Tuesday, July 09, 2013

Tour of the Marconi Museum near Bologna

The reason we chose to come to Bologna is to take a tour of the museum at the house where radio pioneer, Guglielmo Marconi spent his childhood and did his initial experiments with electricity and, most famously, increasing the distance of radio transmission. Villa Griffone is an imposing building.


And here's the view back towards the highway.


To get there we caught the Number 92 blue bus from Bologna, it was €7 return for both of us and the trip took about an hour (but it might be quicker with less traffic).

You can clearly see the house from the bus but there's trees before and after so I'd ask the bus driver to warn you as it approaches. The stop is about two stops past the centre of Borgonouo.

You need to book a tour to visit, it's just €5 per person but it's well worth while. Here's some photos which were highlights for me, but there's lots there besides this.

 Marconi improved on the distance that spark transmitters could be detected in several ways. On the left you can see the equipment with an antenna above and earth plate below.

We now know that these are much too small for the long wavelengths he was probably dealing with but anything was an improvement.

In particular, Marconi improved the "coherer" as detectors were known in those days, he added a little hammer that re-scrambled the metal filings in the tube that helped them to stay highly sensitive to electric fields.

A coherer, a tube of metal filings, used to detect radio frequency signals.


Here's a reproduction of Marconi equipment that would have been using on board a ship. 


A beautiful reproduction spark gap device.


This next one was new to me, it's a detector that uses magnetic hysteresis in iron to detect radio signals. To operate it an iron wire must be drawn through concentric coils, one has the antenna connected to it and the other goes to an amplifier for the detected signal.


There is a fully working spark gap transmitter and receiver setup too, imagine the interference this would cause!




And here is the receiver:


There's lots of interesting gear on show, while not part of the Marconi legacy, this was the first time I'd seen a feld hellschreiber machine in person. (A clever German device that sent a kind of fax of a line of text via simple on-off keying).


Here's an early Motorolla hand held transceiver with my phone next to it.


Interior of the Motorolla transceiver showing the compact valve construction.


This interesting display let us compare different types of rock for their semi-conductor abilities for use as a diode detector.


In one of the pine trees near the house, original antenna wire from a young Marconi was recently recovered.


Marconi's upstairs workshop with the kind of equipment he used. The museum has reproduced many of his instruments and actual working models of experiments for the display.


This is the original of the iron hysteresis detector built in a cigar box by the looks of it.



We were very lucky to have Marconi scholar Barbara Valotti as our guide. She has been researching early Marconi notebooks and helping to re-write the somewhat distorted history of the man who is often portrayed as a lone genius who had flashes of inspiration rather than a methodical self-taught scientist who experimented over many years to develop technologies that could be commercially exploited.


Although we came to Bologna to visit the Marconi Museum, I would add that we've found it a wonderful city to visit. The people are much more friendly than at the tourist locations elsewhere and despite my embarrassing lack of Italian everyone has been helpful and understanding.

I'd highly recommend a visit. My thanks to G4FTC who's web site tipped me off to this great attraction.

Thursday, July 04, 2013

Galileo Museum in Florence

Normally I like to look at shoes and handbags but my wife insisted on some science content for our current tour.

Galileo Galilei lived until 1642 and was revolutionary in terms of evidence based knowledge in an era when the church laid down physical laws without question. Here's a machine that explains the (extremely complex) mechanism by which the earth could be at the centre of the universe.


Galileo used, and improved the telescopes of the time to make his own observations and came up with conclusions at odds with conventional wisdom.



In the 1600s, 1700s and 1800s it seems that science was a very popular topic and demonstrations of phenomena which were not well understood, like atmospheric pressure, electrical charge and momentum were a common parlour trick to entertain the rich. Some wonderful devices, beautifully crafted in wood and brass survive and are on display in the museum.

An electrostatic generator:


Glass rubbing electrostatic generator:


Vacuum pump:


Lens grinding machine:


Even an executive toy:


Galileo was tried by the Catholic church and found guilty of heresy. He was tortured and forced to agree that the sun went around the earth, although it's said that under his breath he said that it wasn't true on the way out. He lived under house arrest for the remainder of his life.

In October 1992, Pope John Paul II expressed regret at his treatment, so I guess we can look forward to apologies for contemporary crimes in just a few centuries.

Wednesday, July 03, 2013

Travel has changed in 25 years

Twenty five years ago, Phillipa and I travelled to Europe together. We booked through a travel agent who suggested accommodation that met our budget - mostly "pensiones" as I recall.

I was always suspicious that the travel agents would recommend places with the best kick-backs.

In Florence I proposed that we marry and a quarter of a century, and two adult children later, we're back, but a few things have changed...

This time we booked with Airbnb where individuals rent out their apartments and are reviewed by clients. By the same token, clients are reviewed by hosts. We've paid as little as AU$80 a night for a complete flat which suits us just fine - it's great to be able to be able to make our own breakfast and do washing.

Technology has changed too. Last time I was here everyone had film cameras, now it's digital and there's a lot of people shooting on smartphones and sharing on Facebook. One of the key review points for a flat is the quality of the included internet and wifi - so far it's been pretty good (but not as good as at home).

The other fun toy is using a Fitbit dongle to count steps. On holiday, I do quite a lot of walking and am hitting up to 20,000 steps in an active day.

While free Wifi is quite common you have to seek it out and often it has annoying terms and conditions to agree to. In each new country I receive a string of scary messages from Telstra warning me about high roaming fees. Surely the cost is just a transaction fee which should tend towards zero. Is mobile data really a scarce resource? I think travellers are being exploited deliberately.

My strategy has been to purchase pre-paid global roaming data and to enable roaming data just when I specifically want to look something up - like on a map.

I'm also using off line maps from CityMaps2Go and travel info from Triposo.

There are commercial Wifi services too, I purchased a month of boingo but have not found it useful - the only place if offered service had 45 minutes free anyhow.


$15.36/MB, really! How on earth can that be justified? I do like the warnings but as I have purchased an international data pack it would be good to be aware of that.

Sunday, June 23, 2013

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.

Friday, June 21, 2013

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).

Saturday, June 15, 2013

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).

Wednesday, June 05, 2013

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.

Monday, June 03, 2013

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!

Sunday, June 02, 2013

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.

Saturday, June 01, 2013

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.


Sunday, May 26, 2013

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.

Saturday, May 25, 2013

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.

Wednesday, May 22, 2013

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.

Tuesday, May 21, 2013

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.

Saturday, May 18, 2013

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.

Monday, May 13, 2013

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...

Sunday, May 05, 2013

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.

Saturday, May 04, 2013

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.