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发表于 2011-10-25 11:41:13
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回复【57楼】PSIR
我上来报告一下近况,信号源部分我改用带通滤波器将方波转成正弦波当测试信号,
目前在挑战200khz,因为频率做越高觉得测量误差越大,尚不知原因为何?
有想到的话再来分享心得。
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那你的方波产生方案呢?
我发现的ad9834资料中有一段话不好理解啊
The 80C51/80L51 outputs the serial data in an LSB-first format. The AD9834 accepts the MSB first (the four MSBs being the control information, the next four bits being the address, and the eight LSBs containing the data when writing to a destination register). Therefore, the transmit routine of the 80C51/80L51 must take this into account and rearrange the bits so that the MSB is output first.
这难道是说80C51单片机要给ad9834送频率数据的话,必须先送28位频率字的高14位吗?那我以前的频率难道全送反啦?比如要设置10KHZ的正弦波,要是反过来的话,就变成输出大概3MHZ的正弦波啦,晕~~~~~
还有这一段
COMPARATOR
As the comparator input is ac-coupled, to operate correctly as a zero crossing detector, it requires a minimum input frequency of typically 3 MHz. The comparator output is a square wave with an amplitude from 0 V to DVDD.
这是说AD9834内置的比较器只能接受3MHZ以上的频率的正弦波吗?那么它就只能输出3Mhz以上的方波啦。 |
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