No offence Andrew, but here is my 2c:
I read the article yesterday on the plane, and am a little confused regarding the aim of the article. It’s barely general knowledge given on just over half a page, and not even that was thoroughly researched. The whole article should not have featured in the magazine as it contibutes little information of which a great part is wrong or totally incomplete.
Firstly, quoted from the AVSA magazine:
“In most countries around the world, either the government or a designated body, controls and allocates these radio waves, and decides what they are going to be used for – the military, the police, entertainment, etc.”
Although this statement is not entirely incorrect could be forgiven for that matter, it is still far from correct. The average person that reads it might think that the designated body decides how the whole frequency spectrum is going to be used. Not true…..
There is standardization bodies like: ETSI, ANSI, ARIB, ITU, etc. that decides on which frequencies are allocated to two way radio, radio and TV broadcasts, GSM etc. The regulator only decides which broadcaster, or which mobile operator gets what frequency in the allocated frequency band. For example: the broadcast frequencies are done by a standardization body, the regulator only decides how to subdivide the allocated frequencies to the different radio stations, and they control licenses. They do not decide which frequencies can be used for broadcasting.
Second error; quoting from AVSA: “From looking at the frequency rating, it is easy to see why FM transmissions sound better, even if they do not travel as far.”
WTF?
This statement is total nonsense. How is it obvious from the frequency spectrum that FM is better? Lower frequencies are always better, since it get attenuated less and there should have a better s/n ratio. But perhaps he missed to mention that because the spectrum is wider at higher frequencies there are more frequencies to choose from and therefore less interference. And because higher frequencies don’t travel as far as lower frequencies, it causes less interference? But to be honest I don’t think the writer of the piece had any idea of what I just mentioned.
The real reason why FM actually sounds better than AM is because the amplitude of the carrier stays constant and therefore has a constant s/n ratio, where as with AM the amplitude varies, which means where the amplitude is at a minimum it is closer to the noise floor and thus a bad s/n ratio.
Frequency spectrum:
Cell phones 824 to 849 MHz
My goodness, where did he get his information from? Anyone can do better by just using Google. 824 to 949 MHz is only the uplink (phone to base station) band used in GSM800 on the American standard, what about base station to cell phone? The full bandwidth for GSM 800 is 824 to 894 and GSM 1900 is 1850 to 1990.
But we’re not living in America do we? In Europe and Africa we use GSM 900 at 880 to 960 MHz, and GSM 1800 at 1710 to 1880. Cell phones also include 3G technology which operates mainly at 1920 to 2170 MHz.
I don’t think I’m being overly critical here. If someone wants to write an informative piece for a magazine, can they not at least do a little research on the topic first? These are only a few mistakes I picked up while reading? There might even be more
