DirectDemod: Modules documentation¶

Signal object¶

class directdemod.comm.commSignal(sampRate, sig=array([], dtype=float64), chunker=None)[source]¶

This is an object used to store a signal and its properties

__init__(sampRate, sig=array([], dtype=float64), chunker=None)[source]¶

Initialize the object

Parameters

sampRate (int) – sampling rate in Hz, will be forced to be an integer
sig (numpy array, optional) – must be one dimentional, will be forced to be a numpy array
chunker (chunker, optional) – Chunking object, if this signal is going to be processed in chunks

bwLim(tsampRate, strict=False, uniq='abcd')[source]¶

Limit the bandwidth by downsampling

Parameters

tsampRate (int) – target sample rate
strict (bool, optional) – if true, the target sample rate will be matched exactly
uniq (str, optional) – in case chunked signal, uniq is to differentiate different bwLim funcs

Returns

Updated signal (self)

Return type

commSignal

extend(sig)[source]¶

Adds another signal to this one at the tail end

Parameters: sig (commSignal) – Signal to be added
Returns: Updated signal (self)
Return type: commSignal

filter(filt)[source]¶

Apply a filter to the signal

Parameters: filt (filter) – filter object
Returns: Updated signal (self)
Return type: commSignal

funcApply(func)[source]¶

Applies a function to the signal

Parameters: func (function) – function to be applied
Returns: Updated signal (self)
Return type: commSignal

property length¶

get length of signal

Type: int

offsetFreq(freqOffset)[source]¶

Offset signal by a frequency by multiplying a complex envelope

Parameters: freqOffset (float) – offset frequency in Hz
Returns: Signal offset by given frequency (self)
Return type: commSignal

property sampRate¶

get sampling rate of signal

Type: int

property signal¶

get signal

Type: numpy array

updateSignal(sig)[source]¶

Updates the signal

Parameters: sig (numpy array) – New signal array
Returns: Updated signal (self)
Return type: commSignal

Specific applications¶

class directdemod.decode_noaa.decode_noaa(sigsrc, offset, bw=None)[source]¶

Object to decode NOAA APT

__init__(sigsrc, offset, bw=None)[source]¶

Initialize the object

Parameters

sigsrc (commSignal) – IQ data source
offset (float) – Frequency offset of source in Hz
bw (int, optional) – Bandwidth

property channelID¶

get channel ID’s

Returns: [channelIDA, channelIDB]
Return type: list

getAccurateSync(useNormCorrelate=True)[source]¶

Get the sync locations: at highest sampling rate

Parameters: useNormCorrelate (bool, optional) – Whether to use normalized correlation or not
Returns: A list of locations of sync in sample number (start of sync)
Return type: list

property getAudio¶

Get the audio from data

Returns: An audio signal
Return type: commSignal

property getColor¶

Get false color image (EXPERIMENTAL)

Returns: A matrix list of pixel
Return type: numpy array

getCrudeSync()[source]¶

Get the sync locations: at constants.NOAA_CRUDESYNCSAMPRATE sampling rate

Returns: A list of locations of sync in sample number (start of sync)
Return type: list

property getImage¶

Get the image from data

Returns: A matrix of pixel values
Return type: numpy array

property getImageA¶

Get Image A from the extracted image

Returns: A matrix list of pixel
Return type: numpy array

property getImageB¶

Get Image B from the extracted image

Returns: A matrix list of pixel
Return type: numpy array

getMapImage(cTime, destFileRot, destFileNoRot, satellite, tleFile=None)[source]¶

Get the map overlay of the image

Parameters

cTime (datetime) – Time of start of capture in UTC
tleFile (str, optional) – TLE file location, pulls latest from internet if not given
destFile (str) – location where to store the image
satellite (str) – Satellite name, ex: NOAA 19 etc.

property useful¶

10 consecutive syncs apart by 0.5s+-error

Returns: 0 if not found, 1 if found
Return type: int
Type: See if some data was found or not

class directdemod.decode_afsk1200.decode_afsk1200(sigsrc, offset, bw)[source]¶

Object to decode AFSK1200

__init__(sigsrc, offset, bw)[source]¶

Initialize the object

Parameters

sigsrc (commSignal) – IQ data source
offset (float) – Frequency offset of source in Hz
bw (int, optional) – Bandwidth

decode_nrzi()[source]¶

Decode NRZI

Parameters: nrzi (list) – the NRZI bits
Returns: decoded NRZI bits
Return type: list

find_bit_stuffing()[source]¶

To find bit stuffing

Parameters: code_bit (list) – the bits
Returns: bit stuffing status
Return type: list

property getMsg¶

Get the message from data

Returns: string: A string of message data

reduce_stuffed_bit(stuffed_bit)[source]¶

To remove stuffed bits

Parameters

code_bit (list) – the bits
stuffed_bit (list) – the result from find_bit_stuffing()

Returns

bits free from stuffing

Return type

list

property useful¶

See if atleast one message was found or not

Returns: 0 if not found, 1 if found
Return type: int

class directdemod.decode_funcube.decode_funcube(sigsrc, offset, bw, center_frequency, signal_freq, corrfreq=False)[source]¶

Object to decode Funcube

__init__(sigsrc, offset, bw, center_frequency, signal_freq, corrfreq=False)[source]¶

Initialize the object

Parameters

sigsrc (commSignal) – IQ data source
offset (float) – Frequency offset of source in Hz
bw (int, optional) – Bandwidth

property getSyncs¶

Get syncs of Funcube

Returns: list of detected syncs
Return type: list

property useful¶

See if signal was found

Returns: 0 if not found, 1 if found
Return type: int

class directdemod.decode_meteorm2.decode_meteorm2(sigsrc, offset, bw)[source]¶

Object to decode Meteor m2

__init__(sigsrc, offset, bw)[source]¶

Initialize the object

Parameters

sigsrc (commSignal) – IQ data source
offset (float) – Frequency offset of source in Hz
bw (int, optional) – Bandwidth

property getSyncs¶

Get syncs of Meteor M2

Returns: list of detected syncs
Return type: list

property useful¶

See if signal was found

Returns: 0 if not found, 1 if found
Return type: int

Filters¶

class directdemod.filters.filter(b, a, storeState=True, zeroPhase=False, initOut=None)[source]¶

This is a parent object of all filters, it implements all the necessary properties. Refer to experiment 3 for details.

__init__(b, a, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

b (list) – list of ‘b’ constants of filter
a (list) – list of ‘a’ constants of filter
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

applyOn(x)[source]¶

Apply the filter to a given array of signal

Parameters: x (numpy array) – The signal array on which the filter needs to be applied
Returns: Filtered signal array
Return type: numpy array

property getA¶

Get ‘a’ of the filter

Type: list

property getB¶

Get ‘b’ of the filter

Type: list

class directdemod.filters.rollingAverage(n=3, storeState=True, zeroPhase=False, initOut=None)[source]¶

A simple rolling average filter

__init__(n=3, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

n (int, optional) – size of the rolling window
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

class directdemod.filters.blackmanHarris(n, storeState=True, zeroPhase=False, initOut=None)[source]¶

Blackman Harris filter

__init__(n, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

n (int) – size of the window
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

class directdemod.filters.hamming(n, storeState=True, zeroPhase=False, initOut=None)[source]¶

Hamming filter

__init__(n, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

n (int) – size of the window
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

class directdemod.filters.gaussian(n, sigma, storeState=True, zeroPhase=False, initOut=None)[source]¶

Gaussian filter

__init__(n, sigma, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

n (int) – size of the window
sigma (float) – The standard deviation
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

class directdemod.filters.butter(Fs, cutoffA, cutoffB=None, n=6, typeFlt=0, storeState=True, zeroPhase=False, initOut=None)[source]¶

Butterworth filter

__init__(Fs, cutoffA, cutoffB=None, n=6, typeFlt=0, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

Fs (int) – Sampling frequency of signal
cutoffA (float) – desired cutoff A of filter in Hz
cutoffB (float, optional) – desired cutoff B of filter in Hz
n (int, optional) – Order of filter
type (constant, optional) – constants.FLT_LP to constants.FLT_BS, see constants module
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

class directdemod.filters.remez(Fs, bands, gains, ntaps=128, storeState=True, zeroPhase=False, initOut=None)[source]¶

Remez band filter

__init__(Fs, bands, gains, ntaps=128, storeState=True, zeroPhase=False, initOut=None)[source]¶

Initialize the object

Parameters

Fs (int) – sampling frequency in Hz
bands (list) – non-overlapping list of bands (in Hz) in increasing order. e.g [[0, 100], [400, 500], [600, 700]]
gains (float) – Corresponding gains of the bands e.g. [0, 1, 0.5]
ntaps (int, optional) – Number of taps of filter (number of terms in filter)
storeState (bool, optional) – Whether the filter state must be stored. Useful when filtering a chunked signal to avoid border effects.
zeroPhase (bool, optional) – Whether the filter has to provide zero phase error to the input i.e. no delay in the output (Note: Enabling this will disable ‘storeState’ and ‘initOut’)
initOut (list, optional) – Initial condition of the filter

class directdemod.filters.blackmanHarrisConv(n=151)[source]¶

Blackman Harris filter (by convolving, Not recommended for large signals)

__init__(n=151)[source]¶

Initialize the object

Parameters: n (int, optional) – size of the window

applyOn(sig)[source]¶

Apply the filter to a given array of signal

Parameters: x (numpy array) – The signal array on which the filter needs to be applied
Returns: Filtered signal array
Return type: numpy array

Demodulators¶

class directdemod.demod_fm.demod_fm(storeState=True)[source]¶

Object for FM demodulation

__init__(storeState=True)[source]¶

Initialize the object

Parameters: storeState (bool) – Store state? Helps if signal is chunked

demod(sig)[source]¶

FM demod a given complex IQ array

Parameters: sig (numpy array) – numpy array with IQ in complex form
Returns: FM demodulated array
Return type: numpy array

class directdemod.demod_am.demod_am[source]¶

AM demodulation by hilbert’s transform

demod(sig)[source]¶

AM demodulation by hilbert’s transform

Parameters: sig (numpy array) – Signal array to be demodulated
Returns: Demodulated signal
Return type: numpy array

class directdemod.demod_fm.demod_fmAD(storeState=True)[source]¶

Object for FM demodulation (Alternative method using angle differentiation)

__init__(storeState=True)[source]¶

Initialize the object

Parameters: storeState (bool) – Store state? Helps if signal is chunked

demod(sig)[source]¶

FM demod a given complex IQ array

Parameters: sig (numpy array) – numpy array with IQ in complex form
Returns: FM demodulated array
Return type: numpy array

class directdemod.demod_am.demod_amFLT(Fs, cutoff)[source]¶

AM demodulation by low pass filter

__init__(Fs, cutoff)[source]¶

Initialize the object

Parameters: cutoff (int) – lowpass cutoff frequency in Hz

demod(sig)[source]¶

AM demodulation by low pass filter

Parameters: sig (numpy array) – Signal array to be demodulated
Returns: Demodulated signal
Return type: numpy array

Sources¶

class directdemod.source.IQwav(filename, givenSampFreq=None)[source]¶

An IQ.wav file source, typically an output recorded from SDRSHARP or other similar software

__init__(filename, givenSampFreq=None)[source]¶

Initialize the object

Parameters: filename (str) – filename of the IQ.wav file

property length¶

get source length

Type: int

limitData(initOffset=None, finalLimit=None)[source]¶

Limit source data

Parameters

initOffset (int, optional) – starting index
finalLimit (int, optional) – ending index

read(fromIndex, toIndex=None)[source]¶

Read source data

Parameters

fromIndex (int) – starting index
toIndex (int, optional) – ending index. If not provided, the element at location given by fromIndex is returned

Returns

Complex IQ numbers in an array

Return type

numpy array

property sampFreq¶

get sampling freq of source

Type: int

property sourceType¶

get source type

Type: int

Sinks¶

class directdemod.sink.wavFile(filename, sig)[source]¶

This object is used to write wav files

__init__(filename, sig)[source]¶

Initialize the object

Parameters

filename (str) – filename of the wav file
sig (commSignal) – signal to be written

property write¶

writes the signal to file

Type: sig (wavFile)

class directdemod.sink.image(filename, mat)[source]¶

This object is used to display and write images

__init__(filename, mat)[source]¶

Initialize the object

Parameters

filename (str) – filename of the image file
mat (list) – a matrix of pixel values

property show¶

shows the image

Type: sig (image)

property write¶

writes the image to file

Type: sig (image)

Chunking helper¶

class directdemod.chunker.chunker(sigsrc, chunkSize=20000000)[source]¶

This object is just to help in chunking process

__init__(sigsrc, chunkSize=20000000)[source]¶

Initialize the object

Parameters

sampRate (commSignal) – commSignal object to be chunked
chunkSize (int, optional) – chunk size

get(name, init=None)[source]¶

get a variable value for to be used during chunking

Parameters

name (str) – name of the variable
init (anything) – initialize variable to this, if undefined previously

Returns

value of variable

Return type

anything

property getChunks¶

get the created chunks

Type: list

set(name, value)[source]¶

set a variable for to be used during chunking

Parameters

name (str) – name of the variable
value (anything, optional) – value of variable

Logging¶

class directdemod.log.log(file=None, console=False)[source]¶

Object for logging

__init__(file=None, console=False)[source]¶

Initialize the object

Parameters

file (str, optional) – Filename, if log is to be stored into a file
console (bool, optional) – Enables console logging