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GSM module recomendation

edi94

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Hi

i want to retrieve audio from GSM. i know if i use ADC it need a decent external ADC with i2s or something. and if i use module with i2s interface, the module price would be high. does anyone have a recommendation for me on how to get audio out of GSM module?
 

KlausST

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Hi,

Most GSM modules have simple audio input and output. ...and don't need external ADCs. Even SIM800.

So I guess: either you didn't do a search, or you hide requirements.

Klaus

Btw: I2S ADCs are not necessarily expensive, either.
 

edi94

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sorry, may be i am not telling the whole requirement.

i also need to send an audio through GSM module as well. so i need external DAC as well. and do a little processing with the audio data.
i did a few search before i asked on this forum. and i came across SIM800 as well. but i found this https://forum.arduino.cc/index.php?topic=625467.0
some mention its not working/supported for some reason. i havent bought the module yet. so i need a recommendation of what type of modem that support this. if anyone has ever try to read audio I/O out of modem.

i know I2S ADC is not expensive. but i search in one package build with ADC and DAC is a bit expensive.

and why i need this recommendation is finding/buying a component is not easy in my country. i might need a few week or month to get them delivered. so i need to buy for both system i guess. one with external dac/adc and one using I2S modem. can you give me an advise which modem should i use and ADC/DAC that have enough power to read and write audio?
 

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Hi,

Before you asked about retrieve audio.
Any voice call is sending and retrieving audio, thus most modems will do.

Now you want to process the audio data - at least it seems so.
But processing is completely different, it can be from simple digital volume control up to FFT and back or MPEG compression...
Also data width and sampling rate plays a role. A very wide range...

Klaus
 

edi94

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Hi Klaus

yeah, any modem will have analog audio output and input. there wont be a complicated processing. may be just recording and play it back to modem. sure i need external MCU so i am considering modem with I2S interface so i only need a little time to read audio data cause the bandwidth I2S is high. but most modem with I2S i know is expensive for this kind of project. i read a few about SIM5360. but here its cost above $100 each. do you know any cheap modem with I2S? or do you have a better idea to get this done?
 

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Hi.

More confusion, more question than answers.

Now you say you need an external MCU. With or without I2S?
If with I2S: then there are 3 devices with I2S. Modem, ADC, MCU. Who is the I2S master?

Then you talk about little time because of high bandwidth. I2S usually is a continuous stream. There is nothing such as "little time".

I'm really confused now.

Klaus
 

edi94

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Hi Klaus

as far as i know any modem will need external MCU, for example to answer the call in the first place, then get the AUDIO data. unless we use programmable GSM module like A9 Ai Thinker ( i am planning on buying this type ) when you can control all the process inside. what i need is a bridge between MCU and GSM modem. i was saying i am going to need either I2S interface or using ADC with I2S to microcontroller.

if there is a cheap GSM module with I2S output, then i don't think i need external (decent) ADC/DAC to get audio data. but if i none of them were cheap, then perhaps i really should considering ADC/DAC with high speed interface like I2S cause i need to retrieve the audio in and feed the audio out.
 

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Hi,

Not answering questions will not help. It will not help us and it will not help you....
Provide clear and complete informations. Draw a sketch..

Klaus
 

edi94

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i am not sure at which part you don't understand. i want to read audio from GSM call and write audio during call. that was the main goal

in order to do that, there are a few option i know. two of them are using i2s interface (digital data) and using speaker&mic(analog data) from module.

so back to main question. is there any recommendation for cheap GSM module with digital audio interface?
or recommendation of ADC/DAC that has enough speed to do this
 

KlausST

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Hi,

still very unclear for me. Maybe I´m too stupid .. but you don´t spend much time and effort to clarify...
So maybe an audio CODEC is what you need.

I tried with 5 posts to get clear informations or a simple sketch...I´m out. Good luck.
 

edi94

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Hi Klaust

I am sure you are a great engineer. we just not in the same page. Thanks for trying to help. really appreciate it. and you were right. i will need audio codec in order to feed digital audio data to modem and read audio data from modem. but usually some modem has I2S interface so we can process audio data digitally. i mean, if we want to make desktop application to make a phone call, then we can just use USB I2S for that. instead of using speaker and microphone. that way we can play WAV, MP3, any audio format easily.
 

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