I want to make something with picaxe that listens to any noise then transmits it wirelessly to another picaxe unit that

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ZebH
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Joined: Thu May 12, 2016 4:50 pm

I want to make something with picaxe that listens to any noise then transmits it wirelessly to another picaxe unit that

Post by ZebH » Wed Jul 11, 2018 2:05 pm

Hi everyone,

I want to make something with picaxe that listens to any noise then transmits it wirelessly to another picaxe unit that takes what it has received and transmits it through a speaker.
Is this possible?

Any help would be great.
~Zeb

Liam
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Location: Christchurch
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Re: I want to make something with picaxe that listens to any noise then transmits it wirelessly to another picaxe unit t

Post by Liam » Wed Jul 11, 2018 2:27 pm

Interesting question. I think the PICAXE might be too slow for audio sampling.

An arduino, maybe.

You can play audio using a MP3-TF-16P with an SD loaded with mp3 files. unsure how you would go about recording it. Possibly we need to look at raspberry pi with a wifi or bluetooth connection as its a heap faster than picaxe serial :)
Liam Beale
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www.phoenix-tech.co.nz

joe_ivp
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Joined: Sat Oct 08, 2011 4:50 pm

Re: I want to make something with picaxe that listens to any noise then transmits it wirelessly to another picaxe unit t

Post by joe_ivp » Thu Jul 12, 2018 11:07 am

Hi Zeb.

It would be possible, and you could work out the limits to find out what audio quality is possible.

There are several techniques to sample audio and transmit data in an efficient way, some of which are possibly beyond the capabilities of a PICAXE, as they involve fast mathematical functions

But just to keep it simple .......

The PICAXE should be capable of sampling at twice the highest audio frequency you want to transmit.

This is known as the Nyquist Rate, https://en.wikipedia.org/wiki/Nyquist_rate

eg if it was speech, up to around 4kHz, then 8k samples/sec.

Now you have to shift the data out. 8k samples/sec at 10-bit will create 80k bits/sec, so the transmitter will have to be at least that fast. IR or laser could do it. The really cheap 433MHz Tx/Rx pairs are only good for 10kbps (at the very very most), there are faster, more expensive modules (Adafruit and others running at 900MHz or 2.4GHz).

The tricky bit is the digital-analogue conversion at the receiver. If you don't have a dedicated hardware DAC (some micros do) at the receiving end then it can be done other ways.

I'll leave you read this example of what's possible and involved with low bandwidth

https://www.romanblack.com/BTc_alg.htm

Google audio transmission using rf module, such as

https://www.edaboard.com/showthread.php ... ansmission

Joe

~ Andrew
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Joined: Tue Apr 03, 2018 4:35 pm

Re: I want to make something with picaxe that listens to any noise then transmits it wirelessly to another picaxe unit t

Post by ~ Andrew » Tue Jul 17, 2018 9:26 pm

Yup, you will need something more sophistocated than a picaxe. The most you can do typically is just 'Detect' noise. Even if yoou cranked up the clog rate of the picaxe you would not be able to get much "fidelity" as you need to sample at 2x the highest audo freq to get even clunky telephone type sound.
Then you are going to need some front end amplification and possibly audio compression circuitry...

To Process, then Record than send (a LOT) of data to another device is a bit tricky but an interesting concept. I would use Pi and say USB microphone and use a LAN to another Pi. Pi have the advantage of good media handling and can run anything and have a desktop environment that makes life easy.

~ A

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