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MSP3400G 参数 Datasheet PDF下载

MSP3400G图片预览
型号: MSP3400G
PDF下载: 下载PDF文件 查看货源
内容描述: 多标准音频处理器系列 [Multistandard Sound Processor Family]
分类和应用:
文件页数/大小: 106 页 / 1906 K
品牌: MICRONAS [ MICRONAS ]
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MSP 34x0G  
DATA SHEET  
6.4.4. NICAM Error Rate Register  
6.4.7. Automatic Search Function for FM-Carrier  
Detection in Satellite Mode  
ERROR_RATE  
Error free  
00 57hex  
0000hex  
07FFhex  
The AM demodulation ability of the MSP 3410G and  
MSP 3450G offers the possibility to calculate the “field  
strength” of the momentarily selected FM carrier,  
which can be read out by the controller. In SAT receiv-  
ers, this feature can be used to make automatic FM  
carrier search possible.  
maximum error rate  
Average error rate of the NICAM reception in a time  
interval of 182 ms, which should be close to 0. The ini-  
tial and maximum value of ERROR_RATE is 2047.  
This value is also active if the NICAM bit of  
MODE_REG is not set. Since the value is achieved by  
filtering, a certain transition time (approx. 0.5 sec) is  
unavoidable. Acceptable audio may have error rates  
up to a value of 700 int. Individual evaluation of this  
value by the controller and an appropriate threshold  
may define the fallback mode from NICAM to FM/  
AM-Mono in case of poor NICAM reception.  
For this, the MSP has to be switched to AM-mode  
(MODE_REG[8]), FM-Prescale must be set to  
7Fhex = +127dec, and the FM DC notch (see section  
6.5.7.) must be switched off. The sound-IF frequency  
range must now be “scanned” in the MSP-channel 2  
by means of the programmable quadrature mixer with  
an appropriate incremental frequency (i.e. 10 kHz).  
After each incrementation, a field strength value is  
available at the quasi-peak detector output (quasi-  
peak detector source must be set to FM), which must  
be examined for relative maxima by the controller. This  
results in either continuing search or switching the  
MSP back to FM demodulation mode.  
The bit error rate per second (BER) can be calculated  
by means of the following formula:  
BER = ERROR_RATE * 12.3*106 /s  
During the search process, the FIR2 must be loaded  
with the coefficient set “AUTOSEARCH”, which  
enables small bandwidth, resulting in appropriate field  
strength characteristics. The absolute field strength  
value (can be read out of “quasi-peak detector output  
FM1”) also gives information on whether a main FM  
carrier or a subcarrier was detected; and as a practical  
consequence, the FM bandwidth (FIR1/2) and the  
deemphasis (50 µs or adaptive) can be switched  
accordingly.  
6.4.5. PLL_CAPS Readback Register  
It is possible to read out the actual setting of the  
PLL_CAPS. In standard applications, this register is  
not of interest for the customer.  
PLL_CAPS  
02 1Fhex L  
minimum frequency  
nominal frequency  
1111 1111  
FFhex  
56hex  
Due to the fact that a constant demodulation frequency  
offset of a few kHz leads to a DC level in the demodu-  
lated signal, further fine tuning of the found carrier can  
be achieved by evaluating the “DC Level Readout  
FM1”. Therefore, the FM DC Notch must be switched  
on, and the demodulator part must be switched back to  
FM-demodulation mode.  
0101 0110  
RESET  
maximum frequency  
PLL_CAPS  
0000 0000  
00hex  
02 1Fhex  
H
PLL open  
xxxx xxx0  
xxxx xxx1  
PLL closed  
6.4.6. AGC_GAIN Readback Register  
It is possible to read out the actual setting of  
AGC_GAIN in Automatic Gain Mode. In standard  
applications, this register is not of interest for the cus-  
tomer.  
AGC_GAIN  
02 1Ehex  
max. amplification  
(20 dB)  
0001 0100  
14hex  
00hex  
min. amplification  
(3 dB)  
0000 0000  
98  
May 27, 2003; 6251-476-1DS  
Micronas