hsp50210 Intersil Corporation, hsp50210 Datasheet - Page 13

• Manufacturer Part Number: hsp50210
• Description: Digital Costas Loop
• Manufacturer: Intersil Corporation

Loop Gain and potentially, the AGC limits. The maximum AGC
response is the maximum gain adjustment made in any given
clock cycle. This involves applying maximum Loop gain and
setting the AGC limits as wide as possible. A calculation using
AGC Response
where (0.5) is the MSB of the 0.81 scaling in the Cartesian to Polar Coordinate Converter, (0.5) is the MSB of the mantissa of the
Loop Gain, (2
A similar procedure is used to calculate the minimum AGC response rate.
Thus, the expected range for the AGC rate is approximately 0.0004 to 0.0469dB/symbol time.
POSITION
ACCUM
AGC
BIT
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
AGC Response
AGC Response
-7
ERROR
MAX
INPUT
GAIN
8(S)
) is the maximum shift gain, and 24 is the maximum loop filter gain.
7
6
5
4
3
2
1
0
= Input (Cartesian to Polar Converter Gain)(Error Detector Gain)(AGC Loop Gain)(AGC Output Weighting)
MAX
MIN
WEIGHT
ERROR
= 1(0.5)(0.5)(2
= 1(0.5)(0.5)(2
= 1(S)
GAIN
= 0
BIT
= 1
= 2
= 3
= 4
= 5
= 6
= 7
3-13
FILTER GAIN
(MANTISSA)
AGC LOOP
-14
-7
0.
)(24) = 1(2
x
x
x
x
)(24) = 1(2
TABLE 6. AGC BIT WEIGHTING
MULTIPLIER
AGC LOOP
-9
(OUTPUT)
-16
)(24) = 0.04688dB/symbol time
FILTER
GAIN
12(S)
)(24) = 0.000366dB/symbol time
11
10
9
8
7
6
5
4
3
2
1
0
HSP50210
GAIN BITS
FILTER
LOOP
KEPT
12(S)
(rnd)
AGC
11
10
9
8
7
6
5
only exponent terms of the various gains will be sufficient to
yield a rough order of magnitude of the range of the AGC
Loop response. The results are shaded in the last column of
Table 6 and provided in detail in Equations 9A and 9B.
= 0
= 1
= 1
= 2
= 3
= 4
= 5
= 6
Multiplier
Multiplier
SHIFT
= 0
0
1
1
2
3
4
5
6
Shifter
Shifter
SHIFT
= 7
0
1
1
2
3
4
5
6
M
M
M
M
M
M
G
G
G
G
G
G
G
G
G
G
E
E
LIMITS BIT
G
AND AGC
OUTPUT
WEIGHT
AGC
0-7
-10
-11
-12
-13
-14
-15
-16
-17
-18
-19
-20
-21
-1
-2
-3
-4
-5
-6
-8
-9
1
0
RESOLUTION
0.00000572
0.00000286
AGC GAIN
0.0000916
0.0000458
0.0000229
0.0000114
0.000732
0.000366
0.000183
0.09375
0.04688
0.02344
0.01172
0.00586
0.00293
0.00146
0.1875
0.375
(dB)
0.75
1.5
12
6
3
(EQ. 9A)
(EQ. 9B)