fkbreitl
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Multiroom audio system via RPi built-in FM radio transmitter

Thu Apr 20, 2017 1:50 pm

While searching for a simple multiroom audio solution I found current setups are quite sophisticated, expensive and experimental by involving new hard and software.

So I realized that the cheapest solution would be a simple FM transmitter that could distribute any audio signal from my living room amplifier to every other receiver in the house. Moreover I realized that with a wire (https://developer-blog.net/raspberry-pi ... io-sender/) and the software at https://github.com/rm-hull/pifm the Raspberry Pi is already a FM radio transmitter.

Now the only missing piece is the integration of pifm into an audio device that could be select via pulseaudio or something similar. At https://askubuntu.com/questions/78174/p ... ts-devices it seems like paprefs could be useful for this.

So I am looking for a solution how to accomplish this.

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RaTTuS
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Re: Multiroom audio system via RPi built-in FM radio transmi

Thu Apr 20, 2017 2:28 pm

you really don't want to do this - ,
you will cause far too much radio interference , and depending on where you are in the world you will get visits from the People in charge !
use bluetooth or a <£5 FM transmitter
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fkbreitl
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Re: Multiroom audio system via RPi built-in FM radio transmi

Thu Apr 20, 2017 2:57 pm

Why is the Raspberry Pi causing more radio interference than a cheap FM transmitter and how much?

Bluetooth will not work since its range is too short, it can only connect to one device, has sync issues, needs additional power adapters and its software setup is complicated.

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RaTTuS
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Re: Multiroom audio system via RPi built-in FM radio transmi

Thu Apr 20, 2017 3:05 pm

because it spams out a square wave and bleeds all over the spectrum..
https://www.aliexpress.com/item/Mini-Wi ... 13291.html
will be a lot cleaner
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fredoll
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Re: Multiroom audio system via RPi built-in FM radio transmi

Thu Apr 20, 2017 3:12 pm

I thought there was a solution with Pulkse Audio over the network ?

fkbreitl
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Re: Multiroom audio system via RPi built-in FM radio transmi

Thu Apr 20, 2017 3:30 pm

RaTTuS wrote:it spams out a square wave and bleeds all over the spectrum..
fredoll wrote:I thought there was a solution with Pulkse Audio over the network ?
Can you give more details or a reference for your answers?


fkbreitl
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Re: Multiroom audio system via RPi built-in FM radio transmi

Thu Apr 20, 2017 4:30 pm

Thank you! Looks interesting, but also a bit more expensive on the receiver side.

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RaTTuS
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Re: Multiroom audio system via RPi built-in FM radio transmi

Fri Apr 21, 2017 6:50 am

disclaimer on https://github.com/ChristopheJacquet/PiFmRds
other info on
viewtopic.php?f=63&t=138134&p=917345#p936815
there are other posts but a quick search does not find them ATM
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fkbreitl
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Re: Multiroom audio system via RPi built-in FM radio transmi

Fri Apr 21, 2017 9:28 am

Very interesting, thank you!

Unfortunately after setting up my 15 year old FM radio transmitter with a power adapter it also transmits the 50 Hz mains hum.

Are there any new (USB?) FM transmitters which do not have this problem or how can I avoid this?

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RaTTuS
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Re: Multiroom audio system via RPi built-in FM radio transmi

Mon Apr 24, 2017 7:07 am

because you asked nicely here's one I found on aliexpress
https://www.aliexpress.com/item/Usb-Min ... 80842.html
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fkbreitl
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Re: Multiroom audio system via RPi built-in FM radio transmi

Mon Apr 24, 2017 9:46 am

Thank you very much!
It looks similar to the the other one you posted last time.
How can one know if it doesn't have the main hums problem?
Is this just a guess or did you infer this from the buyer's feedback?
The other question regards whether I can use it while charging (i.e. while I leave the cable plugged).
I read about another receiver that this would not work.
Of course for that price it seems easiest to just order one to find out.

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