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24

Simply because having more bands not only requires a very versatile chipset, but also extensive antenna design! To explain: It's impossible to make the perfect antenna for all frequencies, but you can make "compromise" broadband antennas. You can do that in a lot of ways, but in the end, you need to integrate those into a mobile device. And that's where it ...


17

Commercial line out specification is to be able to drive 1 milliwatt to a 600 ohm load. For a sine wave, this means a voltage of 0.77 volts RMS (2.2 volts peak-to-peak) and a current of 1.3 milliamperes RMS (3.6 milliamperes peak-to-peak).


13

Check out: http://en.wikipedia.org/wiki/Line_level The most common nominal level for consumer audio equipment is −10 dBV, ... Expressed in absolute terms, a signal at −10 dBV is equivalent to a sine wave signal with a peak amplitude of approximately 0.447 volts, or any general signal at 0.316 volts root mean square (VRMS). ... There is no absolute maximum,...


13

This is the data I can share with you after having run my own set of experiments and having search (extensively) through the Web for other people's real hands-on tests. I have discarded / omitted the data which I have been unable to reproduce: The impedance of the standard Apple miniature hands-free microphone, the one integrated with the headphones they ...


12

Unfortunately there is a lot of "audiophile" nonsense around headphone amplifiers and headphone impedance. Probably the top 5 results for "headphone impedance" on Google are just wrong. This site contains some useful information (though a lot of it is wrong too). But anyway if you look at the graphs which I assume are correct, you can see that in the audio ...


11

None of the smartphones today have dedicated GPS chips in them, they only have a GPS capability that stems from byproduct features of the modem chips. That's not true. GPS functionality in phones is done either with a dedicated chip, or with a dedicated GPS receiver within a System-On-Chip (which is effectively the same as having a dedicated chip). ...


10

Passing digital data via ultrasound is a lot more tricky than you might think at first glance. We are doing this in a product currently in field trials, but when we started designing there was very little information about it out there. Most of the problems come from the fact sound propagates slowly (about 3ms per meter), and it can reflect and echo around ...


8

This is a no-brainer really. The 36kHz is the carrier frequency, the baseband signal is well within the audio range. Use an integrated RC receiver, it would be silly to make your own. They combine AGC, bandpass filter and demodulator. I've used Vishay devices, and I'm quite satisfied with them. There's a number of protocols, but RC-5 is the most ...


8

Okay, it seems to be simpler than I originally thought (I should not have read the marketing first) I now realise most touch screens use mutual capacitance between a grid of electrodes (I was thinking of the case of a single touch pad initially) I think it's just a piece of foil. With mutual capacitance any conductive object should disturb the field, however ...


7

There is no hard-and-fast rule for headphone jacks; be it a laptop, MP3 player or a regular stereo system. I would say that a typical headphone output adheres to Line Level specifications, although for headphones they become more of a guideline than a stringent set of figures. As you have already discovered, different devices have different output levels. ...


7

You want a compass. Like the normal analog ones, it senses the orientation of the earth's magnetic field.


6

This is in addition to PkP's answer. While "line level" audio is typically 1 mW into 600 Ω, and this comes out to 1.1 V p for a sine, audio is far from a sine. Even if the spec is adhered to and you only get 775 mV RMS on average, the peaks can be considerably higher than 1.1 V. It is generally good to accept and handle without distortion peaks up ...


5

Apparently you have a audio signal with 3.3 Volt peak to peak amplitude and want to couple that into a "microphone" input of some other audio device. Microphone inputs are meant to take the very small signals produced by microphones. These are often 1 mV or less, with peaks maybe a few mV in normal operation, although this depends a lot on the microphone. ...


5

Look into Project HiJack, which establishes 2 way serial connection to the iPhone via the earphone port and harvests power! The source code is open source. They use Manchester encoding for modulation, a brief analysis of their code is on my blog.


5

The iPhone uses LIS302DL, capacitive. The Samsung Galaxy 2 uses SMB380, capacitive. The HTC Touch Diamond uses KXSD9, capacitive. Some market share information on MEMS devices.


5

The link in Michael Kohne's comment is the answer: The iDevice needs to see a resistance in the neighborhood of 5k between the microphone conductor and ground. That tells it that a microphone has been plugged in. If it is a direct short, it thinks a headphone was plugged in. Open circuit means nothing was plugged in. The exact value is not ...


5

Generic: Connect each button between one of the stereo output channels and the microphone input, along with some resistors for attenuation and possibly a capacitor for DC blocking (suitable audio input circuits have been published, you can search for them as readily as I can). Have your app output an audio tone of different frequency on each of the left ...


5

Not having used said app I believe it is a master of assumptions and averages. The far field of a transmission line with two opposite current conductors is essentially zero. However the near field on anything other than a solid screen co-ax will always have a unbalanced component around it. The maximum unbalance will be when the two current conductors are ...


4

I expect you are right about what the wires are. You should check with a voltmeter though to make sure. Ground should have the lowest voltage, power the highest, and the return audio somewhere in between although it may be almost the same voltage as the power but at a higher impedance. If you load the audio line with 10 kΩ or so, it should drop a ...


4

I still find this question confusing. Do you want the frequency of the carrier in the IR signal to map into some property of the generated audio signal? If yes (and it would be hard to imagine what you would need that for), tell us. For that, you need a circuit quite more complex than just an integrated IR receiver. If no (so, you just want to decode IR ...


4

Very small scale, undocumented parts. You'd need smd desoldering tools, and then spend days on trying to figure out how it maybe works. Not worth it.


4

The D+ and D- (I think you made a typo in your question) lines must be held to 2.7 V to support 12 W charging. Unfortunately I don't have access to the Apple MFi Specification (which would be the best source), but this forum entry and subsequent answers by TI employees indicate that 2.7 V is the correct value. Furthermore, this schematic below uses a ...


4

Taking the Android specifications, you need 2.2Volts in series with a 2.2K resistor. Like this example from the Android specs: You can probably use 3V (2 AA Cells of 1.5V each.) 5Volts through that 2.2K probably won't hurt anything either. Example for using Scope: simulate this circuit – Schematic created using CircuitLab


4

How a device interacts (if at all) depends on the device (for example: a phone) and the charger. Problem is that there is no universally applied standard for USB charging so many manufacturers "do their own thing". I found here an application note by Maxim. From this the following picture confirms that chargers can be different in how they treat the D+ and ...


4

That's not going to work. An iPhone needs a minimum of 5V / 500 mA to charge. This comes out to 2.5W, which is five times higher than the output of your TEG.


4

Define "heavily damaged". If the screen is crushed just replace it with a new screen and digitizer, swap out the battery, and it may well power up perfectly fine, you can enter in the pass code and go from there. Any cell phone repair shop can do that for less than $100 in a few hours. You don't need the charging circuit, the microphone, the camera or even ...


3

You might want to take a look at this and check if you have the same config. http://www.wisebread.com/build-a-cable-to-control-your-android-phone-while-you-drive I'm sure android and apple are the same kind (I've used them interchangeably) though samsung android phones have two rings swapped.


3

The arduino would need a higher voltage. Use an non inverting OP amp on the line which should bring the voltage to about 2ish Volts, something which is better for the arduino. :) http://www.instructables.com/id/Arduino-Audio-Input/step3/Non-Inverting-Amplifier/


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