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Emergency Sound Generation

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basalii

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I have designed an amplifier and microphane system for vehicles. I want to add emergency sounds like police, ambulance fire, etc. and air horn , normal horn. But actually i dont have any exprience about generate sound with stm microcontroller. I controlled other things on board with stm32f0. Does anybody could help me to how can i genarate these sounds?
 

audioguru

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Isn't it illegal in your country for your vehicle to make emergency sounds like a ambulance, police car or fire truck??
 

gophert

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Isn't it illegal in your country for your vehicle to make emergency sounds like a ambulance, police car or fire truck??
Maybe he makes sirens for ambulance, police cars or fire trucks (or has aspirations to make them).
 

gophert

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I have designed an amplifier and microphane system for vehicles. I want to add emergency sounds like police, ambulance fire, etc. and air horn , normal horn. But actually i dont have any exprience about generate sound with stm microcontroller. I controlled other things on board with stm32f0. Does anybody could help me to how can i genarate these sounds?

There are libraries to process WAV audio files. Just record the siren(s) you like (or pull them off the web or generate them with a waveform generator app, save as a WAV file and play it with the DAC on the STM32F

https://github.com/istarc/stm32/blo...ct/Audio_playback_and_record/src/waveplayer.c
 

basalii

New Member
Isn't it illegal in your country for your vehicle to make emergency sounds like a ambulance, police car or fire truck??
I do it for emergenecy cars not for my car. I know how to design anonsment system(amplifier etc.) but i have no idea for siren sounds.
 

basalii

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gophert

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Thanks for the comment. Firstly i think record and play audio files, but all siren devices generate the sounds and actually i dont know how i generate them.
Old "sirens" had motors that turn, compress air, push the air past reeds that vibrate to produce sound.

Newer either have circuits that produce a waveform (from an oscillating circuit, a Wave-like File from a computer-generated waveform, or a recording converted to an a diode file - amplify it through an efficient and directional horn-style speaker. Whether it is a
 

audioguru

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We don't know if your sirens produce only two frequencies (dee, doo, dee, doo) like in some countries or produce continuous sweeping frequencies up and down. In Canada, a fire truck also has a very loud low frequency blast.
 

unclejed613

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Thanks for the comment. Firstly i think record and play audio files, but all siren devices generate the sounds and actually i dont know how i generate them.
since the 1970s, these sounds have been made by cascaded voltage controlled oscillators (a "slow one" controlling the frequency of the audio one) the speed setting of the "slow" oscillator changes the warble rate. by changing the output waveform shape from ramps to square waves you change from a warbling sound (weeeeeooowwww) to a hi-low sound (deeedooodeeedooo)


what's really funny is when there's a movie set in a time before electronic sirens, like the 1940s or 1950s, but they use modern VCO based sirens... oooops.... please arrest the sound effects guy....
 

dontknowreally

New Member
I have designed an amplifier and microphane system for vehicles. I want to add emergency sounds like police, ambulance fire, etc. and air horn , normal horn. But actually i dont have any exprience about generate sound with stm microcontroller. I controlled other things on board with stm32f0. Does anybody could help me to how can i genarate these sounds?
Simple

Just use a UART controlled MP3 player..

Something like this:
https://www.dx.com/p/uart-serial-mp...Y-e7tzpPKiRBetld39EaAjW-EALw_wcB#.XBUPWBinyyU
 

basalii

New Member
I will try with playing wav file as gophert's recomendation. Now i search prafessional wav files for these siren sounds. When i find it i will share here maybe it will help someone.
 
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