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BUILDING BLOCK FUNCTIONS-FOUNDATION OF DESIGN
Table 4-1. 2920 Implementation Of Basic Functions
Function
# Instructions
(Typical)
4 Quadrant Multiply
12
4 Quadrant Divide
14
Filter Quadratic Function
7 -12
Sawtooth Wave Generator
3-7
Triangle Wave Generator
5-9
Limiter
1
Full Wave Rectifier and
2-4
Single Pole Low Pass Filter
Threshold Detector
2-4
Table 4-2. Bandwidth vs. Program Length
Program Length
Sample
Signal
Inst
%
Rate*
3 dB Bandwidth* *
!
192
100
13KHz
4.33 KHz
154
80
16KHz
5.33 KHz
115
60
22KHz
7.33 KHz
77
40
32KHz
10.7 KHz
39
20
65 KHz
21.7 KHz
*
Assumes 10 MHz Clock Rate. Sample Rate
=
1 9
Hz
(#
inst)(400x 10- )
I
**
Assume BW3 dB:::
3
(Sample Rate)
Consider a value of C
=
1.875. This value could be
expressed several ways. For example:
1.875
=
1.0 + 0.5 + 0.25 + 0.125
=
20 + 2- 1 +2-
2
+ 2-
3
or:
1.875
=
2.0 - .125
=
21 - 2-
3
The first expression could be easily derived from the
binary representation of 1.875 (in binary: 1.111).
However, the second expression uses fewer terms, which
will result in the use of fewer 2920 EPROM words.
4-2
#RAM
Comment
Locations
2
9 Bit X 25 Bit
3
25 Bit
~
9 Bit
2
A Complex Pole
or
Complex Zero
2
9 Bit Amp Accuracy
>
16 Bit Freq. Ace
2
Same as Above
1
Ideal Limiter
1
2
Table 4-3. Sample Applications
# Inst's
Application
#RAM
Locations
192
1200 BPS Full Duplex Modem
38
With Xmit & Receive Filters
And Line Equalization
155
Scanning Spectrum Analyzer
23
With Input Frequency Range
From 200 Hz to 3.2 KHz With
100 Hz Resolution, 48dB
Dynamic Range
115
Approximately 22 Poles/Zeros
24
Of Digital Filtering
Using the second form, a FORTRAN-like expression
for
Y
becomes
y
=
y
+
(2
1
*
X) - (2-
3
*
X)
which could be written as two sequential FORTRAN-
like statements:
y= Y+(2
1
>I<
X)
Y
=
Y - (2-3
*
X)
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