Module `bhreader`¶

This module contains functions to load and decode files from Becker & Hickl hardware.

The high-level function in this module are:

load_spc() which loads and decoded the photon data from SPC files.
load_set() which returns a dictionary of metadata from SET files.

Becker & Hickl SPC Format¶

The structure of the SPC format is here described.

SPC-600/630¶

SPC-600/630 files have a record of 48-bit (6 bytes) in little endian (<) format. The first 6 bytes of the file are an header containing the timestamps_unit (in 0.1ns units) in the two central bytes (i.e. bytes 2 and 3). In the following drawing each char represents 2 bits:

bit: 64        48                          0
     0000 0000 XXXX XXXX XXXX XXXX XXXX XXXX
               '-------' '--' '--'   '-----'
field names:       a      c    b        d

     0000 0000 XXXX XXXX XXXX XXXX XXXX XXXX
               '-------' '--' '--' '-------'
numpy dtype:       a      c    b    field0

macrotime = [ b  ] [     a     ]  (24 bit)
detector  = [ c  ]                (8 bit)
nanotime  = [  d  ]               (12 bit)

overflow bit: 13, bit_mask = 2^(13-1) = 4096

SPC-134/144/154/830¶

SPC-134/144/154/830 files have a record of 32-bits (4 bytes) in little endian (<) format. The first 4 bytes of the file are an header containing the timestamps_unit (in 0.1ns units) in first two bytes. In the following drawing each char represents 2 bits:

bit:                     32                0
                         XXXX XXXX XXXX XXXX
                         '''-----' '''-----'
field names:             a    b    c    d

                         XXXX XXXX XXXX XXXX
                         '-------' '-------'
numpy dtype:              field1    field0

macrotime = [ d ]       (12 bit)
detector  = [ c ]       (4 bit)
nanotime  = [ b ]       (12 bit)
aux       = [ a ]       (4 bit)

aux = [invalid, overflow, gap, mark]

If overflow == 1 and invalid == 1 --> number of overflows = [ b ][ c ][ d ]

List of functions¶

High-level functions to load and decode Becker & Hickl SPC/SET pair of files:

phconvert.bhreader.load_spc(fname, spc_model='SPC-630')¶

Load data from Becker & Hickl SPC files.

Parameters:	spc_model (string) – name of the board model. Valid values are ‘SPC-630’, ‘SPC-134’, ‘SPC-144’, ‘SPC-154’ and ‘SPC-830’.
Returns:	3 numpy arrays (timestamps, detector, nanotime) and a float (timestamps_unit).

phconvert.bhreader.load_set(fname_set)¶: Return a dict with data from the Becker & Hickl .SET file.

Low-level functions¶

These functions are the building blocks for decoding Becker & Hickl files:

phconvert.bhreader.bh_set_identification(fname_set)¶

Return a dict containing the IDENTIFICATION section of .SET files.

The both keys and values are native strings (binary strings on py2 and unicode strings on py3).

phconvert.bhreader.bh_set_sys_params(fname_set)¶

Return a dict containing the SYS_PARAMS section of .SET files.

The keys are native strings (traditional strings on py2 and unicode strings on py3) while values are numerical type or byte strings.

phconvert.bhreader.bh_decode(s)¶: Replace code strings from .SET files with human readable label strings.

phconvert.bhreader.bh_print_sys_params(sys_params)¶: Print a summary of the Becker & Hickl system parameters (.SET file).