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Author Topic: Wireless Cameras - Dangerous?  (Read 2754 times)

Offline j_mchattie

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Wireless Cameras - Dangerous?
« on: 09/05/2006 12:47:27 »

Im looking into a few wireless cameras on eBay.

There are three options:

200mw transmitter (50m distance)
800mw transmitter (200m distance)
5w transmitter (1000m distance)

I have a 200mw already, but it wont go through the 3 walls, one bookcase, and 20m that it needs to (the picture becomes noisy).

My question is, if I get an 800mw camera - is there any danger of it damaging either the fish, or the birds that it will be filming?

The frequency is 1.2ghz in all instances.

Is 800mw enough to harm me?

Thanks


 

another_someone

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Re: Wireless Cameras - Dangerous?
« Reply #1 on: 09/05/2006 13:40:13 »
800mW is not a lot of power less than 1 Watt not exactly comparable with the power of a microwave cooker.

Nonetheless, personally I might be cautious about sticking that kind of power right on top of your head for long periods of time, but even a distance of a few meters away will drop the amount of power you will be experiencing by orders of magnitude.

Also, if you are filming fish, very little of that energy would be able to penetrate very deep into the water anyway.

As for birds, again, it is all about distance.  What would happen if you actually placed such a camera inside a nest full of chicks, I really cannot say (no short term harm, but I have no idea about the long term), but if it is a few meters away, or the are only in the proximity for a short time, I cannot see any problem.

There have been reports that some birds are able to detect airport radar (but are not harmed by it), so it is possible that it might effect their navigation but again, I cannot see that small amount of power could even be detectable at all but the closest proximity.



George
« Last Edit: 09/05/2006 13:41:13 by another_someone »
 

Offline j_mchattie

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Re: Wireless Cameras - Dangerous?
« Reply #2 on: 11/05/2006 17:01:21 »

Isnt it more about frequency though?

And what to mobile phones give out (mw?)
 

another_someone

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Re: Wireless Cameras - Dangerous?
« Reply #3 on: 11/05/2006 19:07:28 »
quote:
Originally posted by j_mchattie
Isnt it more about frequency though?

And what to mobile phones give out (mw?)



You're talking about 1.2GHz, microwave ovens typically run at 2.45GHz not a lot in it.

According to http://www.techmind.org/gsm/, peak power for a GSM handset can be between 1W and 2W, but they can drop to 20mW if they are sufficiently close to a base station.

http://www.techmind.org/gsm/
quote:

Background


Contemporary 'digital' mobile phones in Europe operate using the GSM (Global Systems Mobile) system. There are two frequency bands allocated to GSM mobile phones, one at 900MHz, and one at 1800MHz. GSM uses a combination of frequency division multiple access (FDMA) and time division multiple access (TDMA). What this means in reality is that within each band there are a hundred or so available carrier frequencies on 200kHz spacing (the FDMA bit), and each carrier is broken up into time-slots so as to support 8 separate conversations (the TDMA bit). Correspondingly, the handset transmission is pulsed with a duty cycle of 1:8; and the average power is one eighth of the peak power. Once a call is in progress, the phones are designed to reduce the radiofrequency (RF) output power to the minimum required for reliable communication - under optimum conditions, the power can be set as low as 20mW (one hundredth of full power). Battery consumption and radiation output of the handset is further reduced by using 'discontinuous transmission' (DTX); the phone transmits very much less data during pauses in the conversation.
Code: [Select]
              Base station transmit  Handset transmit  Peak handset power  used in the UK primarily by
GSM900              935-960MHz            890-915MHz          2 watts         BT Cellnet and Vodafone
GSM1800 (PCN)       1805-1880MHz          1710-1785MHz        1 watt          Orange and One2one
The basic handset transmission consists of carrier bursts of 0.577ms duration, repeating every 4.615ms, giving a repetition rate of 216.7Hz. The data is encoded using a phase modulation scheme known as 'Gaussian Minimum Shift Keying' (GMSK) and a symbol duration of about 4s, which doesn't affect the carrier amplitude. Owing to the coding and control protocols, every 26th pulse is omitted during a conversation, leading to a component in the output modulation at 8.33Hertz.





George
 

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Re: Wireless Cameras - Dangerous?
« Reply #3 on: 11/05/2006 19:07:28 »

 

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