Move all RTLSDR logic into sub-module

lib/rtlsdr.js

@@ -0,0 +1,96 @@
+'use strict'
+
+const rtlsdr = require('rtl-sdr')
+const Demodulator = require('mode-s-demodulator')
+const debug = require('debug')('airplanejs')
+const store = require('./store')
+
+const DEFAULT_RATE = 2000000
+const DEFAULT_FREQ = 1090000000
+const ASYNC_BUF_NUMBER = 12
+const DATA_LEN = 16 * 16384 // 256k
+
+const noop = function () {}
+const demodulator = new Demodulator()
+
+let dev
+
+exports.start = function (argv) {
+ if (dev) throw new Error('Cannot start rtlsdr more than once')
+
+ // Connect to RTLSDR device
+ dev = setupDevice(argv)
+
+ // Start reading data from RTLSDR device
+ rtlsdr.read_async(dev, onData, noop, ASYNC_BUF_NUMBER, DATA_LEN)
+}
+
+exports.stop = function () {
+ rtlsdr.cancel_async(dev)
+ rtlsdr.close(dev)
+}
+
+function onData (data, len) {
+ demodulator.process(data, len, onMsg)
+}
+
+function onMsg (msg) {
+ store.addMessage(msg)
+}
+
+function setupDevice (argv) {
+ let gain = argv.gain || argv.g
+ const findMaxGain = !('gain' in argv || 'g' in argv)
+ const autoGain = argv['auto-gain'] || false
+ const enableAgc = argv['enable-agc'] || false
+ const devIndex = argv.device || argv.d || 0
+ const freq = argv.frequency || argv.f || DEFAULT_FREQ
+
+ const ppmError = 0
+ const vendor = Buffer.alloc(256)
+ const product = Buffer.alloc(256)
+ const serial = Buffer.alloc(256)
+
+ const deviceCount = rtlsdr.get_device_count()
+ if (!deviceCount) {
+ console.error('No supported RTLSDR devices found.')
+ process.exit(1)
+ }
+
+ debug('Found %d device(s):', deviceCount)
+ for (let j = 0; j < deviceCount; j++) {
+ rtlsdr.get_device_usb_strings(j, vendor, product, serial)
+ debug('%d: %s, %s, SN: %s %s', j, vendor, product, serial, j === devIndex ? '(currently selected)' : '')
+ }
+
+ const dev = rtlsdr.open(devIndex)
+ if (typeof dev === 'number') {
+ console.error('Error opening the RTLSDR device: %s', dev)
+ process.exit(1)
+ }
+
+ // Set gain, frequency, sample rate, and reset the device
+ rtlsdr.set_tuner_gain_mode(dev, autoGain ? 0 : 1)
+ if (!autoGain) {
+ if (findMaxGain) {
+ // Find the maximum gain available
+ const gains = new Int32Array(100)
+ const numgains = rtlsdr.get_tuner_gains(dev, gains)
+ gain = gains[numgains - 1]
+ debug('Max available gain is: %d', gain / 10)
+ }
+ debug('Setting gain to: %d', gain / 10)
+ rtlsdr.set_tuner_gain(dev, gain)
+ } else {
+ debug('Using automatic gain control')
+ }
+
+ rtlsdr.set_freq_correction(dev, ppmError)
+ if (enableAgc) rtlsdr.set_agc_mode(dev, 1)
+ rtlsdr.set_center_freq(dev, freq)
+ rtlsdr.set_sample_rate(dev, DEFAULT_RATE)
+ rtlsdr.reset_buffer(dev)
+ debug('Gain reported by device: %d', rtlsdr.get_tuner_gain(dev) / 10)
+
+ return dev
+}

server.js

@@ -7,16 +7,9 @@ const debug = require('debug')('airplanejs')
 const getPort = require('get-port')
 const opn = require('opn')
 const patterns = require('patterns')()
-const rtlsdr = require('rtl-sdr')
-const Demodulator = require('mode-s-demodulator')
-const store = require('./lib/store')
+const rtlsdr = require('./lib/rtlsdr')
 const routes = require('./lib/routes')
 
-const DEFAULT_RATE = 2000000
-const DEFAULT_FREQ = 1090000000
-const ASYNC_BUF_NUMBER = 12
-const DATA_LEN = 16 * 16384 // 256k
-
 process.on('SIGINT', exit)
 
 const argv = require('minimist')(process.argv.slice(2))
@@ -30,83 +23,12 @@ if (argv.version || argv.v) {
  process.exit()
 }
 
-const noop = function () {}
-const demodulator = new Demodulator()
-
-// Connect to RTLSDR device
-const dev = setupDevice()
-
-// Start reading data from RTLSDR device
-rtlsdr.read_async(dev, onData, noop, ASYNC_BUF_NUMBER, DATA_LEN)
+// Start radio
+rtlsdr.start(argv)
 
 // Start HTTP server
 startServer()
 
-function onData (data, len) {
- demodulator.process(data, len, onMsg)
-}
-
-function onMsg (msg) {
- store.addMessage(msg)
-}
-
-function setupDevice () {
- let gain = argv.gain || argv.g
- const findMaxGain = !('gain' in argv || 'g' in argv)
- const autoGain = argv['auto-gain'] || false
- const enableAgc = argv['enable-agc'] || false
- const devIndex = argv.device || argv.d || 0
- const freq = argv.frequency || argv.f || DEFAULT_FREQ
-
- const ppmError = 0
- const vendor = Buffer.alloc(256)
- const product = Buffer.alloc(256)
- const serial = Buffer.alloc(256)
-
- const deviceCount = rtlsdr.get_device_count()
- if (!deviceCount) {
- console.error('No supported RTLSDR devices found.')
- process.exit(1)
- }
-
- debug('Found %d device(s):', deviceCount)
- for (let j = 0; j < deviceCount; j++) {
- rtlsdr.get_device_usb_strings(j, vendor, product, serial)
- debug('%d: %s, %s, SN: %s %s', j, vendor, product, serial, j === devIndex ? '(currently selected)' : '')
- }
-
- const dev = rtlsdr.open(devIndex)
- if (typeof dev === 'number') {
- console.error('Error opening the RTLSDR device: %s', dev)
- process.exit(1)
- }
-
- // Set gain, frequency, sample rate, and reset the device
- rtlsdr.set_tuner_gain_mode(dev, autoGain ? 0 : 1)
- if (!autoGain) {
- if (findMaxGain) {
- // Find the maximum gain available
- const gains = new Int32Array(100)
- const numgains = rtlsdr.get_tuner_gains(dev, gains)
- gain = gains[numgains - 1]
- debug('Max available gain is: %d', gain / 10)
- }
- debug('Setting gain to: %d', gain / 10)
- rtlsdr.set_tuner_gain(dev, gain)
- } else {
- debug('Using automatic gain control')
- }
-
- rtlsdr.set_freq_correction(dev, ppmError)
- if (enableAgc) rtlsdr.set_agc_mode(dev, 1)
- rtlsdr.set_center_freq(dev, freq)
- rtlsdr.set_sample_rate(dev, DEFAULT_RATE)
- rtlsdr.reset_buffer(dev)
- debug('Gain reported by device: %d', rtlsdr.get_tuner_gain(dev) / 10)
-
- return dev
-}
-
 function startServer () {
  patterns.add('GET /', routes.index)
  patterns.add('GET /assets/{file}', routes.assets)
@@ -168,7 +90,6 @@ function help () {
 
 function exit () {
  console.log('Closing down RTL-SDR device...')
- rtlsdr.cancel_async(dev)
- rtlsdr.close(dev)
+ rtlsdr.stop()
  process.exit()
 }