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seemoo-lab / nexmon_csi

Channel State Information Extraction on Various Broadcom Wi-Fi Chips
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Separating out signals from different antennas #59

Closed bachejames closed 4 years ago

bachejames commented 4 years ago

Hey! Thanks again for the awesome tool :)

I am looking to estimate the angle of arrival of signals by separately analysing the signal received by each of the Asus RT-AC86U's three antennas. Here is my setup: Receiver: Asus RT-AC86U coremask: -C 3 nssmask: -N 1 Code to identify from which antenna the signal is arriving at: from here

This setup is giving me a core value alternating between 0 & 1, and a constant rxss value of 0. I was however expecting a core value alternating between values: 0, 1 and 2 representing the signal received from each of the three antennas in turn.

I'm guessing that it's because I don't properly understand the coremask and nssmask settings correctly. My current understanding is: The coremask value represents the number of antennas that should record data, however this hypothesis is inconsistent with me receiving values of only 0 or 1 rather than 0, 1 or 2. The nssmask value represents the number of spatial streams to capture - and am guessing this means that this value should match the number of antennas the transmitter has (as long as it supports that number of streams).

I'm also a little confused by the fact that in the makecsiparams -h readme, it seems to indicate that these two values should be inputted in binary format, however all the examples I've seen on GitHub just use the decimal 1.

Many thanks for your help!

mzakharo commented 4 years ago

well, the word 'mask' -> means that each bit in a value represents an antenna. 0x1 -> 1 . 0x3 -> 2 bits -> 2 antennae, 0x7 -> 3 bits -> 3 antenna. Hope this helps! You can even do something like 0x4 -> antenna 3 only, or something exotic like 0x5, which is is antenna 1 and 3.

Here is more info: https://en.wikipedia.org/wiki/Mask_(computing)

jlinktu commented 4 years ago

Hi,

coremask and nssmask do not only set the number of cores and streams to use but also specify of what cores and streams csi shall be extracted. Values for both -C and -N can be any number between 1 and 15, thus all 4 bit combinations excluding 0, where the bits set to 1 indicate the indices of the cores or streams to extract from.

If you want to extract of the stream with index 0 of cores with indices 0, 1 and 2 you need to set -C 7 and -N 1. Decimal 7 equals to binary 0111, thus setting bits for core 3 to 0, core 2 to 1, core 1 to 1 and core 0 to 1.

Btw. the rt-ac86u should actually have four antennas, one being hidden inside the case.

bachejames commented 4 years ago

Very many thanks @jlinktu and @mzakharo, really appreciate the super helpful, very speedy replies.

mikeWangJC commented 4 years ago

@bachejames hi, buddy I also meet the similar problem. I cannot collect CSI data with three antennas of Asus RT-AC86U simultaneously, via

./makecsiparams -c 149/80 -C 7 -N 1 MAc-address -b 0x80

Do you have any suggestions? Thank u so much.

bachejames commented 4 years ago

Hey @mikeWangJC I haven't actually tried using all three antennas, but from my limited knowledge I can only suggest experimenting with turning on and off different antennas and seeing which provide the readout you are hoping for.

For example, perhaps instead of 0111 ie. -C 7, the right combination may be 1110 ie. -C 14.

mikeWangJC commented 4 years ago

@bachejames thank you so much for ue suggestion. BTW, I want to form a transceiver pair to collect CSI data. Do you know how to control the bandwidth and frequency of the signal?

bachejames commented 4 years ago

I don't I'm afraid, sorry @mikeWangJC

matthiasseemoo commented 4 years ago

https://github.com/seemoo-lab/wisec2017_nexmon_jammer_demo_firmware/blob/master/src/ioctl_5xx.c#L489 https://github.com/seemoo-lab/wisec2017_nexmon_jammer_demo_firmware/blob/master/src/ioctl_5xx.c#L489

On 16. May 2020, at 17:59, bachejames notifications@github.com wrote:

I don't I'm afraid, sorry @mikeWangJC https://github.com/mikeWangJC — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/seemoo-lab/nexmon_csi/issues/59#issuecomment-629667402, or unsubscribe https://github.com/notifications/unsubscribe-auth/ACZ773T3JP42QVEPIUNU5WLRR2Z4ZANCNFSM4MBEYPDQ.

yujianyuanhaha commented 4 years ago

Hi,

coremask and nssmask do not only set the number of cores and streams to use but also specify of what cores and streams csi shall be extracted. Values for both -C and -N can be any number between 1 and 15, thus all 4 bit combinations excluding 0, where the bits set to 1 indicate the indices of the cores or streams to extract from.

If you want to extract of the stream with index 0 of cores with indices 0, 1 and 2 you need to set -C 7 and -N 1. Decimal 7 equals to binary 0111, thus setting bits for core 3 to 0, core 2 to 1, core 1 to 1 and core 0 to 1.

Btw. the rt-ac86u should actually have four antennas, one being hidden inside the case.

May I know the concept of core, what does it stand for? @jlinktu

The nssmask is more clear to me, for 2 router, each have 4 anttennas, there could be at most 4*4 = 16 spatial stream.