ad9361 filter design wizard

Hi,

I want to design a low pass filter using ad9361 filter design wizard having baseband sampling rate 240 ksps.

But as soon as I am entering 240 kHz, it is taking 521KHz by default.

Till 521 KHz sampling rate I am able to design filters but not below that that.

Kindly help me.

Top Replies

  • 0
    •  Analog Employees 
    on Aug 10, 2020 3:55 PM 3 months ago

    AD9361 has a minimum sample rate of 25000000/48 (520.3333 kHz). 

    -Travis

  • Hi Travis,

    I have the same question, but as you said the minimum sampling rate is 520.3333kHz, I designed the filter with data clock as 520841.

    I saved the coefficients as .c files and copied the generated AD9361_TXFIRConfig and AD9361_RXFIRConfig structure to main.c of ad9361 No-Os driver and changed the rx and tx clock paths frequencies in default_init_param structure with clock paths generated from ad9361 filter wizard.

    When running the code, I see that tx_samp_freq=2083364 but not 520841. Help me understand this.

    and how do I set the tx_samp_freq=520841.

    Best Regards

    Adepu

    // Data Sample Frequency = 520841 Hz
    
    AD9361_RXFIRConfig rx_fir_config = {
    	3, // rx
    	-12, // rx_gain
    	4, // rx_dec
    	{139,-49,221,-25,122,-130,-141,-402,-476,-653,-630,-606,-398,-188,104,301,439,396,247,-33,-309,-542,-607,-505,-212,165,544,774,790,538,91,-448,-893,-1106,-972,-510,182,891,1398,1499,1122,319,-689,-1607,-2109,-1979,-1164,161,1642,2806,3218,2605,980,-1323,-3686,-5342,-5557,-3835,-67,5386,11742,17937,22858,25579,25579,22858,17937,11742,5386,-67,-3835,-5557,-5342,-3686,-1323,980,2605,3218,2806,1642,161,-1164,-1979,-2109,-1607,-689,319,1122,1499,1398,891,182,-510,-972,-1106,-893,-448,91,538,790,774,544,165,-212,-505,-607,-542,-309,-33,247,396,439,301,104,-188,-398,-606,-630,-653,-476,-402,-141,-130,122,-25,221,-49,139}, // rx_coef[128]
    	128, // rx_coef_size
    	{800011800,25000368,8333456,4166728,2083364,520841}, // rx_path_clks[6]
    	434756 // rx_bandwidth
    };
    
    AD9361_TXFIRConfig tx_fir_config = {
    	3, // tx
    	0, // tx_gain
    	4, // tx_int
    	{55,-53,40,-124,-125,-316,-400,-580,-646,-711,-634,-506,-263,-10,255,424,491,401,201,-84,-351,-540,-565,-423,-126,234,562,738,700,429,-6,-490,-865,-1006,-833,-372,266,890,1300,1333,935,178,-733,-1523,-1915,-1730,-942,274,1589,2583,2879,2252,739,-1344,-3433,-4846,-4937,-3279,203,5173,10925,16508,20930,23372,23372,20930,16508,10925,5173,203,-3279,-4937,-4846,-3433,-1344,739,2252,2879,2583,1589,274,-942,-1730,-1915,-1523,-733,178,935,1333,1300,890,266,-372,-833,-1006,-865,-490,-6,429,700,738,562,234,-126,-423,-565,-540,-351,-84,201,401,491,424,255,-10,-263,-506,-634,-711,-646,-580,-400,-316,-125,-124,40,-53,55}, // tx_coef[128]
    	128, // tx_coef_size
    	{800011800,25000368,8333456,4166728,2083364,520841}, // tx_path_clks[6]
    	1253625 // tx_bandwidth
    };
    

  • 0
    •  Analog Employees 
    on Sep 4, 2020 7:58 PM 2 months ago in reply to adepu
    When running the code, I see that tx_samp_freq=2083364 but not 520841.

    How are you reading this back? How are you enabling the filters?

    -Travis

  • Hi,

    I am checking the sampling frequency with the command tx_samp_freq?, and enabling the filters with tx_fir_en=1. attached the commands executed, Please ignore the 'Invalid command' part.

    regards

    Surender

  • +1
    •  Analog Employees 
    on Sep 10, 2020 5:41 PM 2 months ago in reply to adepu

    Please use the ad9361_trx_load_enable_fir function in your code to enable the filters.

    -Travis