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AD9361-FMCOMMS2 Transmitter spurious

Question asked by Raveendra on Jun 11, 2014
Latest reply on Jan 21, 2015 by rgetz



I am using AD-FMCOMMS2 along with ZC702 as you suggested.

I am testing this board with linux pre-build image, i am operating device with the platform provided by analog devices.

Initially i started testing with transmitter and i operated device operated with below conditions

LO Tuned Freq: 2450 MHz

DDS mode: One CW tone

Single tone frequency: 0.999 MHz

Scale: 0.062500

with this setting i observed spectrum with 2451 MHz as main frequency along with spurious as mentioned below.

Total output level observed as : -10.34 dBm

Spurious @ 1 MHz offset: -47.36 dBc

Spurious @ 2 MHz offset: 57.65 dBc

Spurious @ 4 MHz offset: 67.4 dBc

Spurious @ -4 MHz offset: 67 dBc

other than this spurious i observed there are many spurious observed like +/- 94 & 320 KHz spurious and these are also dominating in spectrum.

And i am not getting enough transmitter output and then i started increasing the scale level under DDS menu, when increased the scale level output power increasing and as well as the spurious mentioned above are also increasing non-linearly.


As you told this problem i observed when i am testing FMCOMMS2 with my hardware also, then you told us to use API drivers or Zynq boards to get better performance. So please kindly look in to this issue and help me to solve this issues.


Here i attached couple of images captured in spectrum and few images(062-064) shows with respect scale level of DDS from (0.0625 to 0.5).

Image 67 shows the KHz spurious and image 59 shows the spectrum with more bandwidth when scale @ 0.0625.


Please tell how to increase output power level and how to maintain these spurious level as much as low?