ADSP-214xx SHARC Processor Hardware Reference
12-7
Asynchronous Sample Rate Converter
address. This offset value is useful for applications when small changes in
the sample rate ratio between
SRCx_FS_IP
and
SRCx_FS_OP
are expected.
The maximum decimation rate can be calculated from the RAM word
depth is (512 – 64)
÷
64 taps = 7.
The digital-servo loop is essentially a ramp filter that provides the initial
pointer to the address in RAM and ROM for the start of the FIR convolu-
tion. The RAM pointer is the integer output of the ramp filter while the
ROM pointer is the fractional part. The digital-servo loop must be able to
provide excellent rejection of jitter on the
SRCx_FS_IP
and
SRCx_FS_OP
clocks as well as measure the arrival of the
SRCx_FS_OP
clock within 4.97
ps. The digital-servo loop also divides the fractional part of the ramp out-
put by the ratio of (
SRCx_FS_IP
)/(
SRCx_FS_OP
) for the case when
SRCx_FS_IP
>
SRCx_FS_OP
, to dynamically alter the ROM coefficients.
The digital-servo loop is implemented with a multi-rate filter. To settle
the digital-servo loop filter quickly at startup or at a change in the sample
Figure 12-2. Sample Rate Converter Architecture
FIFO
HIGH
ORDER
INTERPOLATION
ROM A
DIGITAL
SERVO LOOP
FIR FILTER
ROM B
ROM C
ROM D
SAMPLE RATE
RATIO
SAMPLE RATE RATIO
EXTERNAL RATIO
(MATCHED PHASE MODE)
RIGHT DATA IN
LEFT DATA IN
SRCx_FS_IP
SRCx_FS_OP
SRCx_DAT_OP
SRCx_FS_IP
COUNTER
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Содержание SHARC ADSP-214 Series
Страница 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...