# Questions tagged [signal-processing]

the analysis, interpretation and manipulation of signals

1,006 questions
Filter by
Sorted by
Tagged with
83 views

### Can we catch signals from a cellphone using an external device? [closed]

What if someone stole em waves from our mobile devices to listen to our conversations or get our OTP. Whatever encryptions they have they are just EM waves innit and they cannot be propagated only in ...
1 vote
54 views

### How do I generate a trigger signal from a periodic analog signal having varying amplitude [closed]

I have an analog signal detecting a periodic vibration of low frequency (<100Hz) and want to generate a pulse whenever the signal crosses a certain threshold. The challenge is that the amplitude of ...
• 11
59 views

### How do data acquisition systems work?

This is a theoretical question. All the signal processing electronic systems I have developed up to now have customized electronics to filter out unwanted noise. Because their electronic filters are ...
• 99
46 views

### SNR calculation

I want to calculate the SNR of the following signal (the blue signal): The signal peak value is: 0.0292 V The noise peak value is: 0.0012 V Based on the following formula: SNR=20 log(Vp-Signal/Vp-...
• 657
54 views

### Attenuating a signal from a eddy current sensor for an ADC

I have a eddy current sensor, in a 7200 Proximity Transducer System, with a voltage output of -18V to -24V. My ADC has a max input range of +10V. I need a way to step the output signal down so I can ...
1 vote
51 views

### IR pulse sensor : signal stops after a few pulses

I'm trying to make a pulse sensor based on this tutorial: https://makezine.com/projects/ir-pulse-sensor/. I therefore reproduced this diagram by replacing the LM354s with MCP6002s and without ...
188 views

### THD of two passive circuits

I am simulating the total harmonic distortion of two simple passive circuits. VIP_Test = Ideal Sine Wave. Goal is to find THD for Test1 and OP_VIN_Test. (THD is calculated with the thd function in ...
• 179
1k views

### DFT of a pure sine wave not showing ideal sine wave

I have a question with regard to the DFT of an ideal sine wave. This is my simulation result in cadence. I analyzed an ideal sine wave (from vsin source) and passed it through a dft calculator ...
• 179
1 vote
82 views

### Is this the correct way to make a bandpass filter?

I'm trying to make a bandpass filter for a low voltage noisy electrical signal coming from a K-Type thermocouple To identify the frequencies I would need to filter out, I make a spectrum diagram using ...
68 views

### Switching from time domain to frequency domain and vice versa in signal processing using FFT

I have a problem dealing with a real signal in time domain or in frequency domain when I need to do some processing on it in the dual or other domain via FFT or IFFT. I find myself dealing with a ...
• 369
268 views

### Anti-aliasing filter for 3.3 V ADC at 1 MHz

I am designing an anti-aliasing LPF for a 16-channel ADC on a custom STM32F415-based board. This design will ultimately be put on a car and used as a DAQ. I am planning on running the ADC with a 30 ...
• 33
115 views

3k views

### Do faster responding low-pass filters exist compared to a traditional RC filter?

Lets say you have a very short DC pulse that has some sinusoidal noise in it. But the duration of the pulse is very short...maybe 0.5 µs. For an RC lowpass filter to respond quickly enough to begin ...
• 1,012
108 views

### Help with inverse Z transform

I have the following function on time domain $$f(t) = sin(100 * 2 * \pi * t)$$ and I need to get its discrete values when it's sampled at 1000Hz. After applying the Z transform and using T = 1/1000, I ...
1 vote
80 views

### Proof that two systems are equivalent

I was wondering if someone could help me with the proper answer for this? Below is the question and my solution. I was hoping for partial points but I don't know what can be marked partially correct ...
• 11
57 views

### Processing data from optical chopper to correct for drift

I have a time series measurement of light intensity where the signal is periodically blocked by hardware to provide a moving baseline to correct for drift. This looks like a square wave, where the ...
• 21
66 views

### Signal conditioning circuit for piezoelectric sensor

I am trying to build a signal conditioning circuit for a piezoelectric accelerometer. Due to the low output of the accelerometer, I intend to add a signal conditioning circuit to the output. My idea ...
• 913
44 views

### Z transform and the magnitude of Fourier transform

Would like to know if the graph of the magnitude in the picture I added is correct. Should I address the other pole?
34 views

### Deembeding S-parameters

I have a deembed S2P(S-parameter) file of the probe and output waveform of the probe. I need to get back the waveform at the probe point by passing the output waveform through the deembed S2P file. ...
3k views

### Frequencies are inherently positive physical quantity.... what does it mean?

While I was going through a digital signal processing course, I came to this problem where it says that "Frequencies are inherently positive physical quantity" - Digital Signal Processing by ...
• 111
47 views

### How to quantise a bipolar analog signal using an ADC with lowest amount of signal noise

I have a linear position sensor that outputs an analogue signal between -4v and +4v corresponding to the position that I want to capture using an ADC and microcontroller. It has a maximum resolution ...
125 views

### Issue with 3rd order Butterworth low pass filter simulation

I wrote up some code in MATLAB that's supposed to simulate the frequency response of a third order passive low pass Butterworth filter with a cutoff at 10kHz. The curve seems to match the results I ...
121 views

### Identifying a line code/binary signal

I'm trying to find out what the following signal/line code is known as. The communication is performed using a single wire, other wires are ground and power (5V). The signal wire is kept high (5V) and ...
• 135
183 views

### How do I plot the DC equivalent of an AC sinusoidal signal in Python?

I want to draw a line that bisects an AC signal as seen in the first picture below. This line should take into consideration any drifts. So essentially, I have an AC voltage signal over time for 3 ...
105 views

### How do I split and isolate a digital signal?

I am working on a circuit that needs to observe when VAC is at zero cross. I have a photostransistor whose anode and cathode are connected to VAC line and neutral. I've connected 3.3VDC to the ...
• 5
37 views

### PE44820 Phase Shifter Confusion in Results

I am using a PE44820 phase shifter for my capstone project. We created our own evaluation board so that we can test it with a raspberry pi3. We are running a simple test first where we are just trying ...
1 vote
88 views

### How to convert an interrupt signal to toggle a continous signal

I am working on a project where a momentary contact micro switch is used to activate the Vdd pin of a 555timer IC - [Datasheet Link]. Thus, I need to toggle the Vdd pin every time a micro switch is ...
• 13
23 views

### Why I am not getting same values for exported simulink variables as stepinfo?

I am using MATLAB 2015a and I am trying to get stepinfo parameters of output that was exported from Simulink to MATLAB workspace but I am not getting same values as if try to get stepinfo for MATLAB ...
• 45
48 views

### Signal analog sensor DHT22

What is the change in humidity percentage for every Celsius degree change on a DHT22 sensor? I would like to know the value before it is converted into a digital signal. For example, in temperature ...
141 views

### How can I split one electrical signal to 3 separate signals?

I have one Hall sender in a gearbox. It creates a square signal to the speedometer with amplitude 0\7.5V. I want to use this signal in two other places, like cruise control control unit and mini ...
51 views

### STM32F407G-DISC1 AUX to Laptop Aux [closed]

I am working with STM32F4 board and signal processing, generating some sin waveforms on CODEC, the problem is that I don't have oscilloscope on me and want to see what waveforms I am generating. I ...
• 433
47 views

### MOSI signal losing bandwidth in SPI communication

I am testing the SPI MOSI signal for signal integrity. The length of the PCB trace is 207 mm. Unfortunately, the signal is curved at the rising edge of the cycle. The frequency is 1Mhz. I think it is ...
1 vote
110 views

### What is the autocorrelation function of this energy signal? [closed]

I would like to know how I would go about finding the autocorrelation function of this energy signal. I tried to integrate the function, but I don't know where to start. The autocorrelation function ...
• 97
149 views

### PWM from the Robodyn AC light dimmer

I am currently conducting a test on a Robodyn AC light dimmer product, and I want to check the PWM trigger output from the controller. Due to equipment limitations, I am only checking the trigger from ...
117 views

### Why is the limit of e to the power of j*infinity equal to infinity?(EDIT: wrong assumption) [closed]

EDIT: I interpreted this step incorrectly. What I said below was never actually implied. A solution to a homework problem for a free online Signals and Systems class I am trying to follow made the ...
1 vote
72 views

### How can I get a consistent answer with operations of piecewise functions?

I am trying to multiply two signals mathematically and graphically. I have inconsistent answers, I'd appreciate anyone that can show me where I went wrong. I have two functions of time based on two ...
• 97
1 vote
82 views

### How can I control a DC circuit via a high voltage AC signal?

I have a low voltage circuit of 9V DC supply voltage and a bunch of LEDs, and another circuit with 50V AC voltage. I want the DC circuit to work only if there is current flowing in the AC circuit. I ...
• 11
67 views

### Building a Hindmarsh-Rose model into a STM32 [closed]

I am wondering if it is possible to simulate Hindmarsh-Rose (HR) model on a embedded systems? I need the output of the embedded system to match the burst/firing rate of a neuron. what protocol could i ...
105 views

### Interfacing a Rpi with absolute encoder using RS-422 (SSI) [closed]

So I am working on a project that requires me reading from an absolute encoder. It uses SSI (RS-422 protocol) and the datasheet is the following: https://www.hohner-elektrotechnik.de/upload/data-sheet-...
1 vote
84 views

### Why multiply by cos(pi/4)

I'm building a circuit to monitor AC current for my house and I have run into a need (in software) to multiply the max ADC value for a given sampling by 0.707 to scale the reading to obtain the ...
72 views

### Changing an output signal

I need a way for the rotational hall sensor that outputs 0-5v to be centered at 2.5v and if it goes below 2.5v the output rises. If it goes above 2.5v the output adjusts down. My goal is to have it ...
87 views

### Why isn’t my overdrive circuit working?

I have attached an image of an overdrive circuit that I have designed for a guitar pedal. I have built the circuit and it isn’t working and I wanted to find out if there were any obvious design flaws/...
115 views

### What is this 2-line communication protocol?

I tried a wide variety of protocol decoders in pulseview including UART, I2C, and SPI, but nothing seems to match. This is captured from communication between a topside controller and the mainboard ...
• 21
236 views

### route on inner or outer layers for SPI clocks signals etc?

What is better for (for example) an SPI clock signal: to be routed on the inner layers (more ground, avoid EMC issue) or on the outer layer? (Avoid changing layers and impedance mismatch and any ...
• 41
34 views

### Signal Function Analysis

I have attempted this problem but am unsure of what the solution should look like. I am confused specifically on the constants a and b, as well as the bounds of the function. I also do not understand ...
122 views

### How to get the transfer function out of a Bode Curve on a datasheet?

I am trying to find the transfer function of AMC1350 out of its datasheet. I dont have any information about which degree of a lowpass filter or what kind it has. DC gain is 2/5. Cutoff frequency is ...
• 850
103 views

### A low noise multiplexer

I am trying to make Faraday's cups array sensor, in which each signal coming from the cups must be amplified because it is too small (microampere or even lower). But since I have too many cups, I need ...
• 73