PRODUCT SPECIFICATION
TMC2330A
SADR
SADR
X
Y
TMC2330A
COORDINATE
TRANSFORMER
R
θ
θ
R
SOURCE
IMAGE BUFFER
DATA OUT
(2) TMC2302A IMAGE
RESAMPLING
SEQUENCERS
U
TADR
TADR
U
V
(4) TMC2011A
DELAY
REGISTER
V
Σ
TMC2246A
PIXEL INTERPOLATOR
DATA IN
TARGET
IMAGE
BUFFER
TWR
Figure 1. Figure 1. First Quadrant Coordinate Relationships
Figure 2. Block Diagram of Scan Converter Circuit Utilizing TMC2330A and TMC2302A Image Resampling Sequencer
Arithmetic Error for Two’s
Complement Rectangular to Polar
Conversion
A random set of 5000 input vector coordinate pairs (X,Y),
uniformly spread over a circle of radius 32767 was converted
to polar coordinates.
Radius Error Range
Mean Radius Error
Mean Absolute Radius Error
Phase Error Range
Mean Phase Error
Mean Absolute Phase Error
–0.609 to 0.746 LSB
0.019 LSB
0.252 LSB
–1.373 to 1.469 LSB
0.058 LSB
0.428 LSB
The results of the 10,000-vector study were as follows:
Mean Error (X)
Mean Error (Y)
Mean Absolute Error (X)
Mean Absolute Error (Y)
Root Mean Square Error (X)
Root Mean Square Error (Y)
Max Error (X)
Max Error (Y)
+0.0052 LSB
0.0031 LSB
0.662 LSB
0.664 LSB
1.025 LSB
1.020 LSB
+4/ -5 LSB
+5 -4 LSB
Statistical Evaluation of Double
Conversion
In this empirical test, 10,000 random Cartesian vectors were
converted to and from polar format by the TMC2330A. The
resulting Cartesian pairs were then compared against the
original ones. The un-restricted database represents uniform
sampling over a square bounded by -32769<x<32768 and
-32769<y<32768.
Since this is a double conversion (rectangular to polar and
back) which includes a wide variety of “good case” and “bad
case” vectors, the chip should perform even better in many
real systems. Repeating the experiment and restricting the
original data set to an annulus defined by 8196<R<32768
reduced the mean square error to 0.89 LSB and the peak
error to ±4 LSB (x or y). These latter results are more ger-
mane to synthesizer, demodulator, and other applications in
which the amplitude can be restricted to lie between quarter
and full scale. The largest errors tend to occur in the angle
component of small radius cartesian-to-polar conversion.
12
REV. 1.1.8 10/31/00
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
