# Tag Info

74

You can't use a EEPROM or any other storage means that is digital without first converting your signal to digital. Using a microcontroller is the obvious and simple way to do that. However, if you really want to satisfy your inner cave man, acquire one of these: This stores analog data from a few 10s of Hz to a few kHz. You'll have to consult some clay ...

49

You are confusing band with bandwidth. Band - The frequency of the carrier. Bandwidth - the width of the signal, usually around the carrier. So a typical 802.11b signal may operate at a 2.4GHz carrier - the band - it will only occupy 22MHz of the spectrum - the bandwidth. It's the bandwidth that determines the link throughput, not the band. The band is ...

36

No, you can't store an analog value as-is on a digital storage medium like an eeprom or an SD card. You could do an analog-to-digital conversion (using an appropriate chip) to convert your analog to digital. For the next step, writing to an SD-card practically requires a processor. If you really don't want to use an MCU you would end up designing and ...

19

The bandwidth of the Wifi signal is nothing like 2.4GHz-it's 20 or 40MHZ. What you are suggesting (baseband 2.4GHz) would use up the entire EM spectrum to 2.4GHz for a single channel of communication. As you can see from this, it's already pretty well used for various other things: Essentially, the 2.4GHz carrier is wobbled a little bit to send data and ...

19

The answer is "It all depends". What is the load on the DC? If it's very noisy inductive loads, you're going to have noise on the DC line, and it might be considerably more than you'd think What is the signalling rate on the data lines? Faster rates are vastly much more sensitive [EDIT] What line encoding have you got? Anything differential, such as RS-...

16

If you feed something to a UART port of a microprocessor you must follow the UART communication protocol if you want the microprocessor to understand what you are feeding it. You need to embed each ASCI character into a UART package that contains a start bit, a stop bit and possibly a parity bit, a lot more information is available on the UART Wikipedia page....

16

Aluminum oxide is stable, hard (as sapphire, because it IS sapphire, aka alumina, Al2O3), and nonconductive. Oxide grows spontaneously on contact with air, so an aluminum electrical connection is often unreliable. Welding works, and some (fluoride-based) fluxes can allow soldering, but for crimp connections, you need antioxidant pastes and/or odd ...

16

What you are trying to do sounds like logging. There are lots of data loggers out there sold commercially. If you want to log voltage readings you can try googling "voltage logger". Such devices write a log file to a storage device (sd card, thumb drive etc.) from sensor readings. Technically this uses an MCU internally. But you never see the MCU, you ...

15

You need three things: an amplifier (sorry, unavoidable), an ADC, and some digital storage. With the quality of modern op-amps, you totally do not need to be concerned about noise and distortion; you can easily achieve >100dB SNR. Nonlinearities in the hydrophone itself will be a far worse source of distortion. If you don't amplify the signal, you will be ...

15

Basic parameters To summarize, you want to log a analog signal of up to 100 mV amplitude at 10 kHz sample rate. That's quite doable. You want to collect data for up to "weeks". Let's see how much data that is. You didn't specify resolution or signal to noise ratio, but let's say 12 bits/sample, or 1.5 bytes/sample. That's 15 kBytes/second = 900 kBytes/...

15

Actually, the answer to your seemingly simple question is more complex than you'd readily believe! The short answer is that one signal at a time can be passed through a single signal wire, in one cycle. The amount of data that symbol represents depends on the protocol used. The long answer is that: 2-state protocols, like OOK (On-Off Keying), pass only one ...

12

Your clock signal is edge-triggering, in your examples on the positive edge. You can tell because the data has to be stable a short time before the clock edge (setup time), and if the clock would latch on the falling edge it would coincide with your data changing. Except for the setup time there are few constraints: the clock may stay high as long as it ...

12

In order for the 2.4 GHz Wi-Fi signal to avoid trampling on the 900/1800 MHz mobile phone signals, 100 MHz FM signals, and a whole vast range of other signals, there is a hard limit on how much the signal is allowed to differ from a 2.4 GHz sinewave. That's a layman way of understanding "bandwidth". The point of having one transmitter at 2412 MHz and ...

10

The answer depends on your definition of "directly". I could imagine the following setup (far from "direct", but without an MCU): Target memory: parallel EEPROM ADC with an (eg.) 8-bit parallel output A set of registers to make a counter Timing chip (eg. NE555) Another EEPROM that would be programmed with a state machine + some gates that would basically ...

9

The carrier frequency used by Wi-Fi is 2.4 GHz, but the channel width is much less than this. Wi-Fi can use 20 MHz or 40 MHz wide channels and various modulation schemes within these channels. An unmodulated sinewave at 2.4 GHz would consume zero bandwidth, but it would also transmit zero information. Modulating the carrier wave in amplitude and ...

9

Standard audio cassette tapes are analog. There are some digital formats, though, including DAT tapes. Standard tape heads are much too large to address individual domains, so the signal is basically encoded as the average domain orientation in all the domains under the head at a given moment. I believe the fact that the domains are discrete is the source ...

9

To put a simple summary to the existing answers: Aluminum isn't commonly used in wire because while it is a fair conductor, it makes a mechanically poor wire. Rdtsc gave a very good link in a comment. That list is a run down of all the problems you will encounter when using aluminum wire. The short of it is that aluminum has poor mechanical properties ...

9

The reason you can't find a scope with enough channels is because you're looking for the wrong tool. Scopes are best for analog stuff, and ones with more than 4 full-featured channels are rare. Each channel on a scope has a relatively complicated, and thus expensive, high-bandwidth low-noise amplifier, so a scope with 50+ channels would be extremely ...

9

The current drawn over a DC power supply is usually not constant. Changing current results in a changing magnetic field. So it might be necessary to separate power and data, it might not be. In USB or PoE Power and data are not separate. In SATA it is. So you might need to take measurements and either separate the cables or get a better shielding between ...

9

These chips are used as part of Apple's MFI Certification program. Basically, you have to be a certified developer to sell lightning cables. If you buy a lightning cable from a reseller, you may receive a notification on your iPhone like This accessory is not supported every time you plug in the lightning cable. The pop-up is quite annoying. Your iPhone ...

8

Mostly the same stuff as for rigid FR4 boards. Material will often be polyimide or polyester. Of course you'll want to bend the PCB, so check with the manufacturer what the minimum bend radius is for different thicknesses. In general this radius is small, like 6 to 10 times the circuit's thickness for a double layer FPC, that's a couple mm, and shouldn't be ...

7

Physics Specifically the Shannon Information Theorem, which (loosely) states that the amount of information you can encode in a signal is limited by the bandwidth of the signal. In wireless channels bandwidth is constrained (see below). In wired systems, bandwidth is almost unconstrained (being limited only by manufacturing and cost issues up to 10's of gHz)...

7

A chip will behave normally as long as you operate it within the 'normal operation parameters' as specified in the datasheet. Most chips have only requirements about the minimum time between clock edges, and the setup time (data stable to active clock edge). Neither are violated by stretching the clock. In practice, a software-generated clock signal will ...

7

"Simple" is extremely hard these days. What you are looking at is a small computer in itself; the Broadcom chip (datasheet) contains an ARM processor and is an entire computer in itself to run the WiFi. The datasheet says that it speaks either SDIO or USB. The square pad on the board usually indicates pin 1, although that doesn't tell you what pin 1 means. ...

6

Noise is the determining factor. You first must start with the noise level of what your Accelerometer + Amplifier puts out, lets call this N for noise. Then you need to find what your accelerometer puts out at it's maximum, we will assume that this will be some RMS value and call it S for signal. Your SNR (signal to noise ratio) $=\frac{S}{N}$ The base ...

6

The slip ring is the most obvious solution, but it's prone to wear and noise. An alternative may be a videohead from an old VCR. They contain coils that act as a transformer to transfer the video signal from the magnetic heads in the rotating part of the head to the fixed part. Very quiet and low wear.

6

In general yes that is possible. For example a guy called Christopher Tarnovsky managed to tap the inner data paths of a Trusted Platform Module. He used acid to remove the encapsulation, rust remover to get rid of some mesh and then managed to probe the circuit and intercept internal communications. Obviously on such a small scale it is a non-trivial ...

6

Basically what's done is some 8-bit message words have two corresponding 10-bit code words. One of these has positive disparity (more 1's than 0's) and the other has negative disparity (more 0's than 1's). When encoding you keep track of the running disparity. If the running disparity is positive and the next input octet gives you a choice of code words, ...

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