# Questions tagged [statistics]

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### Lies, Damned Lies, and Statistics [closed]

I am measuring time of flight of an acoustic pulse over an arbitrary path length. How can I determine the statistical resolution of the device? So, I collect a load of readings over a path length of (...
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70 views

### UNI-T UT181A question: what is confidence interval used in the datasheet?

So the question is: https://www.batronix.com/pdf/uni-t/UT181A-Manual-English.pdf The manual has So if you are measuring perfect 50 Hz source you have resolution 0.001 Hz the values are in interval ...
209 views

### Mass paralled resistors for better tolerance [duplicate]

I hope this doesn't get people's eye rolling as a very rudimentary question... Here goes. I need a very, very precise resistor divider, say a 1/11 ratio. It doesn't really matter the ratio chosen. ...
• 409
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### How can I correlate a RSSI value to a distance measurement more efficiently?

I want to develop a trilateration algorithm using 3 fixed advertising beacons in different parts of a room and a mobile receiver which continuously gets the RSSI values of the 3 fixed beacons and ...
• 117
95 views

### Tolerance Stack Up Distribution

Suppose I've got a 2V source with 2% accuracy that I want to divide down to 1V using 5% resistors. One can easily see with Monte Carlo analysis that the worst case output voltage deviation is 7% I'd ...
72 views

### What is the statistical accuracy of a Reference Voltage based current source?

I would like to make a current source from a reference voltage chip (REF102). OPA277 is used as a buffer to pin the voltage at pin 4 to the bottom of the current setting resistor R. Hypothetically, if ...
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1 vote
195 views

### Number of data points needed for INL DNL estimation

In this article where ADC of pico pi is characterized, I found a part that I have never encountered in my study of mixed signals design: I don't understand how we number of data points needed is ...
• 261
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### How to monitor Ethernet packet loss real time on different connections?

For an embedded application we have a network with star topology, where we want to determine if there is packet loss for the different point-to-point (SMAC => DMAC) connections. We consider ...
• 579
1 vote
760 views

### Estimating shot noise - what's the origin?

If I have some photon detector, say a CCD, how do I estimate the error introduced by shot noise correctly? Typically, sources found on the internet say that the shot noise is the square root of the ...
• 121
1k views

### What is the physical significance of skewness and kurtosis of an eletrical signal?

I understood the mathematical meanings of the skewness and kurtosis. But when we calculate these quantities for a signal (say an electrical voltage signal), what physical meaning do they convey? For e....
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### Is measurement uncertainty 2 times standard deviation or 2 times standard error?

Textbooks and online sources often say the industry standard for uncertainty is given at a confidence interval of 95 %. This means out of 100 measurements, 95 would achieve the specified value and ...
50 views

### Suspicious definition of erlang distribution in Verilog-2005 spec

The \$dist_erlang function in Verilog-2005 takes an argument called mean. Some information about the ...
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### measurement errors: add up or cancel out?

Take an accelerometer, or a hall sensor, or a thermometer, or any sensor. It will have an accuracy, which means the readings will contain some error of this sort. My guess is that by taking a big ...
• 1,061
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### Why are different RMS noise sources added in this way?

I'm wondering why noise sources are added such a way their RMS values are added in square root of sum of squares fashion. For instance if the RMS noise values from three sources are X,Y and Z, then ...
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### Difficulty of implementation of this Rayleigh variate generator on simpler FPGA

For a university module we have been tasked with a 'research project' whereby we need to implement an FPGA non-uniform variate generator. I've identified one possible choice for the specific ...
• 869
1 vote
200 views

### Are there more (mains) electrical safety incidents in the United States compared to the UK? [closed]

Forgive me if this question isn't exactly "on topic" for this site -- it's a bit meta. I am an academic in the UK, and I occasionally design electrical devices that plug into "the mains" in one ...
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223 views

### PCB Thickness Variability

How much variability is there in the thickness of a standard PCB? Let's say I order a 1.6mm FR-4 board. Will the actual thickness range 1.5mm-1.7mm? 1.4mm-1.8mm? 1.59mm-1.61mm? What is the (...
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### Best method for determining tolerances based on production data

Say I am producing a wound coil which is ultimately going to be used in a colpitt's oscillator circuit. I measure the Ls and Rs of the coil, and then install it in a ferrite and then test it in the ...
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1 vote
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### Stochastic Processes wtih respect to the electric load demand [closed]

I am required to look at the statistics (stationarity, mean, standard deviation etc) of the electric load profile. I decided to use the load data for the IEEE reliability test system as it has all ...
60 views

### Random Error Waiting Time

Suppose that you have a design that has had an error after running 14, 18, and 20 hours. You're not exactly sure what is causing the error, but you make a change to the design that MIGHT fix it. ...
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208 views

### Second moments (i.e. E[X²]) for this WSS random process

I've attempted the question, please see attached image of my working out and solution to the question. My main question is how to go from the last line of my working out to “2Rx(0) - 2Rx(t)" in ...
• 105
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### How dangerous are LiPo batteries in phones, laptops, tablets? [closed]

Having recently read this question with its answers it seems like I should never ever charge my phone/laptop/tablet unattended. It also seems like I should always be worried about my devices exploding ...
• 321
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### Statistical accuracy of multiple resistors in series or parallel

I'm having a senior moment and would appreciate clarity. I'm working on an inverting amplifier design where I need to add low-pass filtering and a voltage clamp. Without the filtering and clamp, the ...
• 24k
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### Accuracy of RMS of sine measured from N samples of ADC conversion

I am sampling a pure sine wave for 1mS at 200nS conversion rate over a 12 bit range, getting 5000 samples. I need to know how accurately I can determine the RMS value of the sine wave. More generally, ...
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