Hello, guys

I am doing some test of **Fmcdaq2** through **ADI oscilloscope**, I have found that the default sampling frequency of both ADC and DAC are set at **1GHz,** and the output frequency of DAC is **500MHz**. I loaded a file which is a * 16QAM* signal, and got the

*like below,*

**constellation diagram**Then I checked the * I/Q signal *in

*like these, which are irregular waveforms (of course they should be)*

**Time Domain**Here are my questions:

1. What's the **DAC output frequency** for each bit data? Is it still **500MHz**? Since I counted the bit number,which is 25, each 0.05us.

2. Since the file** Ioaded** is generated from matlab (attached below), are the waves I checked already added to **carrier waveform signals** which are * cos(wt)* for

**I channel**and

**) for**

*sin(wt***Q channel**? (I am sorry this may be a stupid question but wondering the answer.)

Hope anyone with experience can help me or give me a little hint.

Thank you so much!!!!

1. What's the

DAC output frequencyfor each bit data? Is it still500MHz? Since I counted the bit number,which is 25, each 0.05us.[answer]: It depends on the register settings. If interpolation is being used (reg 0x112 - default setting is 2x interpolation), then that has to be accounted for. DAC rate = DataRate x Interpolation factor. DataRate (fdata) = Input clock (at CLK input pin) / RefDivFactor (0x08C[2:0])

2. Since the file

Ioadedis generated from matlab (attached below), are the waves I checked already added tocarrier waveform signalswhich areforcos(wt)I channeland) forsin(wtQ channel? (I am sorry this may be a stupid question but wondering the answer.)[answer]: the the 16QAM test pattern includes the carrier.