indistinguishable CSI waveform on NEXUS 5

[yujianyuanhaha]

greetings,

for those collecting CSI on NEXUS5, have anyone meet the problem that the CSI of the four spatial stream (assume the TX is ASUS router with 4 antennas, and RX/ Sniffer is NEXUS 5 so there are 4x1 spatial stream) is pretty the same? Below is the illustration of these waveforms

I assume they should be different since my CSI collection on ASUS router, all 4x4=16 spatial stream's CSI is different from each other.

I even install the external antennas to make the space between each TX antennas larger, but the waveform still pretty close.

Anyone kindly could look into the problem a bit? @DanielAW @schmittner @matthiasseemoo @zeroby0

Thanks in advance.

Note:

1. the way I compute the NSS is

   if strcmp(DEVICE,'ASUS')
       core = bitand(payloadbytes(56),3); %
       rxss = bitand(bitshift(payloadbytes(56),-3),3);
       Nss(k) = core*4 + rxss; 
   else
      % payloadbytes(55)
      % 0 8 16 24
       Nss(k) =  round( payloadbytes(55)/8);  
   end

[yangtat]

On the Nexus 5, the CSI of the four spatial streams I collected are almost identical too. But on the Nexus 6P I can get different ones.

[yujianyuanhaha]

@yangtat thanks, that might be a solution however, the Tx-by-RX (here is 4 x 1 ) spatial stream, I have separate the antenna as I can ...