Hello,
I have several questions regarding IQ sampling and a system of X310 with 2 UBX-160 daughterboards and PCIe 10GigE (through SFP+) for each channel.
I know I have many questions, I try to understand my system the best I can (:
Thanks a lot in advance!
1. Is my attached block diagram correct for a single UBX-160 , single motherboard and single FPGA? it includes:
- UBX-160 daughterboard with 80MHZ LPF for each channel(I,Q).
-USRP motherboard with
ADC(200Ms/Sec) and DAC(800MS/Sec) for each channel (I,Q)
I have found only a complete block diagram of USRP 2920 and not of USRP X310. So I modify it.
2. What is the sample rate of the DUC and the DDC in the FPGA?
3. Can a single UBX-160 receive 2 channels (RX1 and RX2) at same time a 160MHz analog bandwidth for each channel? so I can totally receive 160*2=320MHz analog bandwidth for a single UBX-160? or will the host performance (200MHz for a single PCIe 10GigE cable) limit it?
4. In the case of X310 with 2 UBX-160 daughterboards and 2 PCIe 10GigE cables ( one for each channel), how many channels can I receive at the same time with 160MHz analog bandwidth for each channel?
What is the total analog BW in this case?
5. If the ADC on the motherboard has a sampling rate = 200MHz, then what is the maximal bandwidth of the signal that it can sample? Is it 100MHz?
6. Does IQ sampling not violate Nyquist–Shannon sampling theorem, because the for a single RX channel on a single UBX-160, the Fs =200MHz of the ADC is larger than 2*BW of each I,Q channel ( 80MHz for each I,Q channel after the LPF)?
7.Does by applying IQ sampling I can actually double my bandwidth and double the data amount? Does in UBX-160 it helps increase analog bandwidth from 80MHz to 160MHz because we have 2 channels(I,Q) with 80MHz BW each with different information at each channel , right?
I refer to your website:
The ADC rate on each analog RX channel is 200 MS/s quadrature, which provides a theoretical analog bandwidth of approximately 80% of the Nyquist bandwidth of +/- 100 MHz (+/- 80 MHz around the center frequency). The resulting maximum
theoretical analog bandwidth is 160 MHz. The actual analog bandwidth may be reduced due the RF daughterboard selected.
8. So is this the reason why in IQ sampling we can say bandwidth = sampling rate? Because for the IQ demodulator, there are 2 channels (I,Q) , each channel has a bandwidth of 80MHz and together I+jQ = 160MHz, is that correct? so the analog bandwidth = 80-100% of the samp rate for IQ sampling, right?
9. If I want to receive a RF signal with BW= 160MHz in a single RX channel in a single UBX-160, should I put a samp rate of 200MHz in my GNURadio block?
If samp rate= BW for IQ sampling, I guess the answer is yes.
References:
