README

(I) Overview

This directory contains the source code for an experiment John Doty and Matthew Wampler-Doty have been conducting which investigates whether cosmic gamma ray bursts are detectable by monitoring highly regular low bandwith radio signals (10kHZ to 100kHZ).  The operating hypothesis is that cosmic gamma ray bursts cause ionization in the upper atmosphere, that in turn changes the phase of radio signals in the specified spectrum.

The WWVB atomic clock signal out of Fort Collins, CO pulses at 60kHZ exactly once every second.  Every 10 minutes on the hour the phase of the signal is shifted by 45 degrees, and is then adjusted back after 5 minutes.  We monitor this system using a custom designed high-precision ovenized crystal oscillator, which is used as an external trigger for the PCI-DAS1602 data acquisition card (by the company formerly known as Measurement Computing).

The data acquisition software is written in C using COMEDI.  The data acquisition code assumes a RTLinux kernel, since it demands real-time priority.  

After data is acquired, it is streamed through a python script.  There the phase of the signal each second is calculated, as well as the amplitude.  The WWVB uses an amplitude-shift keying system, so from the amplitude of each second a binary value (0 or 1) may be recovered. The time offset, phase, amplitude, and the calculated binary values (for the phase) are dumped to a tab seperated value file (tsv).

The WWVB encodes the time in these binary values; this code is described here:

http://en.wikipedia.org/wiki/WWVB

The time is then calculated from this signal.  File names are time stamped using this measured time.  The time is also used to control for the phase shift that occurs every five minutes on the hour.

The data gathered is intended to be used in comparison to other gamma ray burst events gathered by other means.  To this end, we have written software for processing gamma ray burst data from the Fermi satellite.  For each gamma ray burst, PyEphem is used to determine whether the event occured above or below the horizon of the location of the experiment (in this case, Pine, CO).  An XEphem database of suitable events is compiled, which are used as reference points for data analysis of the experimental data.


(II) Files & Directories

gEDA/		Schematics & Layouts for circuit components

fermi/		Python, Shell and AWK scripts for processing
		Fermi events, grabbed from:
		http://gcn.gsfc.nasa.gov/fermi_grbs.html

Data/		This directory is for collected data.  
		Repository version should be empty

wwvbaq.c	COMEDI driver for the PCI-DAS1602/16
		Outputs a stream of floats
		Realtime priority: 70

wwvbred.py	A python script that processes raw data from the
		data acquisition card.
		Outputs a TSV file, with fields for
		(1) time of data-acquisition (as offset)
		(2) phase
		(3) amplitude
		(4) bit value
		File names are determined by time read from the bit-stream

wwvbaq.sh	Runs the data acquisition process

wwvbaq_rename.py Renames data files based on time codes within

mvloop.sh	Runs wwvbaq_rename.py repeatedly