AJ Keller
144 linhas
5.2 KiB
JavaScript
144 linhas
5.2 KiB
JavaScript
// const dgram = require('dgram');
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// const gaussian = require('gaussian');
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// const k = require('openBCIContants');
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// let stream;
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// var startStream = () => {
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// const intervalInMS = 1000 / k.OBCISampleRate200;
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// let sampleNumber = 0;
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// let sampleGenerator = randomSample(4, k.OBCISampleRate200, true, `60Hz`);
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//
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// var getSample = sampleNumber => {
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// let arr = getArrayFromSample(sampleGenerator(sampleNumber));
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// // console.log(`${sampleNumber},${arr[0].toString()},${arr[1].toString()},${arr[2].toString()},${arr[3].toString()}`);
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// return `${sampleNumber},${arr[0].toString()},${arr[1].toString()},${arr[2].toString()},${arr[3].toString()}`;
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// };
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//
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// stream = setInterval(() => {
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// let sampArray = getSample(sampleNumber);
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// // Send the packet to all clients
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// this.emit('read', samp);
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// // Increment the sample number
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// sampleNumber++;
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// }, intervalInMS);
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// };
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/**
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* @description Mainly used by the simulator to convert a randomly generated sample into a std OpenBCI V3 Packet
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* @param sample - A sample object
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* @returns {Array}
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*/
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// function getArrayFromSample (sample) {
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// var array = [];
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// for (var i = 0; i < 4; i++) {
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// array.push(Math.floor(interpret24bitAsInt32(floatTo3ByteBuffer(sample.channelData[i]))));
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// }
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// return array;
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// }
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// function floatTo3ByteBuffer (float) {
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// var intBuf = new Buffer(3); // 3 bytes for 24 bits
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// intBuf.fill(0); // Fill the buffer with 0s
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//
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// var temp = float / (k.OBCIGanglionMCP3912Vref / k.OBCIGanglionMCP3912Gain / (Math.pow(2, 23) - 1)); // Convert to counts
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//
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// temp = Math.floor(temp); // Truncate counts number
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//
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// // Move into buffer
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// intBuf[2] = temp & 255;
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// intBuf[1] = (temp & (255 << 8)) >> 8;
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// intBuf[0] = (temp & (255 << 16)) >> 16;
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//
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// return intBuf;
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// }
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//
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// /**
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// * @description Create a configurable function to return samples for a simulator. This implements 1/f filtering injection to create more brain like data.
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// * @param numberOfChannels {Number} - The number of channels in the sample... either 8 or 16
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// * @param sampleRateHz {Number} - The sample rate
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// * @param injectAlpha {Boolean} - True if you want to inject noise
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// * @param lineNoise {String} - A string that can be either:
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// * `60Hz` - 60Hz line noise (Default) (ex. __United States__)
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// * `50Hz` - 50Hz line noise (ex. __Europe__)
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// * `None` - Do not inject line noise.
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// *
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// * @returns {Function}
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// */
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// var randomSample = (numberOfChannels, sampleRateHz, injectAlpha, lineNoise) => {
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// const distribution = gaussian(0, 1);
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// const sineWaveFreqHz10 = 10;
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// const sineWaveFreqHz50 = 50;
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// const sineWaveFreqHz60 = 60;
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// const uVolts = 1000000;
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//
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// var sinePhaseRad = new Array(numberOfChannels + 1); // prevent index error with '+1'
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// sinePhaseRad.fill(0);
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//
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// // Init arrays to hold coefficients for each channel and init to 0
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// // This gives the 1/f filter memory on each iteration
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// var b0 = new Array(numberOfChannels).fill(0);
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// var b1 = new Array(numberOfChannels).fill(0);
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// var b2 = new Array(numberOfChannels).fill(0);
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//
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// /**
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// * @description Use a 1/f filter
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// * @param previousSampleNumber {Number} - The previous sample number
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// */
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// return previousSampleNumber => {
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// let sample = newSample();
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// for (var i = 0; i < numberOfChannels; i++) { // channels are 0 indexed
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// // This produces white noise
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// let whiteNoise = distribution.ppf(Math.random()) * Math.sqrt(sampleRateHz / 2) / uVolts;
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//
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// switch (i) {
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// case 0: // Add 10Hz signal to channel 1... brainy
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// case 1:
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// if (injectAlpha) {
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// sinePhaseRad[i] += 2 * Math.PI * sineWaveFreqHz10 / sampleRateHz;
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// if (sinePhaseRad[i] > 2 * Math.PI) {
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// sinePhaseRad[i] -= 2 * Math.PI;
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// }
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// whiteNoise += (5 * Math.SQRT2 * Math.sin(sinePhaseRad[i])) / uVolts;
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// }
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// break;
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// default:
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// sinePhaseRad[i] += 2 * Math.PI * sineWaveFreqHz60 / sampleRateHz;
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// if (sinePhaseRad[i] > 2 * Math.PI) {
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// sinePhaseRad[i] -= 2 * Math.PI;
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// }
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// whiteNoise += (8 * Math.SQRT2 * Math.sin(sinePhaseRad[i])) / uVolts;
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// break;
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// }
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// /**
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// * See http://www.firstpr.com.au/dsp/pink-noise/ section "Filtering white noise to make it pink"
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// */
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// b0[i] = 0.99765 * b0[i] + whiteNoise * 0.0990460;
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// b1[i] = 0.96300 * b1[i] + whiteNoise * 0.2965164;
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// b2[i] = 0.57000 * b2[i] + whiteNoise * 1.0526913;
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// sample.channelData[i] = b0[i] + b1[i] + b2[i] + whiteNoise * 0.1848;
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// }
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// if (previousSampleNumber == 255) {
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// sample.sampleNumber = 0;
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// } else {
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// sample.sampleNumber = previousSampleNumber + 1;
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// }
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//
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// return sample;
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// };
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// };
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//
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// function newSample (sampleNumber) {
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// if (sampleNumber || sampleNumber === 0) {
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// if (sampleNumber > 255) {
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// sampleNumber = 255;
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// }
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// } else {
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// sampleNumber = 0;
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// }
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// return {
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// sampleNumber: sampleNumber,
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// channelData: []
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// };
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// }
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