Questions tagged [quadrature]

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How to read multiple quadrature encoders using an Arduino

I am developing a 4-wheel mobile robot. Each motor has a quadrature encoder with 2000 pulses per revolution (PPR). I have tried to read the encoders' pulses using an interrupt, but the counted values ...
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-1 votes
1 answer
223 views

Quadrature Decoding using FPGA

I am currently working through FPGA4FUN's tutorial on quadrature decoding using an FPGA. I am currently just trying to simulate the decoders behavior by using a testbench that essentially drives the A ...
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2 votes
1 answer
189 views

How to avoid decay in quadrature oscillator?

Let's consider following quadrature oscillator below (source). It should provide two 90° out of phase sine signals with equal amplitude. It consists of two inverting integrators as well as an ...
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3 answers
164 views

IQ modulation and phasors: which first?

Do we use IQ modulation because quadrature signals are a good physical implementation of phasors - or is it the other way around? To elaborate a little:I'm having a hard time getting a clear ...
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0 answers
141 views

Quadrature encoder (unknown) pinout

I have a quadrature photoresistor from a printer. I want to determine the pinout. I can't find a datasheet for it. The case only shows "80058 - 96315" and I don't know the pinout. The two ...
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1 vote
2 answers
149 views

Encoder direction change during index pulse

I have a quadrature encoder with an index pulse, and I would like to keep track of angular position over multiple turns. The microcontroller I am using has counters that count both index pulses (...
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  • 163
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1 answer
432 views

Driving Stepper Motor with Sine Wave

I am attempting to drive a stepper motor where each phase draws 1 A at 3.5 V using a sine wave oscillator that outputs two signals 90 degrees out of phase with one another. At the outputs of this ...
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0 votes
1 answer
133 views

Frequency modulation synthesis with IQ

I am trying to figure out how the I & Q signals for a frequency modulation have to look like. How do I generate a FM modulated signal with an IQ mixer?
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0 answers
109 views

Quadrature Encoder output overshoot

I have a Faulhaber 1717T006SR DC motor with a build-in quadrature encoder. Here is the relevant bit of the datasheet for the encoder. The encoder outputs are 5V. I want to interface this with an ...
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2 answers
344 views

Schmitt Trigger Level Translation from Encoder

This is my first time using an encoder as well as a Schmitt trigger. Typically, I would do debouncing in software, but I want a hardware solution for the sake of learning how to do so. The encoder I ...
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  • 153
2 votes
0 answers
53 views

What is the meaning of "Demodulation in quadrature sense"? [closed]

With regard to stepped frequency radar, what does it mean when we say that the transmitted signal is "demodulated in a quadrature sense"? The property of interest in this kind of radar is the phase ...
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189 views

How to find the RMS value of a sine wave with DC offset and retain the negative sign

I'm trying to build a Quadrature setup where an input signal is mixed with a reference signal that is in-phase and another one out-of-phase by 90deg. The idea is to extract the real and imaginary ...
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1 vote
2 answers
2k views

Read Quadrature encoders over I2C bus

I need to add encoders to the 4 motors attached to a "remote" PCB. The remote PCB in question does not have microcontroller on it, but rather is connected to the microcontroller PCB with an I2C ...
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2 answers
130 views

4 axis quadrature encoders? [closed]

I am currently working on a digital input card which will feature quadrature encoder inputs. To my (basic) knowledge, quad encoders use two pulse trains that are 90 degrees out of phase with each ...
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0 votes
1 answer
876 views

Quadrature Encoder Interface Circuit

This is an interface circuit of Quadrature Encoder (A, A', B, B') with MCU. I cannot make sense of the working of OpAmps in this circuit. Is it some standard circuit for doing signal conditioning or ...
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1 answer
67 views

Output from a system of cascade connection with Wilkinson's divider and Quadrature hybrid

So I have this system, with \$f=3GHz\$ \$b = \frac{λ}{4}\$ \$a = 0<a<b\$ and I want to know the output at ports 2 and 3. I'm wondering how exactly I should approach it, and if my sketch is ...
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3 votes
1 answer
479 views

design a 90 degree hybrid coupler 2-8GHZ

I designed a 90 degree hybrid coupler in hfss, in 5~6 GHZ. S₁₁ & phase difference are okay, but S₂₁ & S₃₁ don't match. What change should I make in the form to improve matching between S₂₁ &...
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2 votes
1 answer
82 views

Quadrature modulation Digital to Analog

I want to use an FPGA to generate quadrature modulated signals for use with an RF transceiver (something like MAX2828 ). I am confused specifically about how the digital to analog modulation should ...
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2 votes
0 answers
164 views

Offset QPSK Frame sync markers

What actual protocols exist out there that employ Offset Quadrature Phase-Shift Keying (OQPSK)? What do they use for the frame synchronization marker (or "preamble" or "sync word" or "flag")? Do ...
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0 votes
1 answer
737 views

Best mixer for quadrature FM demodulator

I need to demodulate an FM signal and I want to use a quadrature demodulator for this. The signal is 16±0.15 MHz, 3.3V output from CMOS oscillator. I know that Gilbert cell mixers are most commonly ...
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2 votes
2 answers
2k views

What is the best oscillator to be used in a capacitive soil moisture sensor?

I am working on this project where I am going to make a soil moisture sensor. The principal that I'm going to use is the change of capacitance of the soil with moisture. What I'm going to do is make a ...
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2 votes
3 answers
349 views

Quadrature encoder has one synced edge and one phase-shifted edge, is this a special encoding scheme?

Special encoder output scheme? I am testing an inexpensive encoder and encountered a strange but consistent output pattern. In other encoders I've used, the A signal consistently has a 90 degree or -...
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1 vote
3 answers
2k views

Easiest way to generate quadrature signal on PCB

I have a chip which needs a quadrature LO. Specifications: Frequency range: 1.7 GHz - 2.5 GHz (wider range appreciated) Both I/Q differential (i.e. 4 wires in total) Each wire 1Vpp DC offset of 500mV ...
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1 vote
1 answer
278 views

13Bit Encoder interface for microcontroller

I am running out of time and seeking a proper solution. What I am willing to achive is getting the position of the encoder / motor shaft. To keep track of the movement. (Currently I am running 10 turn ...
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  • 87
1 vote
1 answer
75 views

Quadrature signal with L297

I'm trying to generate a quadrature signal with a L297 http://www.st.com/content/ccc/resource/technical/document/datasheet/f9/35/6e/3f/48/18/48/51/CD00000063.pdf/files/CD00000063.pdf/jcr:content/...
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  • 311
2 votes
1 answer
257 views

Frequency Dependent IQ imbalance

I would like to know does anyone know how to model the frequency dependent IQ imbalance. The frequency independent model is when gain and phase imbalance are just constant now assume that gain and ...
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-2 votes
1 answer
83 views

Design of microstrip tranmission line

this might sound silly but I am a little confused as to how the quadrature coupler relates to the microstrip transmission line.
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  • 57
1 vote
1 answer
433 views

Microstrip design

I have a task which is to design a circuit using microstrip transmission lines. this circuit should generate two output signals of equal power, one which is in phase with the input sine signal and the ...
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6 votes
2 answers
617 views

What could cause a quadrature encoder to produce this output?

I'm working on a software quadrature decoder and testing with a Lego EV3 medium motor (which has an integrated quadrature encoder). The thing is, while the large motor produces perfectly normal-...
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  • 316
4 votes
6 answers
9k views

Removing digital noise on quadrature encoder signals

I am using a quadrature encoder with 3 lines to track the rotary position of a shaft attached to a BLDC motor(through a planetary gearbox). When I rotate the shaft, the A, B and Z lines always have ...
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0 votes
1 answer
140 views

How does this click wheel work

I am now trying to fix a camera control wheel, like the one in the top right corner of this camera (not the one which I am fixing): This is a cheap part but I cannot find a replacement for my camera ...
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0 votes
1 answer
1k views

Reading 2 Quadrature encoders using a single Arduino Due

I am working on an autonomous robot in my summer vacations. I am currently working on running the motors of my robot in a closed loop. In order to do so, I have to interface two Quadrature encoders of ...
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-1 votes
1 answer
559 views

Quadrature Amplitude Modulation (QAM) 16

How do we represent the most significant and least signuficant bits in QAM 16 as we do in QAM 4 with cos(x), -cos(x), sin(x), and -sin(x). Then, by adding these waves we generate the final wave ...
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0 votes
0 answers
485 views

QAM Modulation Frequency vs Carrier Frequency

In QAM (Quadrature Amplitude Modulation) theory what is the relationship between the modulation frequency and the carrier frequency called? It is often stated in QAM tutorials that the carrier ...
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0 votes
1 answer
359 views

A question related to "quadrature carrier multiplexing"

While studying 'Qaudrature carrier multiplexing', I came across these statements in my text material: "Precisely varying the phase of a high-frequency carrier sine wave in a hardware circuit ...
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  • 153
0 votes
1 answer
346 views

Can't seem to determine quadrature encoder resolution

I'm currently working on an autonomous terrain-mapping rover, and I've run into problems in the seemingly most straight-forward area: processing quadrature encoder data. For any unfamiliar, a ...
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3 votes
3 answers
1k views

Separating the AM and QAM components in PAL signal demodulation

I'm attempting to emulate the modulation and demodulation of a PAL video frame in software, but I'm having trouble understanding how the AM (luma) and QAM (UV) components of the signal are separated ...
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  • 6,637
4 votes
2 answers
3k views

FPGA encoder counter running away randomly

I am programming an Altera FPGA using Quartus II v9.0 to count encoder pulses and output that count to an external LabVIEW program (see diagram below). I was able to debug one issue with my code ...
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  • 199
0 votes
1 answer
1k views

Quadrature counter on FPGA is running away

I am attempting to count pulses from a quadrature encoder in an Altera FPGA. I believe I have my counter set up correctly (circuit diagram below, following this tutorial), but when I turn my encoder ...
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  • 199
0 votes
2 answers
601 views

What component (IC) to use for collecting A and !A signals into a single TTL signal?

I am building a circuit board to listen to quadrature encoder signals from a motor controller and send these signals on to an FPGA that will be used to count the pulses and direction. The signals ...
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  • 199
1 vote
1 answer
1k views

Driving a Turntable with a Two-Phase, Bipolar Stepper

I'm a relative newbie to electronics, and as an educational project I'm building a record turntable. I'm comfortable with the purely mechanical aspects of the project, but I need some help ...
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41 votes
4 answers
46k views

Can somebody explain what IQ (quadrature) means in terms of SDR?

This is a bit of a basic question, but I am having trouble understanding why a signal needs to be broken up into I and Q components to be useful for software-defined radio (SDR). I understand that ...
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