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參數(shù)資料
| 型號： | TDA7405 |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 音頻控制 |
| 英文描述： | 2 CHANNEL(S), TONE CONTROL CIRCUIT, PQFP44 |
| 封裝： | 10 X 10 MM, 1.40 MM HEIGHT, TQFP-44 |
| 文件頁數(shù)： | 28/57頁 |
| 文件大?。?/td> | 750K |
| 代理商： | TDA7405 |
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Figure 34. Highcut characteristics
11
FUNCTIONAL DESCRIPTION OF THE NOISEBLANKER
In the automotive environment the MPX-signal as well as the AM-signal is disturbed by spikes produced by the
ignition and other radiating sources like the wiper-motor. The aim of the noiseblanker part is to cancel the audi-
ble influence of the spikes. Therefore the output of the stereodecoder is held at the actual voltage for a time
between 22 and 38s in FM (370 and 645s in AM-mode). The blockdiagram of the noiseblanker is given in
Figure 34.
Figure 35. Block diagram of the noiseblanker
In a first stage the spikes must be detected but to avoid a wrong triggering on high frequency (white) noise a
complex trigger control is implemented. Behind the triggerstage a pulse former generates the "blanking"-pulse.
11.1 Trigger Path FM
The incoming MPX signal is highpass-filtered, amplified and rectified. This second order highpass-filter has a
corner-frequency of 140kHz. The rectified signal, RECT, is integrated (lowpass filtered) to generate a signal
called PEAK. The DC-charge/discharge behaviour can be adjusted as well as the transient behaviour(MP-dis-
charge control). Also noise with a frequency 140kHz increases the PEAK voltage. The PEAK voltage is fed to
a threshold generator, which adds to the PEAK-voltage a DC-dependent threshold VTH. Both signals, RECT
and PEAK+VTH are fed to a comparator which triggers a re-triggerable monoflop. The monoflop's output acti-
vates the sample-and-hold circuits in the signalpath for the selected duration
11.2 Noise Controlled Threshold Adjustment (NCT)
There are mainly two independent possibilities for programming the trigger threshold:
1. the low threshold in 8 steps (bits D1 to D3 of the noiseblanker-byte I)
2. and the noise adjusted threshold in 4 steps (bits D4 and D5 of the noiseblanker-byte I, see Figure 22).
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相關(guān)代理商/技術(shù)參數(shù) |
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| TDA7405_04 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:EQUALIZER CARRADIO SIGNAL PROCESSOR |
| TDA7405TR | 功能描述:處理器 - 專門應(yīng)用 EQUALIZER CAR RADIO SIGNAL PROCESSOR RoHS:否 制造商:Freescale Semiconductor 類型:Multimedia Applications 核心:ARM Cortex A9 處理器系列:i.MX6 數(shù)據(jù)總線寬度:32 bit 最大時鐘頻率:1 GHz 指令/數(shù)據(jù)緩存: 數(shù)據(jù) RAM 大小:128 KB 數(shù)據(jù) ROM 大小: 工作電源電壓: 最大工作溫度:+ 95 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MAPBGA-432 |
| TDA7406 | 功能描述:音頻 DSP Car Radio Signal RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
| TDA7406T | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:CAR RADIO SIGNAL PROCESSOR |
| TDA7406TR | 功能描述:音頻 DSP INFOTAINMENT SIGNAL RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
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