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參數(shù)資料
| 型號： | LV2700V |
| 廠商： | Sanyo Electric Co.,Ltd. |
| 英文描述： | Spread Spectrum Communications IC(頻譜擴展通訊芯片) |
| 中文描述： | 擴頻通信集成電路（頻譜擴展通訊芯片） |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 343K |
| 代理商： | LV2700V |
Optimal control (tracking control)
After the initial acquisition is completed, the PN code synchronization condition is maintained by the PLL. This is
because, in the LV2700V, since a system configuration is adopted that maintains phase synchronization between the
carrier wave and the PN clock, the PN code synchronization is maintained as long as the PLL is locked to the carrier
wave. However, since the position of the synchronization point within the ±1 chip range is not definite, a control
circuit is provided to track to the best synchronization point. Fig. 6 shows the block diagram of the optimal control
circuit. In this optimal control circuit, three PN codes delayed successively by 1/4 chip are used as the PN code for
unspreading successively. In other words, these correspond to the reference phase P, the early phase E, and the late
phase L. Next, the correlation output is obtained for each PN code by the envelope detector circuit. These correlation
outputs are successively compared and the phase of the PN code is controlled so that the correlation output at the
reference phase P is larger than the correlation values at the other PN codes. For example, when the PN codes at E, P,
and L are at the positions shown in Fig. 7, since the correlation value at L is larger than that at the reference P, the
phase of the PN code is controlled by gradually delaying until finally the position of P is at the point at which the value
of the autocorrelation function becomes a maximum.
Since this optimal control operation is being carried out continuously, the PN synchronization condition is maintained
always at the best position even when the reception condition varies by large amounts.
Fig. 6 Optimal control circuit
Fig. 7
No. 5651-12/20
LV2700V
SS Input
Sync
detector
Control
circuit
After optimal control operation
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