- This topic has 4 replies, 2 voices, and was last updated 10 years, 11 months ago by AJISH ALFRED.
April 25, 2012 at 3:04 pm #1774mosaabParticipant
i have a project for designing a digital transmission circuit using pic18 microcontroller and then modulate the signal with any kind of digital modulation like ASK , PSK … etc
data will be sound from a mic but i don’t know where to start which one of the pic18 family will suitable for this project , which mic i should use and how to interface it with the microcontroller , which antenna will be used to transmitt the signal also how will the microcontroller will be programmed
thank youApril 25, 2012 at 3:32 pm #7547
nice project idea..
I recommend you to use pic18f452. It has 8 bit adc. Use a carbon mic. Put adc in continuous mode and you will get sampled values of analog voice signals in the adc register. Send each sample value to the serial port, where you can use a simple rf module like tws434 (ask or fsk). The baud rate should be less than 3000.
At the receiver end use a rws434 and connect the data pin to the serial port. write the serially received 8 bit value to any output port for 8 pins, which are connected to 8 bit dac. If everything works fine, you will get the transmitted voice at the output of dac.
Complex coding and circuitary required. All the best..April 25, 2012 at 4:55 pm #7548mosaabParticipant
thank you for help , i didn’t understand the thing about sending each sample value to the serial port
can you explain in a little details and if available i need a shcematic for such a circuitApril 27, 2012 at 12:57 pm #7553
I’m glad to know that you are interested in the idea which I’ve posted. This is the basic block diagram
| mic |
| MCU |
The built in adc of the mcu take each samples of the continuous analog signals from the mic and convert it into descrete digital values. You can get the digital values at each sampling time directly by reading the register of adc. Send these values to the uart of mcu, at a baud rate less than 3000. Input of the transmitter module is connected to the Tx pin of the uart via a max232.
>5| DAC |
| MCU |
___________________________________ | |
The transmitted bits are received serially in the receivers uart, from there the digital values are read and fetch to any 8 output pins. Use a dac at the output to generate analog equivalent of transmitted signals. Amplify and fed to a loud speaker.
It is just my idea only. I recommend you to collect all the available details related to the project before proceeding with it.April 27, 2012 at 2:05 pm #7555
Sorry, I can see that the block diagram get distorted. It was very legible while editing, don’t know how it happened so while uploading. I actually tried to upload a .jpeg image, but that too din’t worked out.
Please copy paste it to any text editor and correct it yourself.
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