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Comment Frequency Hopping vs Direct Sequence (Score 4, Informative) 67

I don't mean to denigrate her contribution in any way, but Lamarr's frequency-hopping spread spectrum is not the one used in CDMA mobile phones. It is used in Bluetooth.

Lamarr invented "frequency hopping" while CDMA cellular and GPS use "direct sequence". Frequency hopping is just what it sounds like: a narrowband transmitter is continually retuned to a different radio channel. Unless the receiver tuning follows the same sequence at the proper times it cannot receive the transmission.

Direct sequence XORs a narrowband signal with a high speed pseudorandom "chip" sequence, and the receiver undoes this operation by XORing it again by the same sequence properly synchronized in time. It closely resembles a keystream-type encryption system, though the "keystream" is not necessarily secret. The main difference is that direct sequence is a wideband signal while, at any instant, a frequency hopped signal is still narrowband.

Each method has advantages. Frequency hopping can be especially resistant to strong narrowband jamming, so it's a favorite of military systems (Lamarr's intended use). Direct sequence is easier to use with coherent modulation so it tends to use transmitter power more efficiently, and it can often provide precise timing and positioning as a side benefit. Or, in the case of GPS, as its primary purpose.

While CDMA mobile phones were very important in the 1990s and 2000s, it is now being replaced with LTE (Long Term Evolution), which uses OFDM - Orthogonal Frequency Division Multiplexing. So do many other modern terrestrial digital communication systems including DSL, HD Radio, DVB-T (but not ATSC), WiFi and DRM (Digital Radio Mondiale).

Comment Re:Somewhat hyped (Score 1) 48

How is this relevant? The algorithm is for speeding up Markov Chain Monte Carlo (MCMC) analyses, which are very commonly used in science to examine posterior probability distributions for a particular model. I run MCMC codes most weeks and they're becoming increasingly more common in my field of science. Being able to speed up the analysis by a large factor to avoid model likelihood evaluations would be very valuable.

Comment Re:Babylon 5 (Score 1) 363

Okay, someone please explain the appeal of Firefly. I should be smack on its target audience. It was clearly inspired by one of my favourites, Blake's 7. Many many people whose opinions I trust love it. So I watched the entire run. And I couldn't stand it. I hated the characters (not in a Blake's 7 way, where there are no morally good characters but lots of interesting ones, but in a I-don't-care-what-decisions-they-make way), I hated the plots, I hated the western/sci-fi crossover style. I really can't understand the appeal.

Comment No more tourist attraction (Score 1) 336

My guess is that the Metropolitan Police is far from gone from the area; they simply got tired of being an overt tourist attraction. The Ecuadorian Embassy is right around the corner from Harrod's and also the hotel where we stayed as tourists last summer. I got the definite impression that the police on duty were photographed a lot...

Comment Re:I feel you... (Score 1) 283

Updating is required to maintain a secure device. I had had the device for just over a year when it updated. The change that Apple made was not the raise the price, they already have corned the market on over pricing their devices, but to make it that older devices do not offer functionality offered to newer devices. This is reasonable. If Google decides to push a software update to a device THEY are responsible for ensuring it works. Devices do not "degrade with upgrades" that is a contradiction of terms. A software update should not be pushed to a device that cannot handle it.

Comment Re:I feel you... (Score 1) 283

You are essentially saying that he can fix the issues pushed onto the device by the developer, in this case Google. Why is that an acceptable "solution?" When Apple did this with the iPhone 3g people very annoyed (rightfully). I got a free upgrade from Apple after complaining about it repeatedly. I can't even find out who I WOULD contact with regards to my 2012 Nexus 7 being so slow. It is fine and daddy to say that a user can make their 3 year old device do amazing new things by rooting and installing other software; telling a user that they can fix issues pushed on them by the developer of software is not. This is one reason why Apple totally hampers older devices at the OS level (e.g. no multi tasking older devices that will get iOS 9).

Comment Re:How could it possibly "work" for 300M people? (Score 1) 281

I think the "large welfare state[s]" are providing a minimum income to their citizenry. This has very much the same effect as a minimum wage in countries where the economy can handle either the high taxes or the increased costs of a higher minimum wage. The conclusions you draw from the two systems you are comparing do not follow from their forms of economy so much as their underlying economic base which existed before the socialization (sorry bad term but you get my drift) of Europe. Basically correlation does not equal causation.

Comment Re:Great idea (Score 1) 220

I know you are using, the now meaningless, quotes around "deadly force" but do tone down the hyperbole. While it seems to be an ill-conceived idea to empower corporations to retaliate against perceived attackers it is not "deadly" in any sense (unless of course it is some other stupid corp who placed life critical equipment on the internet).

Comment Re:Smart (Score 2) 291

You are giving a single data point. Perhaps you should provide a data point further in the past to at least give a slope to your assertion? Here let me help. The effective tax rate on the top 1% has been falling since 1995 while for everyone else it is at a historic low. However it is important to keep in mind that the percent of wealth owned by that 1% has increased dramatically: the ratio of 50th to 99th wealth has gone from 0.024 in 1995 to 0.01 in 2013. In particular the 50% wealth level has DROPPED while the 99% wealth level has almost doubled.

Be careful when a loop exits to the same place from side and bottom.