AFE5809EVM: AFE5809EVM DEMOD 输出不正常

Hi Eric,

I recommend you to try to go step by step. First you can bring up the AFE without demod. Dont enable the demod and try to digest the output signal behavior. First you can calculate the total TGC path gain (it will LNA gain + PGA gain + TGC attenuation decided by Vcon) and based on the input signal, you will be able to calculate output signal swing. The ADC full scale swing is 2Vpp. For example if TGC gain is say 40dB then for getting 2Vpp at the output, you have to apply 20mVpp signal only. If you give signal more than this then signal chain will overload and you will see clipped output. In case you dont want to apply external Vcon then try out with DTGC attenuation setting given in the GUI.

Once you are comfortable with signal transfer function without demod, then enable the demod and based on mixer and decimation filter setting, the signal FFT will chnage. So you need to analyze first what is expected signal at the device output based on what setting you apply for mixer and decimation filter and then capture the device data. Also you have to separate the I/Q phase data in the GUI to make sense out of it.

Thanks

Regards,

Shabbir

Hi Shabbir,

picture 1 is my TGC gain configuration .and the input signal is a burst sinus signal with 10 cycles and it is amplitude about 50 mV. the afe5809 LVDS output without demod just like the picture 2,

for the output wave,it is not  so good because i use many cable instead of SMA cable to connect the evm so i think it normal. but when i want to test the demod ,the out put is so bad ,please check it from picture 3.

Hi,

Are you apply TX_TRIG to the device and apply hardware trigger for capture? To separate the data, SYNC word is required. If TX_TRIG is not applied then SYNC word wont appear in LVDS data and data separation wont work.

Also send me the steps you are following to configure the demod.

Regards,

Shabbir

Hi

I indeed apply the tx_trig signal from the AFG3102 (signal generator),and I enable the trigger mode of the afe5809evm ,this is what the tsw1400evm sampled data. And after i enable the demod mode the output just like this.

Hi,

This looks expected. Can you please show the separated data (Zoomed wavefrom)? Also share demod settings.

Thanks!

Regards,

Shabbir

Hi Shabbir

This is the separate data.

The demos setting is decimation=4,I just test it by refer the Ti AFE5809evm user guide. All the setting I did just as the same as it.

www.ti.com.cn/.../slou338a.pdf

Thanks.

Hi

I am not able to see the signal. Can you please zoom the time axis and show?

Regards,

shabbir