Monday, September 30, 2013

ARNSW Home Brew 40m antenna day

A beautiful day to be out doors in Sydney's Dural on Sunday. The theme was 40m antennas and there was lots of great talk, show and practical setting up of different antennas. A slinky antenna looks like a good idea but this one was too tangled to put up.

Stephen, VK2BLQ, had a big collection which began with the Ozi-pole short dipole for 40,20,10 and 6m.

Then a broadband end fed long wire the Ozi-Wire:

Peter Parker's end fed trap for 40 & 20m:

Outside antennas were put up using a variety of means, including a bow and arrow:

A telescopic flag pole (very patriotic):

There was a shortened vertical by Peter VK2EMU, here inspected by Mal, VK2BMS:

An impressive 40m quarter wave vertical seemed to perform well:

The stand-out for me was Owen's marvellous end fed half wave tuners, this one with a variometer, here being tuned by John VK2ASU:

An interesting comment was made about following detailed antenna instructions from Europe and the U.S. in that antennas perform differently here in Australia because our earth is much less conductive.

Ironically, antennas in Australia perform better when put up at night, when it's raining. There's a thought..

Sunday, September 29, 2013

Tune in to popular Downloadthisshow Sunday at 9pm

Downloadthisshow, a weekly panel and interview show by Marc Fennel, now has more than 300,000 subscribers on SoundCloud. Add that to subscribers on the iTunes podcast and of course radio listeners on ABC Radio National, some local stations and Radio Australia, and it's an amazing audience built by one talented and hard working producer, presenter and editor, Marc Fennell:

Maybe people are just following the oh, so subtle, command embedded in the program title?

This week, with co-panelist Karalee Evans, we chat about ads on Instagram, buying emerging art from Artsicle, and we play with the hand tracking Leap Motion.

While space wars might seem like a fun application for the Leap motion:

In the show you'll hear that I have a much more down to earth idea for the technology. RN, Sunday at 9pm.

Hornsby Ku-ring-gai fire control centre

Saturday was open day at the state of the art Hornsby Ku-ring-gai Fire Control Centre used by the Rural Fire Service to support local volunteer fire crews. It's an impressive communications and incident management setup.

The tour I had was hosted by Peter, VK2GPH and Leah, VK2FREE (great call sign!).

Originally the plan was to have a barbecue but ironically it was a "TFB" day and I had to bring cheese sandwiches instead.

Monday, September 23, 2013

Low cost vertical laptop stand from wood desk easel

Retina MacBook Pro screens are so sharp it's crazy not to use them as the primary screen when working at a desk.

Presumably Apple will introduce a range of retina desktop screens sometime soon (October anyone?), but until then I had a great idea for how to prop up my office laptop in a near vertical position while still being quite stable.

The trick is to use a little wooden desktop easel available for under $30 from art shops. At left is the one I bought and below is how my desk now look at the office. It's adjustable and has a nice pine wood smell and all. I've seen other stands at stationery stores and they are expensive and cheap plastic construction.

Here's how my desk looks now. (I do have an external screen on the right for running the iOS simulator and viewing documentation).

Saturday, September 21, 2013

iOS 7 adoption soon to exceed iOS 6

After only a few days, my apps are starting to show the amazing uptake of iOS 7. Here's my proportions in WSPR Watch from yesterday.

39.2% iOS 7.0 compared to 40.5% iOS 6.1.3 plus 7.6% for iOS 6.1.4.

iOS 7 seems a bit rough at this point so I can only assume they rushed it out to be able to launch with the new iPhones last week. I'm sure there will be some updates in the weeks ahead. Having said that - it's fine for daily use and a refreshing change.

Update a day later. iOS 7 is still growing fast.

Note that Google Analytics swapped the colours around. iOS 7 is now at 50.8% which exceeds the total for iOS 6 for my app.

Friday, September 20, 2013

Queuing for an iPhone 5s in Sydney - human nature on display

Even though I generally have no trouble picking up a new Apple product soon after launch, I decided to get up early and queue outside the Sydney George Street store this morning. It was an interesting experience.

Oddly, the crowd was overwhelmingly of Asian origin.

I arrived at 6:15am and there were hundreds already lined up around the block and down York Street. The woman in front of me was from Thailand, and behind me were a group of ten from Vietnam.

Without exception, everyone I spoke to wanted a gold iPhone 5s (clearly Apple has missed a key desire in the Asian market until this year). Many were in the queue to buy stock to resell at a profit in countries where the launch will not be for some time.

The group of ten from Vietnam were a "team" that planned to buy the maximum and then go back and re-join the queue. That means two 5s and ten 5c phones that would leave on a flight later in the day.

Given the long time involved (I joined at 6:15 and got to the store at about 10:00) a major annoyance was people surreptitiously jumping the queue. I saw a couple join in a driveway gap, they played dumb and said they thought that was the end of the queue, hmm. Without too much prodding they backed off and left.

Another pair kind of stood beside the queue for a while in front of the woman in front of me and then started walking with the queue until they gradually merged in. The woman was annoyed but didn't say anything - I was not so easy going.

I told them they could not just join a queue hundreds of people in - the main chap looked me in the eye and said he'd been there all morning "since 4:30am". I said that was nonsense. Next he claimed to be with a guy in front - I tapped him on the shoulder and asked to confirm the connection, there was none.

What I found amazing is that this guy was calm and while behaving in a rather vague way was able to look me in the eye and lie repeatedly. I called the security guards and they agreed that these interlopers had pushed in. The guards assured them that even if they stayed in the queue they would not get a phone. Even so, the queue jumpers remained in place for some time. They asserted that the guards would soon forget and all would be well.

I asked how they could lie so blazingly, they explained that everyone is like that. In the end they did give up and we reached the door of the shop.

Overall the mood was good, with lots of chat and good organisation from the Apple store staff on hand. I do feel manipulated though, Apple took a lot of time to process orders - offering a full service including SIM swaps, carrier plan activation and data migration. Many customers, like me, just wanted to purchase outright and could be in and out in a minute, but we had to wait.

The queue attracted the normal media attention with TV stations, plus a helicopter and I was briefly interviewed by @ClaireRPorter of News Ltd (until she figured out that we've met as fellow commentators).

The iPhone 5s is great by the way, the Touch ID fingerprint unlock is a truly differentiating feature that will lead me to use the phone much more than in the past. The other great unexpected feature, at least in Australia is the amazing tiny charger:

Oh and the 64bit processor and M7 motion chip which will hopefully replace the need to carry a FitBit dongle.

Gold 16GB and later 32GB phones sold out first, the same story was reported at Broadway which I visited at lunch time. They said they had "plenty" of the lower priced 5c phones.

I can see why Apple is not too concerned about going "cheap", even when they do the high end phone seems to sell more - at least near launch. Time will tell but I think the colour phones will be the big seller in the months ahead.

Next time, I'll skip the queue, but it was an entertaining experience.

Monday, September 09, 2013

Chinese HF transceiver X1M initial impressions

Just arrived in the shack is a very compact 4.5W all band SSB HF transceiver of Chinese origin. With a price of US$350 + shipping and an all surface mount (except the final) construction it was hard to resist. Here it is next to my trusty Yaesu FT-817:

While construction is a little "home brew" by comparison to the Yaesu, the X1M has a very informative display that is easier to read than the '817. The buttons are pretty flimsy but ok and the volume and tuning knob are basic but will do the job. Here's the top view:

This is a very solid feeling, compact rig that runs on 9.6 - 14.5 Volts DC and will be terrific for portable QRP operation drawing 500mA on receive. The receiver is quoted as being better than 0.45uV and the pre-amp seems to make a huge difference.

Received audio is strong (the Elecraft KX3 could learn from this rig!) but bandwidth is fixed.

Receive: 0.1 - 30MHz continuous.


Band 1 3.5 – 4.0 MHz (80 Meters)
Band 2 7.0 – 7.3 MHz (40 Meters)
Band 3 14.0 – 14.35 MHz (20 Meters)
Band 4 21.0 – 21.45 MHz (15 Meters)
Band 5 28.0 – 29.7 MHz (10 Meters)

There is a DB9 serial connector on the back and the rig can be controlled as if it was an FT-817 (ah the irony). I'd love to see something like this with a USB cable for both control and audio - that would make a terrific digital modes transceiver.

F1 and F5 increase or decrease the tuning rate while F2-F4 operate soft buttons which show on screen.

I'll report back next weekend when I've had some contacts, but my feeling so far is that this is a pretty good little short wave radio that covers 0.1 - 30MHz continuous and as a bonus transmits too.

The user manual pdf is here.

Here's a contact with Mal, VK2BMS.

Thanks Mal.

Saturday, September 07, 2013

Raspberry Pi interfacing with piface

The Raspberry Pi has turned in to a very flexible platform for dedicated computing tasks. I run one as an OpenVPN server, in the office we have one displaying server stats on a big TV. This week I purchased a PiFace board that provides a bunch of I/O controlled via an SPI interface.

I found the documentation covering getting started is a bit confusing so here's my summary based mostly on the Element14 document.

sudo apt-get update
sudo nano /etc/modprobe.d/raspi-blacklist.conf 
# comment out blacklist api-bcm2708
sudo modprobe spi-bcm2708
bash install.txt

sudo reboot

And here's a simple python script to cycle one of the relays on and off along with the indicator LED.

# flash an led with piface

import piface.pfio as pfio
from time import sleep

    pfio.digital_write(0,1) # turn on
    pfio.digital_write(0,0) # turn off

So that's "hello, world", the rest is easy. (Control-C to get out of the loop by the way).

The board has 8 output bits. Bit 0 and 1 have relays connected to them, all have little on-board LEDs. They can be turned on or off like this:

import piface.pfio as pfio

There are 8 input bits, the first 4 have push buttons on the board. Here's how to read the first (0th) bit:

>>> import piface.pfio as pfio
>>> pfio.init()
>>> print pfio.Switch(0).value
>>> print pfio.Switch(0).value


For that last Switch() probe I'm holding down the push button nearest to the edge of the board.