Dear USRP Mailing List Members, We have been experimenting with the X410 for same time to support dual-band reception, specifically at 3.7 GHz and 6.8 GHz. After several observations*, it is still not clear how X410/UHD decides which filter to use in the IF1 and IF2 stages. We have the following questions:
1. Can we force the X410 to use a specific IF1 and/or IF2 filter stage? Essentially, can we program the states of Sw5, Sw6, Sw7, and Sw8? 2. How can we ensure that IF1_3 or IF1_4 is used for 6.8 GHz RF? 3. Where and how can we check the magnitude responses of RF, IF1, and IF2 filters? 4. How can we ensure that, after each initialization, the X410 selects the same filter combination at RF, IF1, and IF2 stages for the same input frequency but different Rx Reference Power settings? Please do not hesitate to contact me if anything is unclear or if further clarification is needed. Best regards, Altug Kaya Research Associate Wireless Communications and Networks [email protected]<mailto:[email protected]> Tel +49 30 31002-680 Fraunhofer Institute for Telecommunications Heinrich Hertz Institute, HHI Einsteinufer 37, 10587 Berlin, Germany www.hhi.fraunhofer.de<http://www.hhi.fraunhofer.de> *P.S.1: I attached some of our observations in detail below: Observation#1 * Freq1: 3.7 GHz and Freq2: 6.8 GHz * LO1 was automatically bypassed. LO2 was manually set to ~5.5 GHz * Thus, Freq1 was downconverted to IF2 of ~1.8 GHz. UHD automatically selected the IF2_2 branch. * Thus, Freq2 was downconverted to IF2 of ~1070 MHz. UHD automatically selected the IF2_1 branch. Observation#2 * Freq1: 3.7 GHz and Freq2: 6.8 GHz * LO1 was automatically bypassed. LO2 of Ch1 was set to ~5.17 GHz and LO2 of Ch2 was set to ~5.33 GHz manually. * Thus, both RFs were downconverted to same IF2 of ~1.47 GHz. * However, the signals passed through different filters at IF2 stage, even though their IF2 were the same. P.S.2: There is a typo on ZBX Daughterboard webpage. IF1 range of the ADC should be written in units of GHz.
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