Knobless Wonder build

Over the past few weekends I've been building VK3YE's "Knobless wonder" a fixed frequency SSB transceiver for 40m. It's at the point of starting to work, although transmit sound is very poor right now.

A scan of the circuit is here. I've enjoyed the build, it's simple enough for me and I was careful to build and test stage by stage, stopping if something didn't work and figuring it out before going on. The main thing that goes wrong for me, aside from failure to follow the circuit accurately, is that sometimes I have mis-filed components that I grab without checking.

The technique I've used is "Manhattan" ugly construction using snap off squares I purchased on-line and super-glued to the base boards. This turns out pretty neatly and makes the board look like the circuit diagram so it's easy to debug.

So far the receiver seems pretty deaf, although it hears my shack oscillator sweeping quite well. The transmitter has been heard by VK2BMS a few Km away although the audio is not good at this stage. I think the oscillator isn't tuned correctly yet - I need to figure out the best way to adjust this.

My thanks to Peter for a nice design that is easy to reproduce. I think this is a great group project for people who live pretty close together.

Updated ABC rage app in the Australian app store

It's been a great pleasure working with the ABC TV rage team, a wonderful graphic designer and producers to do an update of the popular rage app.

The design is pretty wild but from a software developer's perspective I've focussed on minimising internet traffic by doing HEAD requests and only pulling down playlist data, artist images and bios as required.

Playlists are cached in a local core data store so that opening the app is fast and memory use is minimised.

It's amazing that this TV show has been on air since 1987.

Please check out the app and if you like it, give us a rating and review. (If you don't like it, I hope you'll contact us).

Raspberry Pi as an OpenVPN server

Many of us work inside fire walled networks where virtually all ports are blocked and web traffic goes through an annoying proxy server. A VPN connection makes your computer appear to be on another network and these issues go away.

Another big reason to operate through a VPN is if you are on someone else's network, perhaps a cafe Wifi service, and are (rightly) concerned about your traffic being snooped.

There are commercial VPN services available but I've recently set up a raspberry pi as a server and it works really well sitting on my home internet connection.

OpenVPN requires a single port, either TCP or UDP, between client and server.

Installation is well documented in several places, but I referred to the excellent instructions on Remi Bergsma's Blog.

I made two changes:

• Used tcp rather than udp as for some reason I couldn't connect via udp - update the setting in /etc/openvpn/server.conf
• Enabled nat on the pi as I was unable to set a static route on my home router - an Apple Airport extreme.

The command to enable nat on the pi is:

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

I added that to /etc/rc.local so it will be re-applied on each boot.

Finally I forwarded the TCP port I want to use to connect from my home router to the Raspberry Pi. My home internet connection occasionally changes public IP address so if that becomes a problem I might use a dynamic DNS service to keep track of it.

Client

I use MacOS mostly and I'm using the Viscosity client which has a 30 trial period (which I'm still in) and then costs just US$9 which is very reasonable. At first I tried the free Tunnelblick client but it doesn't quite work at the moment with Mountain Lion (I can't get it to correctly set the DNS to the remote end of the tunnel).

Digital data transmission tests on Radio Australia

Please be advised of the second Radio Australia HF test using the digital text modes MFSK and FLARQ.  Freeware fldigi will handle these automatically - see http://voaradiogram.net/   and http://www.w1hkj.com/

The text will contain text and images from Radio Australia's web site as well as contact details for sending responses. Note 2150 UT Sunday is Monday morning 0750 EST in Melbourne etc.

All dates/times are in UT, all frequencies in kHz
Saturday/Sunday 8/9 June 2013

0850-0857 UT on

 7410 (PNG & south-west Pacific)


11945 (south Pacific, NZ, central America, Europe)

1230-1237 UT on

 6080 (PNG, west Pacific, Philippines, Japan),  new freq for MFSK

 9580 (central Pacific, NAM)

12065 (central Pacific, NAM)

2150-2157 UT on

11695 (south-east Asia, Europe)  new freq for MFSK

21740  (central Pacific, NAm)   new freq for MFSK

with 40s of RA tuning signal (Waltzing Matilda) at the start of each session.

Extremely poor reception here this morning of 11695. I could barely detect that there was a station there and only a few words were decoded.

Update

The tests have been a success and reports are coming in from around the globe. The Voice of America's Dr Kim Elliot, reports on his reception in Northern Virginia where despite poor audio reception, the digital text message was perfect.

Knobless Wonder 40m SSB QRP circuit from VK3YE

Peter, VK3YE, recently showed me a new home brew fixed frequency single sideband rig he dubbed the "knobless wonder". I think this is a great group project where the fact that it's fixed frequency is an advantage in encouraging contacts between builders.

He's given permission for the circuit to be published here (click to enlarge).

I highly recommend Peter's walkthrough video complete with a series of contacts on the actual rig.




Thanks Peter!

Tune in to "Download this show" tonight

If you are near a radio this evening, tune in to ABC Radio National where I join host Marc Fennel and co-guest Claire Porter (from news.com.au) to chat about human technology matches and mis-matches.

Can't tune in? guess what, you can download this show or subscribe to the podcast by searching for it in your podcast app or iTunes.

Always a pleasure to join Marc and other guests on my beloved Radio National.

Tablet friendly M65 Jacket - as seen on TV

You don't get much fashion advice on this blog, until now. If the M65 field jacket seems familiar, it's because Robert De Niro wore one in Taxi Driver, Al Pacino wore one in Serpico, Sylvester Stallone wore one in multiple movies and Arnold Schwarzenegger wore a decorated one in Terminator. And that's just the start, check Wikipedia for about 40 references.

Introduced into the US military in 1965 to replace the M51 which replaced the M43 (you can figure the years).

The exterior is poly cotton mix, there is a 100% cotton lining and a further, buttoned on detachable inner warm layer. The instructions warn not to dry it on a stove, so I guess that was a problem.

What's amazing is that in 1965 they correctly predicted the dimensions of the now popular seven inch tablets and a Nexus 7 fits nicely in the side pockets. Great forethought there. Available at army disposals stores globally.

First test with cheap $5 AD9850 DDS board and Arduino

News of the availability of very low cost AD9850 DDS boards from China via eBay has swept the home brew radio community in recent weeks. These chips alone were quite expensive and the surface mount soldering was a challenge.

Now the chip, mounted on a nice carrier board, with 125MHz crystal, is available for a very reasonable price. Here's mine sweeping a few frequencies near 10MHz:


The Arduino code I used is from NR80 which in turn is based on code from Andrew Smallbone.

I simply powered mine from the 5V on the Arduino and it seems to work just fine.

Our plan is to make a little crystal replacement board for QRP purposes with a multi-position switch to select the frequency.

Purchased a blank Arduino shield board and have now mounted the DDS board nicely for future software development.

Melbourne meetup with homebrew legend VK3YE

While in Melbourne for the fabulous "One More Thing" conference this weekend I had the pleasure of breakfast with ham radio home brew legend Peter Parker, VK3YE.

Gracious with his time, Peter brought along a number of recent projects including the famous "Beach 40" and a new fixed frequency SSB transceiver he dubbed the "knobless wonder" that has been recently completed.

Peter works in the public transport industry, (may I say how impressed I am with the Melbourne MyKi system), his knowledge of the network is impressive.

We talked of many things including cross-overs between amateur radio and public transport including Tony Sanderson, VK3AML, and the videos made by Dave VK3ASE of the Glenhuntly station crossing.

Peter is a self-taught radio electronics engineer who is performing a great service to all would-be home brew designers.

Here's some previews of the "Knobless Wonder":

Nice crystal filter array there.

Here's the popular Beach 40:

Thanks Peter for your time and generousity. Keep up the great work!

Update

Thanks to Bill of Soldersmoke for the mention.

Good news: Peter has updated the Knobless Wonder circuit and published a video here:



The circuit is here.

A wonderful One more thing conference

Really enjoyed "One more thing" again this year in Melbourne and at the pub afterwards ran in to Luke Anear who pulled out a Google Glass device much to my amazement.

I put on the Google Glass headset and found the display incredibly clear. Despite the noisy pub environment, even with a band playing the speech recognition worked very well.

After returning to Sydney I introduced Luke to Marc Fennel who followed up with a great video story about Glass on SBS2's The Feed.

Looking forward to One More Thing...

On Friday I'm off to the "one more thing" iOS developer conference in Melbourne. Last year was great. At the time I was only a part time iOS developer, now it's 24/7.

Developing apps for smartphones, more than any other software I've worked on, is a team effort where programmers work closely with designers. I love the way we iterate and what is only learned by playing with the app as it comes together.

The phrase "one more thing" references something that Steve Jobs used to do sometimes at, what seemed like, the end of a keynote speech where he would reveal something amazing. Past "things" have been the MacBook Air, Apple TV, Powermac and Airport.

WWDC is a few weeks away and there is much discussion in my office about what Apple might announce to fill the product void that has opened up since the iPad Mini last year. We can be confident that pretty much all laptops will be refreshed with the new Intel Haswell chipsets, we can hope that a new MacPro line will begin and that HiDPI (Retina) screens will come to the desktop.

I think there are some important technology transitions taking place that Apple has chosen to wait for rather than bring out products that will be vastly superseded in a few months: Thunderbolt - which is jumping in bandwidth to 20Gbps, presumably enough for 4K video, plus the ability to put cards - such as video cards, in the monitor; Intel's new generation of CPUs that reportedly will use 1/5th of the power of the previous generation in laptops, and large high resolution displays which will have taken time to come down in price.

On the software side, I can't wait to see what's in MacOS X 10.9, Xcode, and of course iOS 7 under new management.

While it might be nostalgic to hear Tim Cook say "one more thing", perhaps it best left to a bunch of us in Melbourne this Friday.

MacOS X Calendar knows time zones!

Just discovered a great feature of Apple's Calendar application - you can add an appointment with a time in another time zone and it converts to local for you. Create a quick event with a time zone:

And it gets added to your calendar in local time:

I can't tell you how many times I've messed around figuring out when a keynote will be in local time.

Apple software often looks simple, but is really deep.

Radio Australia Digital Test

In this age of information over the internet, the role of short wave broadcasting is being questioned. We thought that the internet would kill off Amateur Radio but instead low cost computers have led to an explosion of interest in digital modes over HF.

Countries that wish to prevent their citizens from reading news from external points of view are able to easily filter or even turn off the internet and while they can jam short wave radio, it turns out that digital modes can get through when voice would not.

VOA has been doing tests in recent months and tonight Radio Australia did their own test on 7.410 MHz at 6:30pm Australian Eastern Time and here in Sydney I received it perfectly.

I decoded with fldigi:

As you can see, decode is perfect.




And here's reception from Colombia:



Here's my reception on Sunday night:



I remember as a teenager decoding RTTY news broadcasts which used to be a regular feature of shortwave, perhaps it's time for a new era of digital news over short wave taking advantage of robust new modes and widely available decoding software?

Information about similar tests in the future can be found via the VOA Radiogram blog.

Beaglebone black first impressions on MacOS

I'm a bit of a sucker for a cheap unix computer. In recent months I've been playing with Raspberry Pi devices but ran in to problems with audio over the USB. When the $60 Beaglebone black went on sale, I couldn't resist.

This board, which is about the size of an Altoids tin, features:

• 1GHz ARM Cortex-A8 processor
• uHDMI video socket
• uSD card socket
• 2GB on-board storage all ready to boot
• 5V in socket
• 2 USB sockets
• Ethernet socket

To get started, I've done the following:

• Plug the board in to the USB port on my Mac using the supplied cable (no other power is needed for the board)
• A USB storage device mounts and all the documentation and drivers are available. Open START.htm to read the documentation.
• From the Drivers folder, there are two drivers, one for serial over USB and the other for a network connection over USB. I already have the serial FTDI driver so I installed the RNDIS driver (which seems to be an Android open source thing).
• Unmounted the BEAGLEBONE disk, unplugged it from USB.
• Re-plugged the USB and waited for the drive to mount.
• At this point I could ping 192.168.7.2 and load http://192.168.7.2
• In terminal ssh root@192.168.7.2 (hit return for password)
• Plugged the board into a hub on my network with an ethernet cable
• ifconfig shows that the board now has an IP address and can reach the internet
• opkg update
• opkg upgrade # this runs for some time (I left it over night)

It's marvellous that the board has enough storage on-board to boot up linux and there is a socket for extra storage. Angstrom linux is a mystery to me but I'm going to give it a go and maybe switch to something more familiar to me later if I hit a wall.

Later...

Hmm, I left the opkg upgrade running over night but in the morning I notice that it didn't complete correctly - looks like it lost network connection.


 * opkg_install_pkg: Failed to download perl-module-unicode-collate-locale-da. Perhaps you need to run 'opkg update'?
 * pkg_run_script: package "bonescript" postinst script returned status 1.
 * opkg_configure: bonescript.postinst returned 1.
root@beaglebone:~# reboot

It did not reboot. I've tried with the ethernet cable disconnected (a user reported this as a possible issue). I have to go to the office so will come back to this and report when I figure out how to re-flash.

Today, I picked up a 4GB uSD card and followed the instructions here to re-flash the built-in on-board flash and all is well.

MacOS

The provided instructions are rather focussed on Windows for imaging a uSD card for re-flashing but I was able to do it on MacOS as follows:

Use 'diskutil list' before and after inserting the card to figure out which /dev/diskX it is.


$ diskutil unmountDisk /dev/disk2
Unmount of all volumes on disk2 was successful
$ sudo dd if=BBB-eMMC-flasher-2013.05.08.img of=/dev/disk2
Password:
7143424+0 records in
7143424+0 records out
3657433088 bytes transferred in 12416.160438 secs (294570 bytes/sec)

It's rather slow, this took 3.5 hours.

I like the way the default linux registers the beaglebone on mDNS (bonjour) so I can find it on the network like this:

ssh root@beaglebone.local

Incidentally, these things really do fit in a lolly tin, here's mine in a "Fisherman's Friend" tin along side a Raspberry Pi.

Resources

There is a big list of projects.  Angstrom Linux has a marvellous list of pre-built packages. I notice that gnu-radio is there...

PA0RDT Mini-Whip E-Field antenna

A recent presentation at the WIANSW Home Brew group about receiving on the 630m band mentioned that a very small E-Field antenna works almost as well as a full size antenna at these very low frequencies.

I wrote off to Roelof Bakker and ordered his pre-built "Mini Whip" antenna (plus another for local ham James, VK2JN). The circuit is very simple and Roelof has published it but I decided to go with his selected parts and weather proof construction on this occasion.

A few weeks later and the antennas arrived. Construction of the external probe part and also the power injection box are both very solid. BNC connectors are used everywhere.

The antenna came with a "9V" out 230V plug pack with european round prongs.

This is an active antenna with a small area of copper for receiving that should be mounted a bit above roof line on an insulating pole. Power is sent up the co-ax and is injected with a little box in the shack.

At first I had trouble - it turned out that there is water in my co-ax and the 15V inserted in the shack was just 3V at the antenna! (Amazingly I've been having WSPR contacts on 20m for months with this arrangement).

I find that the PA0RDT Mini Whip works best at 40m and lower frequencies. It's not quite as good as a full size dipole but has the benefit of being broad band. Here's a video of the parts and a bit of local reception on 40m.


If you don't have room for a full size antenna and are interested in lower bands I can recommend one of these active antennas.

Here's how I receive Ross, VK1UN who is about 750km away on 80m WSPR:

Given the tiny size of this antenna, it's amazing to receive anything at all on 80m in a suburban house.

Wearable computers for health

Inspired by colleague Jason Crane, I've started wearing a little clip-on bluetooth connected dongle from Fitbit.

The device itself is quite small and I barely notice it clipped to my shirt - how long until it goes through the washing machine?

It records how many steps I walk each day plus how many floors up climbed. If you wear it at night (they have a wrist strap that makes it comfortable) it records how "efficiently" I sleep.

The device stores data until synced over bluetooth 4 (very low power) using an app - I'm using the iPhone app which is good but crashes rather a lot at the time of writing.

The app uploads the recorded activity to a web site where it can be graphed in even more ways than in the iPhone app, plus you can friend people and enter in to a bit of friendly competition.

The scary thing is how much of my day is spent totally idle sitting in a chair staring at a computer screen.

I am over weight although thankfully not "obese" at this stage. Wearing the tracker does motivate me to climb the stairs where possible and walk to the shops on the weekends.

Bluetooth 4 is a good technology. The device lasts all week even though it's listening for a connection from the phone app at all times.

This week I purchased the Fitbit scales. They connect to the home Wifi network and by simply standing on them it measures my weight and uploads it to the site. The most impressive bit (for me) was how it was configured and given the details of my Wifi network by running an app on my computer. I'm not quite sure how this was achieved as clearly scales don't have much of an input device.

Of course Fitbit isn't the only game in town, there's Nike, Jawbone, Basis, Striiv, Larklife and many others.

All this current interest in wearable computing, like Google Glass and the rumoured Apple watch, are good things if they help us to avoid turning into the blobs like in the Pixar Wall-E movie. Computers have freed us from physical activity, now hopefully they can help us stay active enough to live.

WSPR Watch for iPhone updated

I'm pleased to announce that a new version of the iPhone App "WSPR Watch" is now available in the App store.

New features are:

• Sort spots by Time, distance, SNR and Km/W
• Show only recent spots from 2 hours, 1 hour, 30 mins or 15 mins
• 600m band

Plus there's some cosmetic and operational improvements. WSPR Watch is free and pulls its data from the old database page of WSPRnet.org (thanks to those folks!).

Thanks to Will and Ross for suggestions and testing.

iOS seems to download files over Wifi 3.5x slower than Android

I hope I'm mistaken about this but my experiments seem to suggest that iOS downloads large files significantly slower than an Android device on the same Wifi network.

For the test I download a 70MB test jpeg file in the Chrome browser on both an iPad Mini running 6.1.3 and a Nexus 7 running 4.2.2. The Wifi network is an Apple Airport Express running 7.6.3.


Android downloads the file in 91 seconds,  iOS takes 314 seconds.

I forgot to show it in this video, but the Android version is really there at full resolution if you tap on it.

I've repeated this test using Safari on iOS and it's the same so I think it's something to do with Wifi or the TCP stack.

Has anyone else noticed this?

Fibre to the premises or to the node?

The complex and expensive national infrastructure project to create a National Broadband Network in Australia is underway. Not surprisingly it is taking longer and costing more than initially hoped and now the opposition is proposing to cut costs by cutting an important corner.

Rather than doing the hard part, taking optical fibre to each home, they propose to run fibre to nodes and re-use existing copper to get to houses. This approach will deliver an improved internet at a lower cost but both only in the short term.

To me, it's like building a highway system with dirt road off-ramps.

Looking back at the history of internet speeds it's clear that speeds grow logarithmically and there is not sign that this will slow or stop. It's inevitable that the last mile of copper will be a choke point and a future government will have to come back and finish the job.

ABC Radio National Breakfast aired interviews with me and finance correspondent Sheryle Bagwell where we looked, in turn, at the technical and financial analysis of the alternate plans.

As I said in the interview, this is not really about politics, it's about the relentless march of technology.

630m operation and Class E at Home Brew Group

Two excellent talks at the ARNSW Home Brew Group meeting today. The main talk was by Nick, VK2DX, who talked about getting on the 630 meter band (472-479kHz).

Nick talked about his long history of listening to interesting things he's seen on the waterfall including over the horizon radar and non directional beacons. Getting on air with such a low frequency is a challenge anywhere but particularly in a dense metropolitan area.

The challenge is the antenna and matching to it. Ironically, while the best antenna is something huge like a beverage antenna, the second best is a tiny E-Field probe like the PA0RDT mini whips.

Nick uses a vertical antenna that is resonant on 80m but with the addition of a huge 600uH loading coil (60 turns on a bucket), a home built variometer and an impudence matching transformer he's getting to QLD, SA and NZ using the WSPR mode.

The supporting talk was my regular Mike, VK2BMR who talked about his experiments making a tesla generator operating in class E.

Mike is getting great efficiency, which is the great benefit of Class E, and his biggest challenge seems to have been to build attenuators and dummy loads that can handle the power he's generating. I was hoping for a demonstration with a bit of indoor lightning but maybe next time.

As always, thanks to the organisers for another great day at Dural.