Electronics > Projects, Designs, and Technical Stuff
1200 baud data transfer over audio passband of cellphone. Is that possible?
TheUnnamedNewbie:
Audio on a cellphone tends to also be compressed in very specific ways that are optimized for voice (which is why the 'please wait' music with callcenters is so horrible). I suspect you will find it very hard to send any data through it as it too will be crazy deformed by the codecs.
sv3ora:
I have encountered this situation you mention, only on remote areas where there is no good signal, or when I used very old phones (1998 era). Dropouts of audio parts or "pixelated" sounds in some audio parts. I have not come across similar situations when there is a good signal.
Note, for FSK, audio amplitude compression should be less critical, as it is the frequency of the tones that matter.
TheUnnamedNewbie:
--- Quote from: sv3ora on October 29, 2019, 12:14:19 pm ---Note, for FSK, audio amplitude compression should be less critical, as it is the frequency of the tones that matter.
--- End quote ---
Don't most audio compression algorithms do a lot of stuff in frequency/wavelet domain where frequencies/wavelets that are considered secondary to the main few peaks are just removed?
ogden:
--- Quote from: TheUnnamedNewbie on October 29, 2019, 12:07:21 pm ---I suspect you will find it very hard to send any data through it as it too will be crazy deformed by the codecs.
--- End quote ---
Not true. Speech indeed is spoken *data*. Question here is how to modulate digital data such a way that speech codecs do not affect audio signal during transmission.
sv3ora:
--- Quote from: ogden on October 29, 2019, 12:30:12 pm ---Question here is how to modulate digital data such a way that speech codecs do not affect audio signal during transmission.
--- End quote ---
Precisely!
I think I am going to do the test with the MixW modem to see what will happen. We may come across pleasant discoveries...or not.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version