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Hi, sir,
I was trying to build a 2Tx-8Rx Antenna array system to measure the CSI among each Tx-Rx pair.
Hardware setup: three WARP V3 platform with WARPLab 7.7. The 2 WARP V3 board are with two daughterboards, and another WARP V3 board has only two radios:
I'm a freshman here and have the following questions:
1: For the two Rx WARP V3 board, shall I sync time and signal?
2: Shall I trigger the buffer baseband and the AGC of all three WARP boards with Ethernet, or just like the 8x2 array example, triggering the Tx board and the first Rx board, then allow the first Rx board to trigger the second Rx board using the debug header.
3: if I just have two WARP V3 board (each with four radios), and change it to 1Tx-7Rx, how can I make it? Also, is there any significant interference between Tx and other three Rx radios on the same board here, since I feel it like a Full-duplex.
Thanks for your help!
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1) If you want to use the two 4-antenna nodes as a logical 8-antenna node you should definitely synchronize the reference clocks. You should also connect digital I/O to synchronize triggers across the nodes.
2) You should distribute triggers via digital I/O for any nodes configured as part of an array. Triggers via Ethernet have inherent jitter - the nodes will receive and process the broadcast trigger packet at different times. The range of offsets depends on your Ethernet switch and network topology (we've seen offsets of a few nsec up to 10's of nsec).
3) The inter-radio isolation on one board depends on the pair of interfaces and whether antennas are connected. When the interfaces are terminated into 50 ohms the isolation between neighboring interfaces (A-to-B or C-to-D) is around 50dB; isolation between the on-board and FMC interfaces is higher. However if you have antennas connected and the antennas are close together, the inter-antenna path will likely dominate.
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Thanks so much Murphpo. Got it, I will try.
murphpo wrote:
1) If you want to use the two 4-antenna nodes as a logical 8-antenna node you should definitely synchronize the reference clocks. You should also connect digital I/O to synchronize triggers across the nodes.
2) You should distribute triggers via digital I/O for any nodes configured as part of an array. Triggers via Ethernet have inherent jitter - the nodes will receive and process the broadcast trigger packet at different times. The range of offsets depends on your Ethernet switch and network topology (we've seen offsets of a few nsec up to 10's of nsec).
3) The inter-radio isolation on one board depends on the pair of interfaces and whether antennas are connected. When the interfaces are terminated into 50 ohms the isolation between neighboring interfaces (A-to-B or C-to-D) is around 50dB; isolation between the on-board and FMC interfaces is higher. However if you have antennas connected and the antennas are close together, the inter-antenna path will likely dominate.
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By the way, sir, how to choose the two radios on the daughterboard? is it called variable.RF_C and variable.RF_D as the two radios on the motherboard (variable.RF_A and variable.RF_B)?
murphpo wrote:
1) If you want to use the two 4-antenna nodes as a logical 8-antenna node you should definitely synchronize the reference clocks. You should also connect digital I/O to synchronize triggers across the nodes.
2) You should distribute triggers via digital I/O for any nodes configured as part of an array. Triggers via Ethernet have inherent jitter - the nodes will receive and process the broadcast trigger packet at different times. The range of offsets depends on your Ethernet switch and network topology (we've seen offsets of a few nsec up to 10's of nsec).
3) The inter-radio isolation on one board depends on the pair of interfaces and whether antennas are connected. When the interfaces are terminated into 50 ohms the isolation between neighboring interfaces (A-to-B or C-to-D) is around 50dB; isolation between the on-board and FMC interfaces is higher. However if you have antennas connected and the antennas are close together, the inter-antenna path will likely dominate.
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By the way, sir, how to choose the two radios on the daughterboard? is it called variable.RF_C and variable.RF_D as the two radios on the motherboard (variable.RF_A and variable.RF_B)?
Right - see the WARPLab user guide for details
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