hi all,

do U know a way I can convert sound into digital form (bits)? say..I want to convert some audio (from a microphone, for example) into a bit stream in order to transmit it??

thx

Transmit it how? Over the air?

Many RF transmitted digital signals are done with software.

I think he's looking for both.

If you are looking for a technique to transmit digital information over RF paths, first I suggest you educate yourself on how digital is transmitted via radio in the first place.

There are several techniques. I suggest you learn about Phase Shift Keying and Frequency Shift Keying. You should also learn about modems and digital signal processing.

The key here is MODEM. (Modulator/demodulator). To transmit digital over radio, the signal has to be modulated over an RF carrier. The frequency and bandwidth of the carrier must be high and broad enough to accomodate a modulation scheme with high bit rate transfer. Broadbanded transmissions are typically undesireable, so digital broadcasting at higher bit rates is typically done at at VHF or UHF or above where the higher frequency permits higher data throughput over a narrower signal. Slower speed data is also feasable at HF and some narrow mode voice techniques have been developed. Simple mono-voice can be efficiently replicated digitally with narrow bandwidth by sampling only the critical voice frequency range required for audibility. Lower end bass and high end treble can be elimated with L-C filtering, for instance.

Remember, you need a MODEM. A modem is a device that converts audio into digital, and vice versa. A computer soundcard can be used as a modem. The transmitted radio signal is actually high frequency shifts of audio frequency. The RF signal that the radio pics up is demodulated by the radio and the audio is fed to the computer soundcard, accomplished with an audio transformer typically to impedance match the microphone input to the radio. The signal processor in the sound card then converts the signal into digital format that the computer microprocessors and software can understand. This will then be converted back into analog audio, but now it will be recognizeable as a human voice or music or whatever through the computer speakers.

All of this can also be accomplished with special radio equipment with built in modems , microprocessors, and signal processors/soundcards. But it is much easier to just outfit a radio with a computer connection and utilize whats already there.

The computer needs software written to communicate with the soundcard and analyze the waveforms that the soundcard signal processor is recieving. The software must be able to convert the audio presented to it into a specific digital language and vice versa.

I suggest you get ahold of the current ARRL publication on digital communication techniques. If you would like to experiment with transmitting digital voice, there are plenty of amateur radio experimenters who can guide you and help you set up the equipment.

http://www.itu.int/ITU-R/study-group...tions/S4-1.pdf

Here is a brief presentation on various digital techniques from the ITU which governs international treaty for the RF spectrum.

If RF tranmission is what you are after, I am not sure what frequencies you plan on experimenting with, just remember that certain frequencies require a license and/or power limitations to legally operate. Also, experimental techniques are typically developed on higher frequency bands at low power where interference issues are less likely to occur, particular on amateur radio.

I highly encourage you to get a ham license if you plan on experimenting with digital data over RF.

Originally Posted by Sceadwian

The only thing he asked about was how to get an anlog signal from a microphone into a digital one, nothing else, anything else is inferring information the poster did not present.

Well, he did use the word transmit as well. It is difficult when posters ask such vague questions. My answer was framed in the context that he wanted to learn how to digitally transmit his voice. I offered a lot of information. If it is useful for him, great. If not, perhaps my time wasn't wasted if it helps someone else.

Next time I post, I will send it to your message box for editing and approval.

Just kidding!!! I don't really care. It was my time to waste typing it out...I enjoyed writing it down and sharing. Like I said, if he got anything from it, fine. If not, oh well. I shared my bit of expertise on the matter and if he wants anymore he can ask.

He may have not have asked exactly what I answered, but he certainly didn't ask anyone to stand guard over his post and decipher it for him either.

(Just messing with ya man)

Sorry if I came across in an ugly fashion. I tried to post lightheartedly

But the more I think about the OPs post, the more I question why someone typing on a computer likely equipped with a microphone input jack would ask if there was a way to transmit his voice digitally if he was referring to transmitting over cables. And if he was asking about that, as lengthy as my post was, at least I gave him the obvious tutorial on soundcards that he needed.

OK, I'm done with the late night debate session LOL. Good night.

i wnt to mitutoyo digital circuts

where i can get lcd disply for mitutoyo vernier

Originally Posted by Mr CCE

hi all,

do U know a way I can convert sound into digital form (bits)? say..I want to convert some audio (from a microphone, for example) into a bit stream in order to transmit it??

thx

get PYRO software and you can record audio from a microphone or audio device into digital files of either WAV or MP3 types. You can also display them.