Wireless Transmitters/Receivers

[Digital discos 0]

Right so I bought some wireless transmitters/receivers a while back. They are primarily used to send sky around the house but they seem to work perfect for audio.

 

Now I would like to separate my speakers further apart on ocacsions, and having the tx's/rx's would really neaten things up.

 

I used them once and every thing seemed to be great, but do you think there could be any downfalls?

 

Maybe interference?

 

Lack Of Audio Quality?

 

It just seems such a great waste to not use them!

[Gary 0]

There have been a few topics that mention using such devices, such as this thread....and others.

 

The main suspicion about these devices is interference from various items which venture into the same frequency band as the device. eg: Microwave ovens, Wi-fi hot spots (in some venues and some up-market hotels etc).

[jeffwall 0]

And if you next door but three neighbour has a reciever on the same frequency...he can listen to the crazy frog too! http://www.dj-forum.co.uk/html//emoticons/biggrin.gif

[Digital discos 0]

It would only be within the line of sight? Chris was telling me its only bad if your right next to a microwave or wireless laptop?

[ChrisPointon 0]

Anything operating on the same 2.4ghz frequency spectrum isn't too bad, since most Tx/Rx senders have a four channel switch, so you change to a new frequency, unless there are 4 devices in the immediate area, in which case you are screwed!. It's no greater or less odds than turning up for a gig in a large venue and finding a singer / dj / entertainer using a radio mic on the same frequency as yours!.

 

Wi-Fi can interfere with 2.4ghz devices, but finding an hotel with Wi-Fi is even rarer http://www.dj-forum.co.uk/html//emoticons/smile.gif , especially in smaller towns and counties.

 

Microwaves tend to bleed over the entire spectrum, so these are your worst enemy, and they will interfere over a distance.

 

As use of the 2.4ghz band increases and becomes more popular it probably will become more of an issue, hopefully the radio authority and DTI will licence new frequencies by then http://www.dj-forum.co.uk/html//emoticons/fear.gif

[Digital discos 0]

But surely 2.4ghz frequencies will only interfere if there in the line of the transmitter?

 

Will a microwave interefere even if it's say 20metres away? And not in the line of the transmitter or receiver?

[YourBigEvent 0]

QUOTE

It's no greater or less odds than turning up for a gig in a large venue and finding a singer / dj / entertainer using a radio mic on the same frequency as yours!.

 

I plugged in a radio mic last week, and it was on the same frequency as the local zoo, about a mile away, so I know all about the mating seasons of a penguin now.

 

Luckily I carry three radio mics.

[ChrisPointon 0]

QUOTE

so I know all about the mating seasons of a penguin now.

 

Well thats lucky because guess what questions the next DJU competition is going to consist of!!!

 

 

QUOTE

Will a microwave interefere even if it's say 20metres away? And not in the line of the transmitter or receiver?

 

More than likely, RF intereference isn't directional and doesn't have any set specification. Give it a try with your own system, whilst you are watching sky run the Microwave and see if you get lines down the screen on visual and a crackling sound over the Audio.

 

I now know, whenever the neighbour is using their microwave http://www.dj-forum.co.uk/html//emoticons/wacko.gif

 

As for quality, the links will offer good quality stereo audio transmission subject to there being no interference and used within their range. The closer you get to their maximum operating distance the more likely you are to see break up and drop outs.

 

For longer ranges, Ebay often have 1W and even 1.5W 2.4ghz TX/RX pairs available from the far east, and although you'll probably have to pay VAT when customs check them, they are still good value if you are likely to use them a lot, and being more powerful than standard units are useful for use in larger venues.

 

2.4ghz 1W Ebay Link

 

A 1W system will probably get you 700m - 1km range, but the downside is that with the RF output in the Uk limited to 100mw (0.1W) you also need to be aware that their use would basically be illegal http://www.dj-forum.co.uk/html//emoticons/sad.gif

[YourBigEvent 0]

QUOTE

A 1W system will probably get you 700m - 1km range, but the downside is that with the RF output in the Uk limited to 100mw (0.1W) you also need to be aware that their use would basically be illegal

 

No basically, it would be illegal

 

But the police would never find you because all they would hear on thier radios is Shania Twain http://www.dj-forum.co.uk/html//emoticons/laugh.gif

[transeurope 0]

In a world where people worry about the danger of cellphones (not that I do too much) I would be a bit uncomfortable about standing next to a 1W microwave transmitter all night.

 

Surely SOME regulations are there for a reason? http://www.dj-forum.co.uk/html//emoticons/533.gif

[brianmole 0]

QUOTE (transeurope @ Sep 2 2005, 12:02 AM)

In a world where people worry about the danger of cellphones (not that I do too much) I would be a bit uncomfortable about standing next to a 1W microwave transmitter all night. Surely SOME regulations are there for a reason?  http://www.dj-forum.co.uk/html//emoticons/533.gif

 

1 Watt is quite a lot of energy. Assuming 2.4GHz is close to microwave frequencies, I would be VERY careful here...

 

How do microwave ovens work? They create radio waves which excite the water molecule. Your brain amongst other things in your body consists mainly of water, and the potential of brain damage from microwaves is very high, so I would be VERY wary of using a microwave transmitter too close to my nut, and others' for that matter...

 

Why do you think there are interlocks on a microwave door then? How close do you watch your meal going round when you use the microwave? http://www.dj-forum.co.uk/html//emoticons/nono.gif http://www.dj-forum.co.uk/html//emoticons/wacko.gif

 

My father was a doctor of physics with particular expertise in waveguides, so he used to know microwave theory inside out and always pointed the dangers out to me from an early age.

[ChrisPointon 0]

Given that most GSM Mobile Phone can operate at upto 1W on similar Microwave frequencies, with a maximum of 2W when at a distance from a transmitter, should we be concerned about the Kids who spend all day permanently glued to their new Nokia's?, will we see glow-in-the-dark 8 year olds soon?

 

How many of you use a mobile phone several times a day, and for long periods?, is this not also a hazard? I mean you are willingly holding upto 2 Watts of Microwave power held in physical contact to the side of your skull with it's antenna pointing oscillating energy towards your brain, surely this more of a hazard than 0.1w - 1w several feet away used once or twice a year?.

 

Oh Dear!, what about Wi-fi Transmitters?, are you using a 2.4ghz wireless network whilst reading this?, where is the wireless router or access point?, under your computer desk zapping your genitals? is your wireless laptop sitting on your lap........ Oooops http://www.dj-forum.co.uk/html//emoticons/fear.gif .

 

Then there is a debate about phone masts operating at upto 10 Watts 24/7. You may be surprised at how close you actually live to one (or several) network masts, I learned that I am just 500 yards from two, it was secured to an old factory with no consultation with locals or announcements in the local press, they seem to breed like rabbits and multiply overnight, the masts that is, and not the locals! http://www.dj-forum.co.uk/html//emoticons/biggrin.gif .

 

See for yourself how close you live to various transmission sites, and where your nearest Mobile Phone Transmitter is by Clicking Here select either 'Find GB Site' or 'Find NI Site' then enter your postal code.

[brianmole 0]

http://www.dj-forum.co.uk/html//emoticons/wacko.gif http://www.dj-forum.co.uk/html//emoticons/fear.gif

 

My roadie Martin discovered that his mobile cased him a nasty toothache whilst he was taking a call on his left side. He moved his phone to the right hand side, all ok now.. http://www.dj-forum.co.uk/html//emoticons/censored2.gif

[RobbieD 0]

Yes a mobile phone may give out 1-2W when we use them. But how many minutes would you typically use a mobile during a 5 hour period?

 

Now if you were using a 1W sender for a gig, you would be exposed to a full 5 hours of microwaves.

 

QUOTE (brianmole @ Sep 2 2005, 07:30 AM)

I would be VERY wary of using a microwave transmitter too close to my nut, and others' for that matter...

Maybe you are missing an "s" on the end of nut. - Microwaves can also make you sterile.

 

Many years ago I worked with a guy who had been unable to have children due to spending the 60’s up masts working on waveguides.

[ChrisPointon 0]

QUOTE

Yes a mobile phone may give out 1-2W when we use them. But how many minutes would you typically use a mobile during an 5 hour period?

 

LOL you've never met ADS have you! http://www.dj-forum.co.uk/html//emoticons/smile.gif

 

Don't forget that a Mobile Refreshes every few seconds to "handshake" with the transmitter, thats the noise you hear when it's placed next to a radio / tv......or a radio mic! http://www.dj-forum.co.uk/html//emoticons/tongue.gif - ok this is at a substantially reduced power, but it's still powerful enough to reach the nearest transmitter several hundred yards away, so what is it doing to you when placed on a belt clip or around your neck over a several hour period.

 

 

[cj_65 0]

The radio transmissions are definitiely not limited by line of sight unlike

infrared. The strength of the alternate source can interact with the

the local building structure to create multi-path signals that will interfere

with your transmission.

 

 

[Gary 0]

Heres a happy thought, while the topics wandered off down this route.

 

A mobile phone handset (Class 5, as they're known) can indeed deliver 2 watts of power, if its at maximum range from a cellsite (network aerial) - the maximum range being 7 miles for a Class 5 handset. If you're nearer to a cellsite, the phone drops down its power level to 1 watt, half a watt etc ... in fact, most handsets have got either 16 or 32 different power levels to choose from. A handset will even take weather conditions (via signal strength) into the equation when choosing a power level.

 

However...all power emmited from a mobile phone is pulsed, not constant. So, during say, a ten minute call, your phone wont be emmiting signals for 10 minutes.

 

Along the same lines, did you know that when you dial someone from your mobile phone, the soft "Brrrr brrrr" noise that you hear (the ringing tone), is actually being "played" by the phone itself, rather than "wasting" a comms channel to get it to your phone - when (if!) the other person "picks up", then transmission is activated, until that time the phone is simply in "receive only" mode, waiting for a signal pulse to be sent to say "stop playing the ring ring sound and activate channel no...12345 for voice."

 

However, as for microwaving...(snigger)... True GSM networks (Vodafone and O2) operate at 1.8 Ghz.... PCN networks (T-mobile (Virgin) and Orange) operate closer to microwave oven specs at 1.9 Ghz. A microwave ovens magnetron (the microwave generator) operates at almost double that - 2.46 Ghz. So, even though theres a huge difference between microwave oven frequencies, and any type of digital mobile phones - if you were at all worried about possible effects - you could consider boycotting Orange and T-mobile (Virgin) networks, as this gets you a whole .1 Ghz further away from a microwave oven frequency.

 

Some interesting "parallel" research was rumoured to have been done in Ericsson about 8 or 9 years ago - when someone tried to take Ericsson to court for a "I've microwaved my brain" type case. People who advised that they detected symptoms when using any brand of mobile phone next to their head, were invited in for tests. The tests involved the person sitting in a chair, blindfolded, whilst a mobile phone was held upto their ear by a clamp, and a 3 minute call was made. Some of the test subjects reported discomfort during the tests, even when the "mobile phone" was swapped with a chocolate bar.

 

In ergonomic terms some people do indeed suffer from strange feelings along their neck, shoulders, jaw etc whilst holding a phone to their ear, especially during longer, or repetitive calls - but this is often found to be more muscular/pinch point related, than electronic - eg: If you held a penny to your ear for half an hour, your neck/shoulders and arm would feel different.

 

Myself, I dont beleive that theres anything to worry about. Gotta go, me mobiles ringing. http://www.dj-forum.co.uk/html//emoticons/wacko.gif http://www.dj-forum.co.uk/html//emoticons/biggrin.gif

Edited September 2, 2005 by Gary

[transeurope 0]

Hmm, I am not really worried about cellphones specifically for the reasons that other people have pointed out. Their average output is low. It is pulsed. They are designed to give out radiation in a way that minimises damage when close to humans. Some are better than others at this, that is why the phones have an SAR rating...even though some are worse than others all are designing with this in mind.

 

I am not sure how WiFi works, but I presume there are mitigating factors there too, like there are with cellphones.

 

Generally I tend to trust authorities until they give me reason not to. Phones and WiFi are highly regulated. 1W transmitters are not and even the people that use them in discos are using them in a way the manufacturers did not intend.

 

The 1W transmitter, it strikes me, is designed to be used on something like the eave of an outhouse. Very different situation.

 

Interesting chat so far, but no one has demonstrated to me how the transmitter works in a similar way to the phones to minimise damage...

 

[Gary 0]

QUOTE (transeurope @ Sep 2 2005, 09:24 PM)

Interesting chat so far, but no one has demonstrated to me how the transmitter works in a similar way to the phones to minimise damage...

Might be best to stick with a couple of very long leads for the moment then TE.

 

The only known potential health risks are tripping or strangulation.

Edited September 5, 2005 by Gary

[transeurope 0]

Well Gary, humorous and all as that comment was, the technology is out there somewhere...eg Phonic are selling relatively low wattage transmitters that use pulsing and encryption to minimise health risks and interference losses. They are available in the Asian market and shortly in the US...if they are not already out there.