19hertz

ramblings of an electronic engineer.


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Sydney Trip: Day 1 – Harbour Bridge and Opera House

Having accumulated a reasonable amount of annual leave at work I decided it was about time to take some time off and go have a holiday. Normally I like to take holidays around public holidays to get a little extra mileage with my leave so noting that Brisbane had a public holiday on Wednesday for the Ekka and that Sydney Mini Maker Faire was on the following Saturday I decided to take some leave and head down to Sydney for 4 days with a day free at home either side of the trip to work on projects and relax.

So come Thursday (two weeks ago at the time of posting this) I flew down to Sydney for my 4 day mini adventure. After arriving in the city, dropping my bags off and having lunch and a coffee at a local cafe (one of 5 I visited during my trip) I felt it was time to do some exploring and photography. After a vague look at a map I headed off northwards towards the St Mary’s Cathedral then westwards towards the opera house via the botanical gardens and art museum.

It was somewhat unfortunate that in order to photography some of the points of interest along the way I had to shoot into the sun which messed about with the auto exposure and dynamic range of the shots. However I managed to fix the majority of the issues in post and came away with some photos I was happy with. Going another time though I’d definitely like to go out and photograph the opera house and bridge in the morning and at night.

To wrap up the day I visited a few shops in the city buying some board games to play back up at home, had dinner at a Japanese restaurant which served probably the best Takoyaki (Octopus Balls) I’ve had to date and finally went to a telescope viewing session  at Sydney Observatory. All in all a pretty good first day down in Sydney.

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Startrails!

After coming across this post on Petapixel on start trails I though I’d give it a go on the timelapse I made last week. Here is the result.

stackedImage

Here is the same technique applied to a timelapse in the same location as the picture above. I hindsight this picture is really out of focus.

stackedImage2

I also tried it on a daytime timelapse of Hinze Dam a few months ago with interesting results.

stackedImage3


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Air Quality Logger Project – Research and Specifications

While riding my bike around a few weeks or so ago I was wondering what the air quality was like on the Gold Coast compared to other cities for example Brisbane and the world for that matter. Around the same time I had also seen a project that logged sunlight data to a sd card to determine which plant would be most suitable for the location. So an idea quickly came together to create a device that I would be able to attach to my bike and log air quality data as I go riding about.

Air Quality Factors

So after doing some research on air quality I found out the following:

  1. The three main factors that determine the air quality are:
    • Particulate matter (PM2.5/PM10)
    • Nitrogen Dioxide (NO2)
    • Ozone (O3)

    There are others but these are the commonly measured factors.

  2. The Gold Coast only has two air monitoring station (in Helensvale and Beenleigh)
  3. “Air pollution problems may occur in the next 20-30 years” due to increase in traffic.

I won’t really require data for comparison until I’ve completed the majority of the project and have some data of my own and finish calibrating the system. I actually had a bit of trouble finding current data but got there eventually (amazing what happens when you read the entirety of an article rather than jut skipping to the data and graphs) and found the current air pollutant data at the National Pollutant Inventory.

Specifications

Considering the initial research on the topic it’s important create some specifications of what the project once fully completed should be able to perform. Here is what I have come up with.

  • Detect particulate matter, ozone and nitrogen dioxide.
  • Detect location of measurement (GPS).
  • Store air quality and location data.
  • Have enough power for one day of measurement.
  • Portable and weatherproof.

Realistically some of these may not be possible to budget and practicality constraints but the specifications can always be changed at a later stage.

The Plan From Here

Alright so from here over the next few weeks I’ll hopefully be getting some parts for the project in (sensors) and I’ll be  working on a circuit diagram for the project. I plan to use the Arduino microprocessor for the project because I’m familiar with it’s architecture and programming however once I have the system working properly I plan to redesign the system to operate on a microprocessor that is just sufficiently covers the technical requirements of the project. This should reduce power consumption and price of the system. To start off I’m going to start work on getting each component working individually then interface multiple components. So to start off with I’m going to work on the data logging aspect of the system, mainly because the hardware (a sd card breakout board) has already come in and I can start to work on it. I’m thinking since my sensor hasn’t come in yet I’ll try logging air temperature because I’m 90% certain I have a temperature sensor lying around.

I’m really excited about this project and the various challenges I’m sure I’m face but it should be a fun ride. I’ll be posting progress here as I go and I’ve created a separate page on my blog where I will update with technical information from my posts. Any questions about the project or comments and suggestions let me know by leaving a reply.

Oh yeah I almost forgot, I plan for the whole project to open source and open hardware including all of the data I collect from the project. So you can build your own and use the data for free.


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Benfords Law

Benfords Law is one of the most fascinating things that I have ever come across, however to explain what it is lets play a game (actually the game I learnt about Benford law). Lets firstly list the numbers from 1-9

1 2 3 4 5 6 7 8 9

Now we are going to group these into two groups, one from 1-3 (Group A) and the other from 5-9 (Group B). For the purposes of our game the number 4 will be a dead zone that us no points will be gained on it (keep reading it will make sense).

(1 2 3) 4 (5 6 7 8 9)

Now the way the game will work is we will pick each pick a different group of numbers group A or group B. Each round we will then times two unknown values together in wolfram alpha and look at the first digit of the number, if it falls in your set of numbers you get a point, first to ten points wins.

So for example it first round might be the mass of the sun * the number of people living in america = 6.14×10^38 person kilograms (mixed units can be strange). The first digit is a 6 therefore group B would get a point.

Again if you searched for US debt * planks number = 15.86 trillion planck US dollars, group A would get a point.

So we start our game and you been a logical rational human begin choose group B because there are more numbers in that particular group and you have more changes of the first digit been one of your numbers. I however foolishly choose group A.

Now let me tell you why I will win almost every time. (hint its due to benfords law)

So we expect the probability of the first digit been any given number to be something like this:

In actual fact the probability distribution looks something like this:

So yeah, Benfords Law essentially states that there is a logarithmic probability distribution of the first digit of most lists of real-world data. This means looking back to our game the actual probability of each group winning per round is:

Group A: 60.2%

Group B: 30.1%

‘Dead Zone’: 9.7%

I’m not going to get into why the probability is distributed this way, however if your interested check out Wikipedia or Wolfram MathWorld. (My way of saying I can’t explain why it is that way)

Benfords Law works for a large range of real life data, testingbenfordslaw.com has many various examples of real life data sets that follow Benfords Law for example twitter users by followers count.

There are however some data sets that do not follow Benfords Law these include

  • Data sets where numbers are influenced by human thought (eg. shopping centre prices which are set through psychological thresholds)
  • Data sets where numbers are assigned (bank account numbers, telephone numbers…)
  • Data sets of bank accounts with a built-in minimum or maximum

In the real world Benfords Law is actually used as part of a set of analytical tools to detect fraud. If data sets in accounting don’t follow the logarithmic probability, accounting fraud has likely taken place. Here is an example of Benfords Law used to detect accounting fraud.

So there you have it. Benfords Law. One of my favourite counterintuitive curiosities.


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Perseid Meteor Shower


I saw this picture on /r/pics a few days ago of the Perseid meteor shower, photographer David Kingham spent 7 hours shooting to get this photo. The shot is comprised of 23 photos, 22 of the meteors/stars and 1 of the foreground been lit up at sunrise.

I had to overlay each shot that had a meteor in photoshop, lower the the opacity to 50%, rotate the image based on polaris to match them up, then erase everything on that layer except the meteor.

I was planning to go out and shoot the Perseids shower however as my friend pointed out the Perseids are primarily visible in the northern hemisphere, not here is Australia. So I guess this is something to remember for the next opportunity I get to shoot a meteor shower.

Bird Watching

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So normally I start my Saturdays by sleeping in a bit, however not this weekend. Early Saturday morning I braved the cold and lack of sleep in to go  bird watching with some friends at the spit. Equipped with my trusty 60D and 18-135mm I had a great time photographing the local wildlife and trying to remember a plethora of bird names. Can’t wait till the next trip.

Fist Shot of the Day

Bush Stone-curlew

Bush Stone-curlew

Bush Stone-curlew

Blue-faced Honeyeater and Rainbow Lorikeet

Rainbow Lorikeet

Silver Eye

Double-barred Finch (Left) and Male Superb Fairy-wren (Right)

Male Superb Fairy-wren

Besides birds there were also a couple of other photo opportunities.

Moth/Butterfly of some sort

Backlit Leaves

Wild Flowers!!!

This gallery contains 12 photos