* Posts by bwalzer

15 posts • joined 27 Apr 2010

Leaky security could scuttle global ship-tracking system


We have already had this pointless discussion...

We have already had to listen to this kind of nonsense with respect to the ADS-B system as used for aviation. So I suppose that we will have to endure this every time some "security researcher" becomes aware of a new broadcast position reporting system.

Such systems are inherently susceptible to spoofing due to the nature of what they do. The researchers tend to suggest that a secure system is possible without actually proposing anything. The implication here is that every sailboat in the world could be registered in some system and that the credentials for such a system could somehow be kept secure in hardware that the owner has access to. That is obvious nonsense. The users of such systems are aware of their shortcomings and do not allow information derived from such systems to force them to do dangerous things. That is in the same way that they are expected to be able to withstand incorrect information from any navigation aid.

The stuff about making an Iranian "nuclear boat" appear somewhere is particuarly dumb. Plot elements from terrible action adventure movies should not appear in security reports.

Next the security researchers will be publicly appalled at how easy it is to spoof navigation lights. It only requires access to coloured flashlights! ... and marine radios... anyone can buy a marine radio and generate all the false distress calls and position reports that they want! This is obviously because lights and radios were invented before there was an internet ... or something...

2012: The year that netbooks DIED


A narrow definition of "netbook"

So a netbook needs to have an x86 processor in it? Chinese makers are churning out 7" ARM based devices running Android for around $60US. How are those not netbooks?

North Korea's satellite a dud, say US astroboffins


This seems a bit mixed up...

... but that's OK. Various other media outlets got it wrong. The orbit is fine. In fact they pretty much nailed it if they are doing earth observation. That's pretty hard to do as things go and represents a fairly significant technical accomplishment. The satellite is tumbling. That may not mean the end of the mission. They might be using a stabilization technique that takes a long time. Such techniques have limits of course...

There is no real extra risk of collision. Many (most?) science satellites in low earth orbit have no method of propulsion and none would be expected for a first crack at a space vehicle. Low earth orbit is littered with junk. One more object will not change things at all. SOP is to track as many objects as possible and then move any valuable satellites out of the way if there is a conflict. There is nothing like air traffic control for low earth orbit.

HP Pavilion dm1-4125ea 11.6in netbook

Thumb Down

Still waiting...

It weighs half again as much as my Asus 701 and is significantly larger. The better cpu performance and battery life can't really make up for such a significant departure from the netbook form factor.

... and yeah, glossy screens are terrible...

Software bug fingered as cause of Aussie A330 plunge


Seat Belts...

They were likely referring to the normal suggestion that passengers should keep their seat belts fastened whenever possible. ... which is good advice in any case. It is more common for unexpected turbulence to cause passengers to gaily bounce around the cabin. The old trick of leaving the seat belt very loose, but attached, would of worked here (with perhaps some minor bruising).

LightSquared to magic away GPS interference in 2 weeks



Just a quibble. Intermodulation and IF images happen entirely in the receiver. There isn;t anything you can do at the transmitter other than avoiding frequencies and combinations of frequencies that can stimulate these sorts of problems.

This in the end comes down to a matter of opinion. The battle between the users of satellite downlinks and terrestrial transmitters is ongoing. This is merely a single battle...


"The rules from the FCC and similar bodies round the world are quite clear; if you don't design equipment to reject other people's legitimate transmissions, that's your problem not theirs."

Err, no, practicality is a huge part of the frequency allocation that regulatory bodies do. Broadcasting is an excellent example of this. The likely spurious reception of the receivers used in a particular area exclude many possible frequencies for people to put their TV or radio transmitters. Things like intermodulation and IF images are important as well as "adjacent-channel interference".

This is particularly important for satellite downlinks. Transmitters in space run off of solar cells so the links are generally engineered with little extra margin. They are thus very susceptible to interference. The normal practice is to assign guard bands on frequencies adjacent to downlink bands where terrestrial transmitters are not allowed.

There is a tradeoff between loss and how sharp you can make a filter. The filter that is delivered will most likely have too much loss to be practical for the application ... unless of course there has been some sort of recent breakthrough that no one has heard of yet...

FCC demands AT&T prove spectrum scarcity claims


Bandwidth vs Spectrum

@Paul Shirley

It is really hard for a mobile user to tell what the problem is when the bandwidth seems limited. The actual number of bits per second is ultimately limited by the signal to noise ratio you can achieve. You can't just crank up the power to increase the signal in most cases because one end of the link is running off a battery and the extra interference would just make things worse. At some point you can't use any more spectrum to improve things and you just have to bite the bullet and start installing more access points.

German boffins win prize for 'MP3 for phones'


I think there is an (probably) open codec that does this sort of thing...

Opus (http://opus-codec.org/) is reputed to be low latency, robust in the face of errors and does music. There is even an ITEF draft for it out right now...

Google open video codec faces second challenger


VP8/WebM not under patent attack...

Until someone can come up with an actual example of infringement and get to court with it...

WebM/VP8 is not under any sort of attack. It has all been unsupported speculation so far...

Asus Eee PC 1015PEM



It weighs 1.27 kg. Compare that to the original 701 at 0.92 kg. A better netbook has to be a lighter netbook. Portability is the point with these things.

Toshiba AC100 Android smartbook


A Linux based smartbook already exists...

... but the hardware support is not quite done yet. I bought a EFIKA MX Smartbook last week. It seems to be pretty much the same thing as the AC100 but is a bit cheaper and weighs a bit more. It came running Ubuntu Maverick. Some stuff doesn't work (vid acceleration, suspend, battery life info, bluetooth) but it is otherwise pretty much as claimed. It turned out it shared an unfortunate feature with the AC100; a glossy screen. Efforts to provide full hardware support seem to be ongoing.

iPad hits Asus Eee PC sales


Then perhaps they should make a better netbook?

I would love to upgrade my Asus 701 4G. So far everything I have seen is bigger and/or heavier and/or more expensive. I just want a stinking netbook. It does not have to run Windows. It does not need a hard drive. It does not need a keyboard I can type really fast on. I could even live with 800x480 screen resolution. Stop trying to sell me small laptops renamed as netbooks...

Samsung NB30 touchscreen durable netbook


SSD not really a go with Win 7

A friend bought a Asus T91MT so as to get a touchscreen netbook with SSD. It was pretty expensive with its 32GB of flash. Windows 7 has a min disk requirement of 16GB and often people insist on putting their own stuff on the disk. I doubt that we will see many flash based netbooks as long as Win 7 is popular and flash is relatively expensive.

Either XP or Linux is a solution to the disk space issue. The person with the T91MT now has Linux Mint on it (3GB).

Don't try to sleep with your iPad, doctor warns


There is probably something to this...

Circadian light is a personal interest. Some random Googling produced the fact that the iPad has a screen brightness of a bit over 300 nit. That is getting up into the range where some sort of effect might be detected. The problem is that figuring out how much light is too much is a bit complicated. The easy fix for the iPad (as for any other light producing screen) is to turn down the brightness. Since the iPad has an ambient light sensor it isn't really any extra work to do this.

The circadian light thing has all the attributes required to become the next magic rock. My somewhat cynical thoughts are listed here:



Biting the hand that feeds IT © 1998–2021