How well do Bluetooth signals propagate?

Propagation questions, answers and general information
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Alex Cator
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How well do Bluetooth signals propagate?

Post by Alex Cator » 30 Dec 2014 21:38

I know about how rubbish many digital signals are, in terms of the way they propagate. DAB+ has a better sound than DAB, so it would be a good upgrade from DAB, but I do know that I'll miss the nice propagation of FM and AM broadcasting when DAB+ takes over. Another digital radio standard is Bluetooth, a standard I do not understand very much about, often used with transmitters in the milliwatt range for consumer use, such as transmitting music wirelessly to a Bluetooth speaker, and also for transmitting telephone audio from smartphones to car audio systems. Transmitting 250kW on FM (band 2) can cover an administrative region of the UK almost completely, perhaps with a few lower power relays in valleys or built-up areas. DAB transmitters in the UK tend to be lower power, e.g. 5 kW (maximum) for the main TX in an area, with loads of little ones (e.g. 250 watts) dotted around all over the place. How far beyond the transmitter itself would a 250kW DAB transmitter cover, and also, but more ambitious, how far away would a 250kW Bluetooth transmitter cover? It would be funny if Bluetooth became the transmitting standard for radio broadcasting, but you would have to select 'all devices' on the transmitter. Wow! I think it would be very ambitious, but funny, to build a 250kW Bluetooth transmitter, because Bluetooth propagates so badly (I think!), and it is not affected even by tropospheric propagation.
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Tim Bucknall
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Re: How well do Bluetooth signals propagate?

Post by Tim Bucknall » 31 Dec 2014 11:54

theres some good wi-fi distance records from the early days before 2.4mhz became clogged up

you should do some blue tooth experiments - someone has to be the first :-)
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Sniffingmoose
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Re: How well do Bluetooth signals propagate?

Post by Sniffingmoose » 31 Dec 2014 17:48

Hello

Not sure about the Bluetooth, the key to higher frequency DAB propergation is having nothing in the way and no co channel signals. As for long distance DAB Dx I have been suprised just using my Pure DAB Sports Personal Radio (headphone lead as an antenna), I have recieved the Cornish MUX, and Ireland from the Pembrookshire coast footpath, Nothern Ireland Mux from the Llyn Perninsualer and most suprising of all, Norway DAB Mux's when walking along the sand dunes of the Northumbrian coast and again Norway from the cliffs of the County Durham, I could not hear Norway on Band 2 at the time.

Lift conditions have caused South Devon and London Mux's to be audiable here in Burton on Trent this year. So open spaces and seapaths seem good for DAB DX. however in the UK the band planners seem to use the same channel evey 50miles or so for local MuX's, I think this is to deliberatly limit the distances the local MuX's propergate outside their intended area. So maybe we will still have a hobby if Band 2 is switched off in years to come.

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Alex Cator
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Re: How well do Bluetooth signals propagate?

Post by Alex Cator » 02 Jan 2015 20:12

Sniffingmoose wrote: So maybe we will still have a hobby if Band 2 is switched off in years to come.
Yes, until DAB+ (as it will be then instead of DAB) gets switched off, we will do DAB+ DXing. When all terrestrial radio and TV gets switched off, and people are using the internet to listen to things from all over the world on their smartphones at the touch of a touchscreen, DXing with real propagation will become a thing of the past, according to John Faulkner G1VVP. A DAB or DAB+ receiver needs higher Band 3 gain than Band 2 gain for equal DAB and/or DAB+ gain to FM gain. What I was asking about the DAB is not really about local muxes, but about the BBC and Digital One national muxes. Why do the sites that transmit 250 kW FM BBC nationals and Classic FM, only transmit (e.g. 5 kW) BBC and Digital One national DAB, and have tiny little (e.g. 250 watts) transmitters dotted around their broadcast areas? What is the problem with 250kW DAB? Would it cover similar area to 250 kW FM on Band 2? As this thread is titled to be about Bluetooth, I am asking if anyone knows how far a 250 kW Bluetooth transmitter would go?
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Peter Körner
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Re: How well do Bluetooth signals propagate?

Post by Peter Körner » 19 May 2015 09:04

>Why do the sites that transmit 250 kW FM BBC nationals and Classic FM, only transmit (e.g. 5 kW) >BBC and Digital One national DAB, and have tiny little (e.g. 250 watts) transmitters dotted around >their broadcast areas?

Because DAB coverage is worse than FM due to the higher frequencies used. This also means generally worse reception indoors, as has been noted in tests. With previous L band DAB tests this gets even more obvious… The L band is basically useless for any reasonable broadcast coverage.

>What is the problem with 250kW DAB?
You would never get the intended increased DAB coverage simply by increasing Tx power.

>Would it cover similar area to 250 kW FM on Band 2?
Never.

>I am asking if anyone knows how far a 250 kW Bluetooth transmitter would go?
Bluetooth basically is a “line-of-sight technology”. Any buildings, trees with leaves etc attenuate the signal. Nobody in his/her right mind would ever build a 250 kW Bluetooth transmitter!

Instead see:
http://digitalradioinsider.blogspot.se/ ... .html#more

Peter

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Julian Hardstone
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Re: How well do Bluetooth signals propagate?

Post by Julian Hardstone » 19 May 2015 09:52

Re dx records, according to the UK µw Group the 2.3GHz terrestrial record stands at 3980km, JUL 1994 http://www.microwavers.org/indexs.htm
but how far is the moon and back? That's the amateur record, held by all eme om's

Re Bluetooth, I presume it is a two-way protocol so one device converses with the other, so 250kW would get you no further to a µW device

Peter Körner
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Re: How well do Bluetooth signals propagate?

Post by Peter Körner » 21 May 2015 12:37

> Re Bluetooth, I presume it is a two-way protocol so one device converses with the other, so 250kW would get you no further to a µW device

There are different classes and modes. For class 1, the highest power allowed is 100mW.
I have heard of cases where this has worked over a 150m distance - with free line of sight.

Alex Cator
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Re: How well do Bluetooth signals propagate?

Post by Alex Cator » 21 May 2015 18:26

Alex Cator wrote: Yes, until DAB+ (as it will be then instead of DAB) gets switched off, we will do DAB+ DXing. When all terrestrial radio and TV gets switched off, and people are using the internet to listen to things from all over the world on their smartphones at the touch of a touchscreen, DXing with real propagation will become a thing of the past, according to John Faulkner G1VVP.
I will DX mobile phone networks for years to come. I may get an old mobile phone with an external antenna socket, my second phone which will be along with my jailbroken iPhone 4.
I will have a Yagi for mobile phone DX. I may even design a new one - I am going to design a high gain Yagi for Band 3 (probably called the 'Cator 13'), which would have 13 dB gain and maybe about 20 elements and hopefully 40 dB F/B ratio. This Yagi would be designed with some antenna optimiser software, and I wish K6STI's was still available. Brian, if you are reading this, could you please upload a copy of AO 9.xx?
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Peter Körner
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Re: How well do Bluetooth signals propagate?

Post by Peter Körner » 22 May 2015 08:29

>DXing with real propagation will become a thing of the past,

That will take a VERY long time.


>I may get an old mobile phone with an external antenna socket,

Old Sony Ericsson phones have a dedicated special 50 Ohm socket.


>along with my jailbroken iPhone 4.

iPhones are among the worst in terms of antenna performance.


>I will have a Yagi for mobile phone DX. I may even design a new one

You realize that you need to cover two separate bands?


>I am going to design a high gain Yagi for Band 3 (probably called the 'Cator 13'), which would have 13 dB gain and maybe about 20 elements and hopefully 40 dB F/B ratio.

You have got a lot to learn…, but nobody is stopping you.


>This Yagi would be designed with some antenna optimiser software,

It takes much more than pressing a button to design a good antenna…


>I wish K6STI's was still available. Brian, if you are reading this, could you please upload a copy of AO 9.xx?

Considering Brian’s experience of software piracy, I very much doubt that he will upload anything!
There is A LOT of work behind his software…

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