people have reviewed the phone and I'm very happy with it so far too.

Update

It's amazing what LTE can do if you're the only user, check this out from a Brisbane tester reporting on Whirlpool.

87Mbps! But faster than 99% of AU tells the true story.

Swipe 2012 iOS developer conference in Sydney

This week I was lucky enough to attend the "Swipe" conference here in Sydney.

The highlight for me was the keynote presentation by Horace Dediu who I listen to on the "Critical Path" 5by5 podcast. The image above shows revenue from digital music sales compared to revenue from app sales, the interesting thing is that apps are now a bigger business than music.

Horace took us through the history of personal computing by using animated graphs showing the rise and fall of different products and brands. The stand out is that tablets have taken off faster than any product before them. While traditional "big screen" personal computers continue to experience some growth it is fairly flat compared to new devices such as smart phones and tablets.

The iPad is particularly profitable and in fact the iPad alone is worth more than the entire PC business. Microsoft's revenue for operating systems is rapidly declining. Android and IOS have completely re-defined what growth can be.

I asked Horace why, if Android is the number one platform, does iOS still see 70% of the internet traffic? He said it's about engagement. Android users wanted a smart phone or tablet but what you can do with it is less "discoverable" and this is a problem for customer loyalty. Many Android buyers bought a smart phone but they're using it as a feature phone.

Other highlights were the "ABC Art Maker" case study from Amy Nelson and Meena Tharmarajah, "iOS Performance Tuning" from Bill Dudney, "Designing Accessible iOS Apps" from Jake MacMullin, "Blocks and Block based APIs" from Cameron Barrie, "Australia Post case study" with Chris Van Raay, and "Automated testing with KIF" with Chaise Hocking.

My compliments to the organisers and I look forward to the next conference.

A look inside ABC News Radio

In contrast to the display of historical radio equipment in the foyer, I was privileged to get a personal tour of the ABC News Radio operation today. It's a very striking layout that appears to genuinely (almost) paperless.

Journalists and producers surround and face in to a "fish bowl" style studio.

 News Radio is transmitted on over 60 frequencies and reaches a million listeners each week.

Inside the studio it's a one person operation with the presenter who controls everything and reads directly off screen.

Thanks to on-air announcer Steve Chase, and everyone who cheerfully greeted a regular listener and fan. Sometimes seeing a radio station and the staff breaks the magic, in this case it's the opposite - I came away more impressed with the efficient and well designed News Radio operation.