SAF7741 查看數據表（PDF） - NXP Semiconductors.

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SAF7741

Car radio Digital Signal Processor (DSP)

NXP Semiconductors. 

NXP Semiconductors

SAF7741HV

Dual IF car radio and audio DSP (N1F)

7.1.2.14 IQC stage

The IQC stage suppresses the image mirror co-channel within the wanted signal and

corrects for gain and phase imperfections in the analog mixer and the subsequent analog

data base. This is done by measuring and correcting possible correlations between the

wanted and the image signals.

The IQC is an adaptive algorithm based on a Normalized Least Mean Square (NLMS).

Normalization is performed off the data path in the Least Mean Square (LMS) adaptation

engine itself, and therefore does not affect the output signals of the PDC. It takes place in

steps of 6.0 dB with an associated averaging filter. Four coefficients are available to allow

the IQC to manage frequency dependencies introduced by the analog IF filters. The

adaptation rate parameter (mu) is controlled automatically at startup to make sure that the

coefficients converge correctly.

An adaptation freeze level can be set to prevent tap drift in weak signal conditions.n

TEF6730 mode the IQC stage is bypassed.

7.1.2.15 PDC output

The PDC has two outputs; one to the software radio and the other to the external pins. For

the output to the software radio a choice can be made between three signals. The first of

these is the wanted signal at 650 kSa/s. The bandwidth for this is shown in .Figure 11

BANDWIDTH AT 16fs

dB

200

400

600

800

1000

1200

KHz

-20

-40

-60

-80

-100

-120

Fig 11. PDC to EPICS output bandwidth at 650 kSa/s

The second choice is the wanted signal at 325 kSa/s. This is shown in Figure 11. The third

choice is the wanted/image signal pair at 325 kSa/s. The signal bandwidth for this is

shown in Figure 12.

SAF7741_5

Objective data sheet

Rev. 05 — 09 May 2008

© NXP B.V. 2008. All rights reserved.

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