[Sparky (OP)]

Posting this in General as it straddles several disciplines.
A subject of some controversy in the south of England.

The rollout of a new digital radio network is being delayed in many areas by protesters concerned about the possible health effects of the transmissions. There are many anecdotal reports of people suffering various symptoms which they attribute to the arrival of the system in their neighbourhood.

Are their concerns justified?

[Donnah]

Do you have more details, like the type of signal, and what opposers are saying is causing the problems?

[tweener]

Pure misinformed BS.  Sad situation.  In all the years of broadcast TV and radio, no one has ever shown any harm except in cases where they are very very close to the transmitter (like on the tower).  The real harm comes from watching the mind-numbing silliness several hours a day.

The "transmissions" of a digital radio system are really no different than those of broadcast TV or radio except for the format of what they are broadcasting.  They are still using FM modulation to carry the signal, but the signal is a stream of high and low "tones" that correspond to zeros and ones (binary digits).  A regular FM receiver can receive the signal, but there is no decoder for the binary.  That's why digital radio can make you pay for the programming - you have to buy the decoder to make sense of the binary data stream.

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John - The Eternal Pessimist.

[neilep]

John, am I right in thinking that there's a fair amount of radiation that comes off the actual television itself anyway ,as well as mobile phones etc etc?

'Men are the same as women...just inside out !'

[tweener]

There is some, certainly a measurable amount, but I've never found or heard of any compelling evidence of anyone having problems associated with the radiation.  In reality, radio waves all the way up through microwaves are relatively low energy and only act on the body by heating the tissues (like in a microwave oven).  Because the energy density of ambient radiation from appliances is so very low, the body doesn't have any trouble dissipating the heat with no damage.  Inside a microwave oven is different, as you know if you've ever put in a mouse.

In the early days of radar (the late 1940's and 1950's) the US was building large installations in the far north to detect over-the-pole bombers before they came over the horizon.  This required very high power at very low frequencies, certainly enough to damage human tissues (it would make nearby rabbits explode when it was turned on).  It wasn't long before the guards discovered that they could stand duty on the fence in front of the antennas and not need their parkas.  Unfortunately, this was a little too much and they did have some serious side effects.

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John - The Eternal Pessimist.

[Sparky (OP)]

Hi Donnah et al

quote:Originally posted by Donnah

Do you have more details, like the type of signal, and what opposers are saying is causing the problems?

This is Tetra radio system currently being installed across the UK by O2 on behalf of the police under the name Airwave.

Tetra uses PI/4 DQPSK digital modulation. It has a data frame length of 56ms which translates to a frequency of 17.63 Hz.  Opponents of the system have claimed that this ELF component and its harmonics appear as pulses in the waveform of the transmitted signal. Their concern is that this low frequency falls in the range "beta" brainwaves. There are anecdotal reports of headaches, sleeplessness nausea and other symptoms being experienced when a Tetra base station is installed. Some have pointed to cancer and even a vCJD cluster in the vicinity of Tetra radio masts.

Often cited in support of the harmful effects are a number of studies some years ago which showed an increase in calcium efflux from dead chick and rat brain tissue when irradiated with radio signal pulse-amplitude modulated at 16 Hz.

Cheers

Sparky