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Questions tagged [quadrature]

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2
votes
1answer
45 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 ...
-1
votes
0answers
68 views

what is the max speed of stm32f103c8tx in encoder mode?

I am using STM32f103 with STM32cubemx and Atollic studio, what is the maximum pulse rate (frequency) input that can be counted with STM32f103 TIM Encoder Quadrature mode? also if I configure two ...
2
votes
0answers
38 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 ...
0
votes
1answer
246 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 ...
1
vote
2answers
373 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 ...
2
votes
2answers
69 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 -...
0
votes
0answers
117 views

Keeping constant bandwidth in tunable quadrature FM demodulator

I need to demodulate an FM signal (4 MHz max deviation) with a strong center frequency drift (550-800 MHz). I've built an AFC circuit to track the drift and now I need to build a tunable quadrature ...
1
vote
3answers
468 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 ...
1
vote
0answers
1k views

Selecting an appropriate pull-up resistor for a rotary encoder

I am working on a university project that requires a quadrature rotary encoder. I have been supplied with a HN3806-AB-600N without a data sheet and the only useful information I can find via Google ...
1
vote
1answer
165 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 ...
1
vote
1answer
56 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/...
3
votes
1answer
189 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 ...
-2
votes
1answer
71 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.
1
vote
1answer
257 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 ...
6
votes
2answers
447 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-...
3
votes
6answers
4k 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 ...
0
votes
1answer
134 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 ...
0
votes
1answer
622 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 ...
-1
votes
1answer
386 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 ...
0
votes
0answers
306 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 ...
0
votes
1answer
328 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 ...
0
votes
1answer
258 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 ...
3
votes
3answers
708 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 ...
4
votes
2answers
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 ...
0
votes
1answer
871 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 ...
0
votes
2answers
434 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 ...
1
vote
1answer
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 ...
29
votes
4answers
40k 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 ...