Questions tagged [data-acquisition]

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83 views

Why is this load resistor connected this way and what could be its value?

There is a potentiometer vane and the diagram includes protection components and looks messy, I simplified it by re-drawing as below: The circle R1, R2, R3 and the gap represents the vane's 10k ...
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4answers
798 views

Need a method for synchronization of galvanically separated microcontrollers

I would like to get some ideas for my problem. I have a HW which has a main processing unit (Beaglebone, host controller) which is connected to four galvanically seperated STM32 microcontrollers. All ...
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0answers
48 views

Why Do Pipeline ADCs have an “Overlap Bit”?

In pipeline ADCs, there is an amplifier after each stage that amplifiers the remainder of the previous stage by 2^(number of previous stage bits - 1). For example, if the flash ADC in the first stage ...
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3answers
251 views

How Can the Quantization Noise of an ADC be Measured using the Digital Output?

The ADC quantization noise is the error signal generated by rounding the sampled analog values of signal. Suppose that we have the digital output of an ADC, how can we measure the quantization noise, ...
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1answer
47 views

Sharing a single ground wire across multiple RTDs

Consider the following, simplified schematic for a single, two-wire RTD sensor: simulate this circuit – Schematic created using CircuitLab The two wires from the RTD sensor plug into pins 1 ...
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2answers
89 views

ADC / data acquisition board - general layout question

For one of my current projects, I am designing a small data acquisition board. However, I am currently not sure about the overall layout of the board. Here are 2 possible variants I came up with. ...
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37 views

Cutting off the negative part of my system acquisition signal

So I made an acquisition system for detecting a pendulum with a photodiode and an LED. Here is the system: LED/PD High Pass Filter Inverting AmpOp Notch Filter Buffer Low Pass Filter My goal is to ...
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2answers
71 views

What could be the reason for these bands in this data acquisition measurement?

Here is zoomed view of 16 channel The first plot looks very peculiar to me hence there are like two forbidden bands(looks like white lines as you see). This also appears if I plot any individual ...
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2answers
57 views

How to measure or estimate the phase delay between two analog input channels of this board?

There is a 16-bit data acquisition board with +/-10V range which multiplexes analog inputs and buffers the data to the PC. Specifications are given here (DAS6036 is the model in question). Now I need ...
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0answers
84 views

Whenever two system or sources are coupled they should have same current sink or common reference point (say ground). How to realize this in ECG?

Electrode (Ag-AgCl) are placed at different part and directly fed to positive and negative input of differential amplifier. How can we realize human body and amplifying system have same current sink ...
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2answers
134 views

Is only a firmware limitation the fact that some camera can't store photo in RAW format? [closed]

I was interested in understanding if from the point of electrical engineering storing the RAW data of the sensor directly into the memory of the camera require special hardware. Could be more ...
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37 views

Practical method to measure a data acquisition board's noise floor

Noise floor of a 16 bit system is usually within a few dB of 96 dB. And this is because 20*log10(2^16) = 96dB But I guess this is the theoretical quantization noise floor. So if this was the only ...
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0answers
43 views

Reliable methods to read data off a flash chip?

I'm trying to read data off of flash chips on a variety of embedded devices I have, and I'm currently using an FTDI FT2232H and flashrom (with soic-8 clips and probes) to extract the data as they are ...
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5answers
556 views

Processing ADC conversion result: DMA vs Processor Registers

I have a periodic ADC conversion (every 50 micro-seconds) and I use the result to do some further calculations and update the PWM load registers. The ADC is triggered by the up-down counter of ...
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0answers
80 views

How can I estimate the minimum baudrate for a given bitrate?

My circuit performs data acquisition at 250 samples/s, 24 bits/sample and transmit this information to the local host (PC) through a bluetooth module that implements the UART protocol. As far as I ...
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0answers
45 views

Should I daisy chain start connect or wire separately?

This is related to field wiring schemes and interference. Sometimes tens of transducers are needed to be coupled to a single-ended data acquisition board's analog input channels where the transducers ...
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1answer
48 views

Is there a problem connecting PSU grounds to earth for an isolated signal chain in this scenario?

For a precision and simultaneous analog signal data acquisition; several force, temperature and acceleration transducer outputs are coupled to a daq board input channels through signal conditioning ...
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1answer
68 views

Are there any benefits to amplify the signal for this case?

A force transducer together with its amplifier designed for a full scale load such that it has -5V to +5V range as output. But it is only used with loads outputting -200mV to +200mV. A data ...
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1answer
100 views

Order of write and read in Microprocessor interfaced with ADC

An ADC is interfaced with a microprocessor as shown in the figure. All signals have been indicated with typical notations. Acquisition of one new sample of the analog input signal by the ...
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1answer
92 views

How to conclude the necessity for unbalanced to balanced signal conversion for this scenario?

This is a bit specific system related question about simultaneous data-acquisition for several transducers. Therefore hope you don’t mind for the long intro and the question. It would be too implicit ...
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3answers
554 views

Is star grounding sources necessary for this data acquisition system?

Several single ended output and PSU powered transducers are tens of meters apart from each other outputting 0 to 10V DC like voltages. Some are temperature transducers some are force transducers ect....
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2answers
36 views

Comparing two imbalanced signal transmission

Below shows a perfectly balanced system assuming cables are balanced and twisted: Im wondering if the transmitter is not impedance balanced, would a balanced receiver reject CM interference still ...
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1answer
87 views

Holding signal true for x seconds in LabView

I'm trying to create an automatic startup override system whereby when an ESD override button is clicked, a signal will be held true for 10 seconds overriding my ESD interlocks. This seems like there ...
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0answers
152 views

ADXL343 data read

I am using a ADXL343 accelerometer in one of my designs and I am getting strange readings from the device. Just to be sure, I would like to confirm that I am formatting the data properly. (I get the ...
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3answers
2k views

What is the “Nyquist” rate for sampling the derivative of a signal?

Background: I'm sampling the current through a capacitor. The signal of interest is the voltage across the capacitor. I will digitally integrate the current measurement to obtain the voltage. ...
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1answer
96 views

Re-wiring experimental apparatus: Questions regarding proper ground, DC power supplies, and precision instrumentation

The apparatus consists of a large metal spherical chamber attached to a metal table. There are two electrical enclosures bolted to the table legs. The chamber is outfitted with multiple servomotors, ...
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1answer
1k views

RS485 to RS232 conversion?

I need to connect a sensor that uses a RS485 transmission to RS232 or something I can read through the com ports on my data logger. I can't use usb ports or virtual com ports due to the program I am ...
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1answer
55 views

Scaling up NTC measurement through Multi-Channel Ohm meter

For a test bed, we want to measure temperatures with NTC sensors (~10kOhm at RT) for the range 10°C to 70°C. Our test machine accepts auxiliary signal through CAN-bus, so we used a Raspberry with a "...
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5answers
816 views

How is binary data 'split'?

If one computer sends data, for example 001101, how does the other computer know, where one bit starts and the other one ends? If you were just to monitor the change, you would get 0101, which is ...
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1answer
51 views

Wiring an on-off switch to the inputs of a daq

I have the following reed switch sensor: I need to connect this switch to counter input of this daq hardware. The only info is the following: How should I connect this to the counter-input? Any ...
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1answer
193 views

Data acquisition microcontroller approach

I'm prototyping a data acquisition device which interfaces with 64 discrete inputs; 32 analogue and 32 digital (user-configurable as either ON/OFF measurement or frequency/duty measurement). I'm ...
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1answer
54 views

How does isolation prevent input signals to float/saturate for differential ended inputs?

A differential ended input data-acquisition board has the following architecture: Here more information. Through screw terminals it takes the voltage inputs and each input first goes to a signal-...
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1answer
62 views

Tape archival data acquisition

I have some old tapes (the compact cassette variant) and an old Technics deck. I want to digitally archive these tapes as best as I can. The original deck is from the late 80s and contains a standard ...
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1answer
32 views

Investigating the cause of the drift for this system

A force-torque transducer data acquisition system is shown below: As shown in the above illustration, basically a six-axis transducer is powered and amplified by an interface electronics and then the ...
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3answers
174 views

Is there a need for buffering in this case?

.. will be updated soon (in construction with a more accurate information) If the ADC (or the data.acq device) have 100 kohm input impedance, how much accuracy would I lose? Do I need to buffer this ...
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1answer
53 views

Experimenting interference effects for different measurement systems

This is about for low level signals interference/noise being observed with single ended data acquisition inputs but not with diff inputs. Basically there are three data acquisition boards, where one ...
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1answer
108 views

Confusion with grounding floating sources to be used with a differential ended data acquisition board

Regarding this paper, I first tried to wire single-ended floating sources to a diff ended data acquisition board. But because of some power supply related issues and not wanting to make another ...
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1answer
135 views

Noise due to stray voltages in a data acquisition system

A single ended earth grounded data-acq. board on the left in the below illustration has inputs coupled by BNC cables coming from force transducer amplifiers A1, A2, A3, A4 as shown on the right: If ...
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1answer
360 views

How can I transmit a TTL signal to a computer?

I am designing a data acquisition system including a sensor that outputs a TTL pulse signal (3 wires: power supply, common, and signal). I am trying to determine how to send this signal to a program ...
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1answer
128 views

How to explain this solution to the common-mode voltages?

One of my previous question revealed that a variable voltage test device's power supply which is an AC/DC adapter, and is SMPS type which causes common-mode voltages. A solution given by tying the ...
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2answers
200 views

Is this definitely common-mode interference and how can I model and filter it?

A test device which can output voltage between 0 to 10V by a knob is powered by a DC adapter which converts 220V rms(meaning 311V amplitude) 50Hz AC to DC. Device is not a commercial and its adapter ...
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2answers
899 views

Confusion with different recommendations about wiring floating single-ended output sources to differential inputs

I'm trying to configure single-ended floating sources to differential inputs of this data acquisition board which of course uses an instrumentation amplifier and have differential inputs. So I had to ...
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1answer
165 views

Using differential and single-ended inputs simultaneously in a data acquisition system

Below is the wiring setup I plan to use: Basically the black rectangle in the middle is this data-acquisition board which has 16 diff ended inputs. The blue rectangle on the left is a six-axis ...
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1answer
238 views

is it possible to design a SD 3.0 controller in UHS-ii/uhs-i mode using simplified specifications?

I've been for while looking to store a sampled data up to the rate of 30MBytes/s, an SD 3.0 host controller core in uhs-ii/uhs-i mode fits the requirements. i'm not planning to buy SD full spec and ...
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1answer
96 views

A question about differential ended settings for single ended inputs

Reading this documentation, what could be the reason to use 10k if one uses differential ended input settings for signal sources?: I dont know why they recommend 10k but I had 6 channels going to ...
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6answers
250 views

What is the need for amplifier stage in a data acquisition hardware?

Below is a typical data-acquisition block diagram: As you see above after the multiplexer there is an instrumentation amplifier IA. This IA stage can be shown in more detail as below: Since this is ...
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1answer
208 views

How to interpret this CAN bus data and find an equation?

I am trying to reverse engineer the data sent from an old CAN bus data logger. It sends a single ID which is selectable from a dip switch. The only bit of data I am struggling with is the RPM I plan ...
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0answers
50 views

Question about earth grounds for remote control of VFD via a DAQ system

A single-ended earth grounded PCI data acquisition board's analog inputs and outputs are controlled by a PC. The daq board has also analog outputs. One of the analog output is controlling the motor ...
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1answer
103 views

Wrong voltage measured with a DAQ in presence of a RC filter

I'm using a DAQ from National Instruments. Testing my LabView software I noticed that when I plug a 1.5V DC battery in the analog input channels if I connect an RC filter (R=56 kΩ, C=10 uF) to the ...
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1answer
282 views

Why are high-sampling-rate data acquisition boards so expensive? [closed]

An example would be the NI USB-6366. My guess is that it's primarily due to the analog-to-digital converter (ADC) since it should be the component responsible for the high rate conversion, even ...