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3k views

Why are digital oscilloscopes still so expensive?

I'm a beginner in hobby electronics and I am wondering why digital oscilloscopes are still so expensive? In times of cheap GHz CPUs, USB 3, ADSL modems, DVB-S receivers, blu-ray players which all of ...
4k views

How do digital oscilloscopes achieve such high sample rates?

From the perspective of data capture, how is this achieved? If I wanted to implement a home-made digital device to capture high frequency analogue signals, what are my options? So far, I've only come ...
11k views

Maximum sample rate of Arduino Duemilanove?

G'day all! I have an Arduino Duemilanove hanging around spare at the moment and thought I might try a few audio interfacing projects. I'm just wondering what sort of sampling frequency I can achieve ...
2k views

Why is the Nyquist data rate lower than the Shannon data rate?

In the book Computer Networks, the author talks about the maximum data rate of a channel. He presents the Nyquist formula : C = 2H log$_2$ V (bits/sec) And gives an example for a telephone line : ...
872 views

What's the difference (electrically) between AC- and DC-coupled sampling circuits?

I've noticed that in analog signal acquisition hardware you see two paradigms: AC-coupled and DC-coupled. Typically AC-coupled hardware is less expensive, and basically has a 20 Hz high-pass filter ...
744 views

Is it possible to increase the resolution of an ADC by supersampling on a PIC24F ADC, which has 10 bits of resolution and is implemented using a successive approximation engine? Speed is not critical ...
707 views

Equivalent time sampling on microcontrolers

I must admit, I don't know too much about analog electronics but I am keen to know if it possible to construct an equivalent time sampler (ETS) using the A/D's on a micro. I hope this question isn't ...
71 views

What should be the sampling frequency for a square pulse train in a DAQ system?

Since a square pulse has very high harmonics how to obtain a good resolution of pulses? For example if we have pulse train around 500 Hz could we treat it as a typical analog signal and sample it with ...
62 views

What is the relation between multiplexing and the sampling frequency in a data acqusition system?

There is a data acquisition board recording analog signals from 10 channels with multiplexing. If one wants to sample each channel with for example 2000Hz and the number channels is 5 should the ...
1k views

How to sample audio at Nyquist frequency with MSP430F5438?

I want to: Input an analog audio track Using the microcontroller ADC, convert it to a digital output Then have the microcontollers/boards timer sample the data at selected intervals Resample the ...
168 views

How to measure, with timestamps, changes in the received luminance?

I'm working on a project that is in need of some testings to validate it. I need to make some readings of luminance from a light source and store this reading with a timestamp (milliseconds ...
283 views

8~16 PDM digital microphone + what processing? = beamformer!

I am researching on a project about sound source beam-forming. I'd like to build: 8~16 digital microphones into one 2D(circle)/3D(sphere) PCB to form an array with an equal separation of each mic 3cm ...
580 views

Wifi limitations

What are the limitations of using wifi where you have say 30+ clients/devices pushing compressed audio (flac)? bitrates: ~384 to 768 kb/s (44100 x 16 x 1 to 48000 x 16 x 1) * ( 0.5 to 1.0 ) (sampling ...
1k views

How can I find a specific frequency after doing FFT?

I have some samples from an SDR that I run through FFT and I want to detect the presence of a specific signal, exactly 148.369MHz. The maximum sample rate of the device is 2Mhz, this is just ...
1k views

Highest ADC input signal frequency for atmega8?

I am trying to make a simple project which involves acquiring some data from the adc of atmega8 chip and then sending that data to UART. But I cannot figure out what would be the maximum limit of the ...
200 views

What should I be using to amplify a heat flux and load cell signal?

For my senior design project, we have various sensors (Thermocouples, Heat flux sensors, load cell) plugged into our DAQ. We are using LabView and some National Instruments devices (ugh) and ...
226 views

Interference beetween ADC samples with XBee and photoresistor

I'm using an XBee serie 2 module for sampling the values of three sensors, a photoresistor (LDR) a moisture sensor and a temperature sensor (LM35). When there is no brightness the photoresistor has ...
559 views

PIC analog to digital converter to measure more than one battery voltage (with different grounds)

I'm trying to build a circuit that can scale down several lipo batteries (5 cell) up to 22V max to be safe to either 3.3V or 5V for measuring with a PIC microcontroller using the analog to digital ...
117 views

Considering Delta Sigma ADC. How to set an arbitrary sampling frequency with ADS1675

I have been reading about what delta sigma ADC (DSADC) is and if they can help me in my project and I think they will. The oversampling reduces the requirements on the analog anti-aliasing filter and ...
546 views

Measuring low current at very high speed

I have a circuit with a very-low-power Jennic JN5148 module with microcontroller and 2.4 GHz radio, and some low-power sensors. I have to measure the supply current of all these components, in an ...
232 views

Periodic graph in frequency domain

Why is that the frequency domain has the same shape all through out? Look at figure b
55 views

Nyquist sampling rate with real and imaginary aliasing

I need to calculate the Nyquist sampling rate of the function $x(t) = cos(6t)-sin(5t)$. By definition the Nyquist sampling rate is the minimum value of $\omega_s$ that yields no aliasing ...
79 views

How can you recieve a 6 GHz signal with only 64MS/s ADC?

The Ettus Research Software Defined Radio B210 has a range of 70 MHz - 6 GHz, a Bandwidth of 56 MHz and its maximum ADC rate is 61.44 MS/s. Doesn't Nyquist theorem state that the sampling rate should ...
32 views

Sampling phone line

I want to connect phone line to my PIC's ADC to sample signal changes without interfering the line. Human voice and DTMF signals are all under 4kHz level. So, I am hoping that any 18F PIC can do ...
155 views

what is the difference between sample method and sample and hold method

I want to know what is the difference between sample method and sample and hold method ,and why are these two methods important to study analog to digital conversion and its reconstruction back to ...
58 views

Undersampling of a non periodic pulse signal

I am starting getting familiar with electronics, consider me as a newbie.. I am facing a sampling trouble with my DAQ system. I have a non periodical pulsed signal with a separation between the pulse ...