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Have I got this right? You're saying the highest cut-off I can implement is 0.5*fs = 62Hz, because that's the highest frequency that can appear in my signal due to nyquist?
so for example, lets say that I want to implement a cut-off frequency of 20Hz, then I would set a to:
a = e^(-2*Pi*20)...
Hi, thanks for your reply,
The Nyquist theorem says that the sampling frequency, fs must be greater than or equal to twice the highest frequency contained in the signal, fh, in order to prevent aliasing, fs >= 2*fh, but I don't understand why this should limit the cutoff frequency fc to between...
Hi,
I am taking recorded measurement data sampled at 8ms (125Hz) and using a library Software function for a low pass filter built into the measurement program.
I have looked at the code of the function, and it uses a parameter, a, ("smoothing factor") where 0 < a < 1, and a = 1 means no...
Hi,
I'm using MPLABx and pickit 3 to try and program a simple circuit based on the pic16f1503 microcontroller (Using ICSP, powered by the boards 5V supply).
I made a basic program to try and turn on an led for debugging purposes, to know I can program it, but after I get the program/verify...
Hi,
I'm not saying the half-bridge mode would cause the error, but rather the starting phase of the pwm output when the duty cycle is written, which would exist even for a single PWM output (At least that is what I think would happen, since the pwm clock is at a different frequency to Fosc...
Thanks, it seems like a good solution, but the time precision needs to be 3us - that is the time difference between the PWM function being called, and an actual output change on the PWM pins needs to be accurate to less than 3us (T +/- 1.5us, where T is constant).
My worry with this method is...
Hi, I want to use the ECCP PWM peripheral on a PIC18F in half-bridge mode to produce an ouptu signal of 40kHz, 50% duty cycle, and I want to be able to switch this on and off so that I can produce bursts of a 40kHz carrier, with a fixed duration - i.e. have a function with "burst width" or...
Hi,
I'm trying to interface a PIC18F46k80 (5V) with a radio module, and I've just realised the module uses 3.3V. I have a circuit built already, and software designed, so I want to know if I can just do a straight swap for a PIC18LF46k80, which runs at 3.3V, without having to change the circuit...
HI, I'm using SPI of PIC18F46K80, and I want to write a function to feed it a 6-bit address, and a read/write bit. If I have the address as a UINT8 type, then how can I change the bits of the UINT8 to construct an 8-bit packet (Another UINT8) with the MSB bit set to '0', followed by the 6-bit...
Hi, I want to detect a pulse on the sensor, so I would pass the output of the amp through a filter, an envelope detector, and then to a comparator, to give me a digital pulse when an ultrasonic pulse is received in the passband of the filter.
I have been told that if I use a fully integrated...
Hi, I want to use an instrumentation amplifier as the first stage of an ultrasonic reciever circuit.
I noticed there are two ways instrumentation amplifiers are used:
-With the REF pin tied to ground, and one pin of the sensor tied to ground
-With the sensor connected across the...
Hi,
I'm using a PIC18F46k80 microcontroller, and I want to use the CTMU for time measurements.
I want to drive a 40kHz ultrasonic transceiver via a bridge circuit, with pulses, and trigger the CTMU current source to begin the time measurement, on the rising edge of the pulse (The second...
Hi all,
I've been looking at UWB radio, and I have found that the FCC has allocated a mask of allowable EIRP spectral density for the UWB band, and I was wondering if this restriction still applies if I am operating equipment inside an environment such as a grounded metal cage, where it is...
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