Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Real-time Spectrum Analyzer on a PIC18F4550

We usually see spectrum analyzers as decorations to audio equipment – bouncing sets of bars that go up and down depending on what frequency the played tone is. I remembered building a similar project a few years back – its called a Led VU-Meter, though its nothing compared to the complexity of the math behind this project. This real time spectrum analyzer takes in audio signals, amplifies and level shifts it to fit the 0-5V range of the PIC18F4550’s 10 bit analog to digital converter – this is all done through an LM386 operational amplifier. Now the tricky part in this project is called coherency – this is the scheme where it should follow fs/fi = m/n, fs is the sampling frequency of the PIC18F4550’s ADC, Fi is the frequency of the sound being sampled and n is the number of samples. This is a requirement for FFT (which is entirely implemented in C!) or fast fourier transform. Each of the bars/columns of the 128×64 dot-matrix LCD on the spectrum analyzer would be a frequency bin in FFT. Continue reading

TI Calculator Upgrade: 2.4GHz Spectrum Analyzer

A calculator is a complex computing machine evaluating complex mathematical computations, plotting graphs and sometime solves simultaneous linear equations. But some people just can’t get enough of their graphing calculator that they added a spectrum analyzer function not just any other function but a 2.4 GHz spectrum analyzer using a radio transceiver module. The entire 2.4 GHz band is scanned by sweeping from 2.4 to 2.495 GHz checking for signal strengths for each 1 MHz channel that it passes. Any device using the 2.4GHz band will be detected including wireless phones, wireless mouse, wireless networks, microwaves cordless phones and the rest of the gang. A PCA8574 8-bit I/O expander chip was used as the basis for the design; it’s an I2C expander which is capable of controlling 8 bidirectional I/O lines. It gave the Texas Instruments calculator the capability to communicate with TTL devices in this case the CYWM6935 SPI transceiver module. Continue reading

Scopey II – The Great Combination of dsPIC Oscilloscope and Spectrum Analyzer

Do you have a dsPIC oscilloscope and Spectrum analyzer in your lab, but you still think that you didn’t fully used it for a great purpose? Well, then it’s time to use some of your creativity and effort to combine these two stuffs together and transform it into a magnificent Scopey II! Before it, do you know the main function of the Spectrum analyzer? Technically, it is a device used to examine the spectral composition of some electrical, acoustic or optical waveform. Sometimes, it can be also measured the power spectrum as well! Basically, the spectrum analyzer can be divided into two main types and there is analog and digital spectrum analyzer. This is how the Scopey II works… Everything is comes in through the BNC jack on the front and the signal is than attenuated or amplified by the attenuator and amplifier. The gain of the input stage is fully controlled by the PIC and the input stage level will shift the input so it can centers around 2.5v to enable reading negative voltages. Furthermore, the ADC is also… Continue reading