Research Progress Seminar
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Transcript of Research Progress Seminar
June 7, 2010 1RPS
Hardware and Software Optimization of BABSMOM System
FIR Filter
s1150072 Yumiko Kimezawa
Research Progress Seminar
Outline
• Digital filter• FIR filter• Why is an FIR filter used ?• Structure of an FIR filter• Data flow diagram• Future work
June 7, 2010 RPS 2
Raw ECG/EKGData ROM
VirtualExternalMemory
LEDController
Graphic LCD Controller
SlaveCPU
Slave CPU Memory
Timer Master CPUMemory
MasterCPUTimerShared
MemoryFIR Filter
GraphicLCDLED JTAG
UART
PPD Module Master Module
ADC 1
ADC 12
FIR 1
FIR 12
Buffer
ECGSignal
Analysis
ExternalMemory
1:Signal reading 2:Filtering 3:Analysis
P = # mV Q = # mVR = # mV S = # mV T = # mV U = # mV Interval = # ms
4:Display
June 7, 2010 3RPS
Digital filter
June 7, 2010 RPS 4
•Digital filter Mathematical processing to digital signalNoise rejectionWaveform extraction
•FIR filter- Finite Impulse Response filter
•IIR filter- Infinite Impulse Response filter
There are two main types of a digital filter are
This ECG/EKG system uses an FIR filter.
FIR filter
June 7, 2010 RPS 5
FIR filter•One of the ways to configure a digital filter
•A liner phase
an oscillation does not happen
•Inherent stability
a distortion of waveform does not happen
•Impulse response is finite
Why is an FIR filter used ?
June 7, 2010 RPS 6
The data from analog/digital converter is finite and discrete digital signal.
This ECG/EKG system use FIR filter.
Structure of an FIR filter
June 7, 2010 RPS 7
An FIR filter is shown by the following difference equation.
NnNnn xaxaxany 110][
N
iinixa
0
nx][ny),,1,0( Niai
N
: Input signals
: Output signals
: Filter order
: Filter coefficient
It shows the way to process signals.
Data flow diagram
June 7, 2010 RPS 8
The FIR filter is composed of three parts.
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Figure: The basic block diagram for an FIR filter of N order.
Data flow diagram
June 7, 2010 RPS 9
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Delay element- temporal delay- delay signal for one clock for
sampling
Data flow diagram
June 7, 2010 RPS 10
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Data flow diagram
June 7, 2010 RPS 11
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Multiplier- multiply filter coefficient by an input
signal
Data flow diagram
June 7, 2010 RPS 12
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Data flow diagram
June 7, 2010 RPS 13
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Adder-Add output result from all
multiplier
Difference equation
June 7, 2010 RPS 14
An FIR filter is shown by the following difference equation.
NnNnn xaxaxany 110][
N
iinixa
0
nx][ny),,1,0( Niai
N
: Input signals
: Output signals
: Filter order
: Filter coefficient
1Z 1Z 1Z
nx 1nx 2nx Nnx
0a 1a 2a Na
][ny
Future work
• Understand current ECG Algorithm- Pam Tompskins
• Understand new algorithm developed last year- Period-Peak Detection (PPD) Algorithm
June 7, 2010 RPS 15