[casper] wide_band_real fft simulation problem of tut3

[Wang Jinqing]

Hi,

I can run the tut3.mdl,but I found the simulation result of  wide_band fft is 
not correct. For example I have generate a sine (freq= 1/4pi)wave input the 
KaADC ,I found the polyphase output sine wave is still ok on the scope,  but 
after the wide_band_real fft ( after real and image parts seperation) and power 
I even can't find the corresponding spectrum line. There're many messy signals 
on the spectrum. It seems that the fft core not works well in simulation. Does 
someone run into this problem?

Best Regards.

Oliver Wang. 

Re: [casper] wide_band_real fft simulation problem of tut3

[G Jones]

When you are simulating, do you have the fftshift set appropriately? A pure
sine wave will be the worst case for bit growth and overflow, so you'll
want an fftshift of 0x I think.
On Nov 2, 2014 2:11 AM, Wang Jinqing jqw...@shao.ac.cn wrote:

 Hi,

 I can run the tut3.mdl,but I found the simulation result of  wide_band fft
 is not correct. For example I have generate a sine (freq= 1/4pi)wave input
 the KaADC ,I found the polyphase output sine wave is still ok on the scope,
  but after the wide_band_real fft ( after real and image parts seperation)
 and power I even can't find the corresponding spectrum line. There're many
 messy signals on the spectrum. It seems that the fft core not works well in
 simulation. Does someone run into this problem?

 Best Regards.

 Oliver Wang.

Re: [casper] wide_band_real fft simulation problem of tut3

[Jack Hickish]

Can I add to this - do you simulate a sync pulse input, and wait an
adequate time to see it show up on the block output?

Jack
On 2 Nov 2014 12:50, G Jones glenn.calt...@gmail.com wrote:

 When you are simulating, do you have the fftshift set appropriately? A
 pure sine wave will be the worst case for bit growth and overflow, so
 you'll want an fftshift of 0x I think.
 On Nov 2, 2014 2:11 AM, Wang Jinqing jqw...@shao.ac.cn wrote:

 Hi,

 I can run the tut3.mdl,but I found the simulation result of  wide_band
 fft is not correct. For example I have generate a sine (freq= 1/4pi)wave
 input the KaADC ,I found the polyphase output sine wave is still ok on the
 scope,  but after the wide_band_real fft ( after real and image parts
 seperation) and power I even can't find the corresponding spectrum line.
 There're many messy signals on the spectrum. It seems that the fft core not
 works well in simulation. Does someone run into this problem?

 Best Regards.

 Oliver Wang.