Dear ,
As the attachment show in WaveVision 5 tool .
What's mean about 4095 counts in Y-axis ? is voltage level or what ?
How should I calculate the frequency of the signal ?
Best Regards,
Jean
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Dear ,
As the attachment show in WaveVision 5 tool .
What's mean about 4095 counts in Y-axis ? is voltage level or what ?
How should I calculate the frequency of the signal ?
Best Regards,
Jean
Hello Jean,
The screenshot you sent is the time domain view which has a y-axis of codes. For the ADC12D1800RF, this is a 12 bit device so the y-axis should range from 0 to 2^12-1 or 4095. Your cursor is showing that the input signal has a code value of 4095 which means that the input signal is at or above the maximum range of the ADC. You should reduce your input signal amplitude so that you do not damage the device. Please refer to the datasheet for the absolute maximum ratings.
The box you highlighted in yellow shows the clock frequency that the ADC is running at. To get more information about the input signal you can switch to FFT view and open the FFT Readouts tab located at the left of the screen. I've shown what this looks like below with an input signal of 497.42MHz
For more information about WaveVision5, please see the user's guide located at the following address: http://www.ti.com/tool/wavevision5
Hello Luke :
I have reduced the input amplitude as the attachment show . (sampling & value2.PNG)
But I still have a doubt about meaning of "code" .
How do I transform the "code" to "power level - mW" ?
Best Regards,
Jean
Hello Jean,
In order to convert codes to mW, you will need to know the full scale voltage range of the ADC and the resistive load.
In WaveVision, you can click the "Registers" tab on the right side of the screen and select I-Channel or Q-Channel accordingly to see the fullscale voltage in mV shown below.
This value is adjustable from 600mV to 1000mV with 800mV being the default. A signal with a peak-to-peak value of 4096 codes would correspond to a full scale signal of 800mV. In the example above, the signal has a peak-to-peak value of 3685 codes and would therefore correspond to a 3685/4096*800mVpp = 719.7266mVpp. To convert to Watts, it is Vrms^2/Z where Z in this case is 100Ω differential, giving a total power at the input of [0.7197Vpp/(2*sqrt(2))]^2/100Ω = 0.647 mW. You can additionally convert this to dBm with 10log(P/1mW) = -1.887dBm.
Hello Luke :
Another questions.
1. When I make Anritsu MP1800A equipment to send out 2.5GHz signal to ADC12D1800RFRB board , but the WV5 shows the signal is 1.25GHz. Why ?
See the attachments .
2. How could I accumulate the signal in WV5 ?
Thanks
Jean