Use of radio astronomy
techniques in the analysis of
acoustic phased array signals
from the body
Stephen Hughes, Madeleine McIntyre, Sanjay Mishra, Queensland University of
Technology
Steven Tingay, Curtin University of Technology, Perth, WA
Graham Tronc, Wesley Hospital, Brisbane
Suresh R. Devasahayam, Christian Medical Centre, Vellore, India
NRAO / AUI / NSF
Research question
Is it possible to use the correlation
techniques used in radio
astronomy to extract diagnostic
information from sounds
generated naturally in the body–
e.g. leaking blood vessels, fetal
heart rate, cancer cell death
during chemotherapy, etc?
Pinard stethoscope being used to
listen to fetal heart beats in India
Signals received at the
focus of each dish are
amplified using cryogenic
electronics
At the Paul Wild Observatory, Narribri, NSW, radio
signals are collected using a phased array of six 22m radio dishes
.. and correlated by a hardware correlator.
Digitised signals are sent to the control building via
fibre optic cable…
ct
Wavefront from space
1
2
Radio dishes
Wavefronts coming in at a slightly
different angle to each other
Radio dishes
Radio image of a spiral galaxy
+9V
Microphones
10 k
+9V
24.1 nF
–
Audio Amplifiers
to ADC
100 k
Analogue to Digital
Convertor (ADC) (NI
9215)
Electret
microphone
+
150 k
-9V
10 k
Base Unit (NI
cDAQ 9172)
Computer
Four channels, simultaneous sampling,
100 kHz, 16-bit
Time domain signal of abdominal
recording from a pregnant mother
Some structure present which
may be due to the maternal and
fetal heart beat
Autocorrelation function
Software correlator pipeline
Ch1
Ch2
FFT
FFT
Filter
Filter
×
IFFT
CCF
Complex
conjugate
Software based on the DiFX correlator developed by Tingay et al. (PERL -> Matlab -> Scilab)
Heart sound – no gel
Heart sound –gel
Plastic holder for electret
microphone with gel interface
Spectrum of heart sound – gel
Filtered heart sound – gel
Acoustic phased array
Tumor
Research plan
(cancer)
•Build an array acoustic sensors (e.g.
microphones/accelerometers/piezoelectric elements)
•Develop software to calculate the CCF of multiple sensor
baselines –can an acoustic image be generated?
•See if it is possible to detect cancer cells dying as a result
of chemotherapy drugs
•Develop a system for the early detection of the efficacy
or otherwise of chemotherapeutic agents
•Investigate ways of being able to transmit acoustic data
over wireless networks to a central correlator facility
THE END
SKA