I'm going to receive audio data from a device and handle through mobile's headphone jack. but my data has low frequency about 1Hz and depending what i found its too low for this port, I searched about 3.5mm headphone jack frequency range but couldn't find anything! what is your suggestion? USB port can solve the problem?
3.5mm headphone jack frequency range
mobile
Related Solutions
Headphone jacks have extra contacts inside, which act as switches. The the drawing below, pins 4 and 5 are intended for sensing that the plug was inserted. They are not intended for audio signal. When the plug is not present, the switche, which are formed by 2 & 4 and 3 & 5, are closed. When the plug is inserted, these switches are open. The plug flexes 2 and 3 slightly, and they break contact with 4 and 5. You could insert a 3.5mm plastic rod [a dummy] into the jack, which will open the contacts, and the phone might think that earphones are plugged in.
Source: datasheet for a typical stereo jack.
If you must light your led without an external supply you could consider a small audio stepup transformer.Perhaps something out of a dead transistor radio.Otherwise you could build a diode pump that say quadrupled the voltage.Use shottkey diodes for your diode pump because they waste less voltage .Use a red led for your experiment because they need less volts than the other colors.
Best Answer
Your question is very nearly incoherent. You do not say (clearly) whether you want to put data into the cell phone and analyse it there, or whether you are going to send data out of the cell phone to be analysed by an external system.
Regardless, certain parts of your question can be answered.
To work around the limitations of the cellphone audio, you would be better advised to modulate the data on to an audio frequency that the phone can handle - in the middle of the speech band is probably best, so 1200Hz to 1800Hz. You can find plenty of data on the internet about frequency shift keying (FSK) or phase shift keying (PSK) for transmitting data across audio systems.
If none of that made sense, then you have a long way to go before you begin working on your data transmission. Read up on things. Define your data format and data rate. See what you can come up with for ways to achieve your goal. If you get stuck, come back and write a better question - and consider telling us what you are trying to do, as someone here may have done it already and can point you at a better way.