Beware of TELSTRA knocking on your door

Loose thoughts by Bjorn Landfeldt

SO, last night this young man comes past my house and rings the door bell. In very broken English he manages to tell me he is from Telstra and he is investigating some complaints by customers in my street. I am not a Telstra customer anymore but they manage my underlying infrastructure so I thought let's hear the man out. Over the last couple of weeks or so, I have experienced spurious carrier drops with my DSL modem so I shared this with him when he asked me if I had noticed anything lately. Between drop-outs there has been no noticeable problems. After having talked to him for a while he starts steering the conversation in the well known "I have something to sell you" direction. As it turns out, he just wanted to wast my time extra much by talking about problems in the infrastructure before the sales spiel but this one was interesting.

Knowing that I am using DSL (since I don't have a cable plan with Big Pond) he told me that my intermittent loss of carrier was because DSL is an inferior technology and that I should change to a Telstra cable modem plan instead. There were two reasons apparently, 1) cable modems are always much faster than DSL and 2) I experience loss of carrier because there is so much congestion during peak hours because my neighbours are using all my capacity.

I accept that I live in a city where I cannot even get away from sales reps in my home day or night, but having to endure blatant lies like this is just a sign of corporate management in absolute ethical crisis. I am lucky to understand this and being able to kindly decline but what about all those people who are not telecom people and who actually trust what an old reputable organisation like Telstra tells them? Telstra is so dominant on the Australian market that there is no need to resort to such methods. In fact, they can leave people alone in their homes at dinner time all together and still pay out good dividends.

A different level of impact

Loose thoughts by Bjorn Landfeldt

After the government released its report on Internet content filtering senator Conroy released a statement that the government will test P2P filtering as such tools currently exist. This is very interesting because the bar is raised considerably if this is the case.

In the report I did not raise and strong concerns with performance degradation at the ISP level when comparing HTTP requests to a blacklist. I believe the performance penalty can be significantly reduced by purchasing additional equipment and the ISPs can be compensated for such roll out. The current trials can actually answer some of the questions as to the performance penalty and cost to alleviate them in terms of additional equipment purchases.

However, with P2P filtering the situation is very different. In this case, the filtering system has to do deep packet inspection to figure out if something should be banned or not and this is very different to checking terminating address. The deep packet inspection will be used to try to identify what kind of content is accessed since in a P2P content distribution network end addresses are useless. This puts us in the realm of dynamic filtering which pretty much is the worst nightmare for the Australian ISP industry and necessarily will mean significant performance penalties for the Australian public. Even if some video in a bit torrent would be called "child abuse that is illegal in Australia and should be filtered by the government" a filter would have to perform analysis of this text to determine if the media should be filtered. Changing the name of this file to "daisies in summer" and the filtering system would have to analyse the content of the video itself to determine if it is illegal and should be blocked.

In addition to performance penalties, such system raises much stronger privacy concerns. Even if very little content would actually be blocked with such system, someone is really checking how Australian citizens are using their network connections.

It will be interesting to see how this will pan out.

It is a shame

Loose thoughts by Bjorn Landfeldt

Over the past couple of days there has been lots of articles and blog posts about Internet content filtering in Australia. Sine I am involved in this debate I have spent quite some time to go through the posts to see what interesting thoughts and views are out there.

I am a bit surprised at the emotional charge this issue has and really think it is a shame that the public debate is overshadowed by a sea of emotional outbursts and wild accusations. Especially, I think it is a shame that Senator Conroy's blog is flooded with such content, that is where people should try to be taken seriously.

I think it is absurd to compare the Rudd government with the Iranian or Chinese governments. I am also surprised that senator Conroy actually bothered to meat that criticism.

I am equally amazed at the notion that if you appose this scheme in any way you support child molestation.

It is becoming clear to me why this issue became such a prominent political issue in the latest election campaign and why it is so important to win political ground. It is a shame.

I am a proud Australian since 2007 but I was born and raised in Sweden. For all the lobby groups that are seriously concerned with children's welfare, I urge you to have a look at a country that is running at a few parsec higher speed than we currently are. I live in Sydney's South-West, in a suburb that had a plane crash, two shootings and a siege resulting in 4 dead all during last week. There is a lot of child neglect and abuse going on out here and this is something to really get upset about.

Of course, really caring for our children means a hefty tax bill......

Nothing is that easy, it is a shame.

Internet content filtering

Loose thoughts by Bjorn Landfeldt

There was an article in the Sydney Morning Herald this morning regarding a report I was involved in preparing for the Australian government late last year. The study was concerned with the feasibility of filtering content on the WWW at the ISP level. My own contribution to the report was not the major part and I mainly carried out a limited technical study

I feel that it is necessary to make a few things a bit more clear concerning the news paper article.

First, I don't think the study was very secret. In fact, the study made a wide consultation with the Australian ISP industry, content providers and other organisations / stake holders. There has been wide spread knowledge of this study even though the findings have not yet been widely released as far as I understand after reading the article. It is not my place to comment on at which time the government releases its reports even though I see no real reason not to release this specific report.

The issues raised in the report have largely been covered in preceding reports, at least the sections I was providing input to and even though they are very important issues to consider, I don't think they are damning since the issues are well known.

My stand on this issue is that there is a need to increase the scale of investigations if any such scheme should be made mandatory. If such a scheme is voluntary many of the difficult issues become obsolete or at least manageable. The following opinion merely reflects publicly available information that is not limited to the report. Anyone can search for this information in their local library or on the world wide web.

So, what is the big issue as I see it? A blacklist requires manual effort in order to determine what should be included. The Internet is a network of networked computers that carry information in many forms and realms, one of which is the World Wide Web. If we restrict ourselves to talk about only WWW, we have a global network with billions of pages worth of information. The information is made up of all different languages of the world and incredible diverse. Some information has a very high profile and some information has very limited visibility. Since a blacklist would rely on user reporting, it is questionable how efficient it would be to locate unwanted content in the first place. Second, every case would have to be tried to see if it breaches Australian law and falls within the categories specified for the filtering list. It will be a very difficult task to do this for content in the grey zone in all different languages. If the point is to stop child pornography, determining if a model is 19 or 25 in content from a different country with different jurisdiction is not an easy task and would be quite labour intensive. The next question is who is responsible for blocking of material that is legal if the wrong judgement is made?

The only way to identify such material quickly and significantly limit the risk of accidental access is to do some form of dynamic content filtering. However, the state of the art of such technologies is very limited in accuracy and if they are to be used there is a consequential performance impact on the response times of systems or at least an increased cost for the service provider. Current filters are rather good at detecting certain patterns of information such as a combination of many images and certain keywords usually means a porn site. However, there are at least two additional dimensions to consider. First, the current filters only look at such patterns, they do not try to analyse the actual content in any meaningful way. It is therefore difficult to distinguish between different types of content where there are similarities. For example, if a web site contains information about sex education or erotic content. Second, more and more content moves to other forms of multimedia and filtering and detecting the nature of content is much much harder in this case. For example, analysing a video and detecting that it has adult content is not a lightweight computational task. Separating sex education from porn is even harder. Third, if indeed there would be widespread filtering of content the providers would see a need to obfuscate content to fool filters. When we step into this realm it becomes very difficult for any filters to keep up.

This discussion can then be applied to an environment with other addressing realms than the WWW such as P2P networks and social networking applications and realms which shows that the level of difficulty is very high indeed. There is also a strong movement to anonymise users on the Internet to counteract information logging. Using simple tools such as VPNs to cross the Australian border would also enable circumvention of any centralised filtering scheme.

I believe it is a shame that the issue became a political issue in the latest election campaign. The question of protecting us from certain content is important and there should be a healthy and public debate about it. I have no knowledge of what other steps the government is currently taking to investigate this matter but I hope the scope of investigation is much broader than only doing a performance study of blacklist filtering.

I tried to download one of the free netalert filters for the computer my oldest daughter is using a while ago but the provider web site seems to be down. It is a shame, because I don't want her to see many things out there at her age, but I am making that choice and I accept responsibility for the over blocking.

Bjorn Landfeldt

Epoque DCL20 Wide angle lens review

Loose thoughts by Bjorn Landfeldt

So, I bought an Epoque DCL20 wide angle lens in New York a week back and had the opportunity to take it for a dive last weekend. Before I bought it, I could find no information about its performance on the web so it was a bit of a gamble whether to buy or not.

These are my initial thoughts without having had much time to really conduct experiments.

The lens is not very big, it doesn't really add much to my Ikelite and strobe arm setup for my G7, it adds a few hundred grams but that's pretty much it. The thread is so large and well defined it is easy to screw the lens on the port under water, I don't think there is much risk of damaging the thread with clumsy thick gloves etc.

The lens magnifies about 0.56 x so the angle is quite wide. My G7 has a 35mm equivalent of a 35 mm lens so I get about 19mm focal length (in 35 mm) with the Epoque attached. This is wide enough for the Ikelite standard port to get in the way and the result is vignetting (probably lots). I therefore also purchased the replacement port from Ikelite which is about 10mm shorter than the original port. There is a small limitation in the amount of zooming in one can do with this port because the lens eventually hits the port, but this is beyond the zoom when one can still focus in macro mode so I can't imagine it would be missed by anyone.

Above water one gets a bit of a shock when attaching the lens and taking a shot.



The first photo was taken without the Epoque at 35 mm (equiv.) and the second photo was taken at the same setting with the Epoque mounted. There were a couple of things I noticed straight away that worried me quite a lot.


First, there is obviously the barrel distortion to take into account. I was wondering what this would look like when taking photos under water. Second, there is significant softness around the edges (actually gradient from fairly much the center). Third, there is still a bit of vignetting happening. One obvious thing I noticed was the fact that the Ikelite housing has a pretty shoddy make. The camera is not centred in the lens barrel and when I first got the housing I had to cut of a lot of the light masking foam around the lens. With the Epoque mounted I get big black vignetting parts on the left side of the barrel and nothing on the right side. I lose quite a bit here since it means I have to crop much more to get rid of the vignetting.

So what happens under water?

I am pleased to say that my concerns are largely invalid when the lens comes in the water. First, I wanted to see what the coverage would be and how much distortion there would be so I took a few maximum wide angle photos of different things.


The visibility of the day was not too bad, probably about 8 or so meter (~24 ft) but there was a lot of particles in the water. The first photo would have been taken at about 3m from Taso and one can see that there is a lot of coverage at that distance and the diver is well defined since the distance is quite short.

Also, there is little evident barrel distortion in the photo. I then took some photos at closer distance and also tried to take some close up with the Epoque still attached. There was little evident distortion even at closer distances but closeups were heavily affected by the wet lens.

In the closeup of the snail one can clearly see how much blurring there is of the photo surrounding the snail. It doesn't look too bad in this specific photo, but it canreally make things bad.

So, all in all, I am looking forward to playing around much more with the lens and get a better understanding of what it can do and where there are limitations.

Automatic BCD???

Loose thoughts by Bjorn Landfeldt

A pair of undergrad students presented the outcomes of their thesis work on an automatic BCD in early October at the UNiversity of Auckland (Mechatronics).

The (invention) is a control system for managing ascents and descents of divers using an embedded system and a control loop for the inflation circuit. Apparently, there is also what is known as a cruise control whereby the (pilot) sets desired depth and the circuitry maintains that depth.

To me this sounds like a pretty stupid idea for a number of different reasons such as:

1) Increased reliance on equipment, especially for new divers who might be in a very bad position if the circuitry fails
2) One more point of failure (actually several)
3) Need to bring batteries for the BCD on a dive trip (or do you hook it up to 240V and charge overnight?)
4)Costly circuitry and mechanical control components
5)Completely unnecessary, buoyancy is a necessary skill to learn anyway and it needs to be practiced
6)etc.

I wonder what George Irvine III would say? Unnecessary Crap perhaps!

Leisurepro shop

Loose thoughts by Bjorn Landfeldt

So, I finally got to go to New York and visited Leisurepro's shop. It is tucked away on top of ADORAMA photography run by the same owners. After one has been shopping for dive gear on their web site for a while, and experienced the massive range of gear they carry, the shop is somewhat of an anti-climax. I fully understand that real estate on mid - lower Manhattan is pretty expensive contrary to the impression Macy's gives. But, the 40 or so sqare meters of Leisurepro shopping experience is pretty dismal. In the shop itself there is nothing to look at apart from a handfull of items so one has to be prepared when going there. The idea is to shop on the web first, and print out a list of items to look at. Presenting the list to the staff and the stuff comes up from the basement if it is in stock. Then you can see the things you are interested in up close.

So, what's the verdict?

Leisurepro serves a purpose, cheap prices for gear when one knows what to get. However, the shopping experience is far from satisfactory, if one wants some advice or just to browse this is not the place, there are many dive shops that do a much better job at this. I guess you can't have everything.