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filterbank
filterbank = Filterbank(<PATH TO FILTERBANK FILE>)
This is an example without parameters, see 2.3 for an example with the parameters.
filterbank.header
Header data contains the following:
| Variable | Description |
|---|---|
| source_name | name of filterbank file |
| P | period of pulsar in ms |
| DM | dispersion measure of pulsar |
| machine_id | id of machine used to receive signal data |
| telescope_id | id of telescope used to receive signal data |
| data_type | type of file filterbank, time series
|
| fch1 | center frequency of first filterbank channel (MHz) |
| foff | filterbank channel bandwidth (MHz) |
| nchans | number of filterbank channels |
| nbits | number of bits per time sample 8, 16 or 32
|
| tstart | timestamp of first sample (MJD) |
| nifs | number of seperate intermediate-frequency channels |
freq_range = fch1 + (foff * nchans + fch1)
time_range = tstart + (tsamp/24/60/60)
freq_range is a tuple with a frequency start and a frequency stop
The same applies to time_range
The header data, including the center frequency, can be retrieved by calling the header attribute from the Filterbank object.
The attributes time_range and freq_range can be passed as parameters to select a specific portion of the filterbank file.
To make the Filterbank object read the filterbank file at once, set the read_all parameter to True.
filterbank = Filterbank(<PATH TO FILTERBANK FILE>, freq_range, time_range, read_all)
The select_data method can be used to retrieve data from the Filterbank object.
The user has the option to give a time and/or frequency range to select a subset from the entire dataset.
The time-range can either be an index of a sample or a float that is represents a moment in time (in seconds).
filterbank.select_data(freq_range, time_range)
The select_data method returns an array of all different channels/frequencies and a large matrix with all the received radio signals.
The matrix contains for each time sample an array which has the intensity per channel/frequency.
When reading the filterbank file as a stream, the user should let the read_all-parameter stay False when initializing the filterbank object.
Each time the user calls the next_row method, it will retrieve an array with intensitiy per frequency for a new time sample from the filterbank file.
When the last iteration of the filterbank is reached, the new_row method will return False.
The same goes for the next_n_rows method, where the user is able to define the amount of rows that should be returned.
filterbank.next_row()
filterbank.next_n_rows(n_rows=10)