On 28 March 2017 at 23:23, Bastian Bloessl <address@hidden> wrote:
Warm regards,Hi,
On 03/28/2017 06:43 PM, Anshul Thakur wrote:
> With this, two parts work independently:
> - I am able to Rx packets from Wifi using wifi_rx.py (however, it works
> best only when I use it from the shell script provided. That is strange!).
> - I am able to Tx packets from SDR which are detected by a Wifi card in
> monitor mode.
Great.
>
> However, When one SDR transmits and the other is receiving, I am not
> able to receive the packets sent by the SDR.
> - I tried it using wifi_rx shell script on one, and wifi_tx.py on the
> other. PDUs from other Wifi Devices are detected.
> - I also tried putting a direct line between the Tx of one SDR to Rx of
> the other. Still no reception.
I think you should try to find out where things go wrong. Are frames
detected? Is frame detection triggered all the time? Does the receiver
sync on the frames (i.e., looks the constellation diagram somehow OK)?
etc., etc.
Frame equalization is being called whenever there is a transmission. Here is one representative output:
FRAME EQUALIZER: input 89 output 48
SHORT copied 16
SHORT copied 8
LONG ninput[0] 916 ninput[1] 1236 noutput 609 state 1
SHORT copied 4
produced : 609 consumed: 769
LONG ninput[0] 271 ninput[1] 591 noutput 256 state 1
produced : 223 consumed: 271
And here is an atypical one:
FRAME EQUALIZER: input 64 output 48
epsilon: 1.01009e-05
Encoding: 12 Mbit/s INFO: encoding: 4 - length: 2053 - symbols: 172
SHORT copied 4096
FRAME EQUALIZER: input 18 output 12
FRAME EQUALIZER: input 6 output 6
SHORT copied 1746
LONG ninput[0] 2349 ninput[1] 2669 noutput 4096 state 0
produced : 0 consumed: 320
LONG ninput[0] 7871 ninput[1] 7871 noutput 4096 state 1
SHORT copied 320
produced : 4096 consumed: 5247
LONG ninput[0] 2944 ninput[1] 2944 noutput 2047 state 1
produced : 2047 consumed: 2559
LONG ninput[0] 385 ninput[1] 705 noutput 256 state 1
INFO: frame start at 61387
produced : 256 consumed: 320
LONG ninput[0] 65 ninput[1] 385 noutput 64 state 1
produced : 49 consumed: 65
SHORT Frame!
SHORT copied 3343
FRAME EQUALIZER: input 64 output 48
epsilon: -4.06662e-06
SIGNAL: wrong parity
Here is a screenshot. I am transmitting using BPSK (1/2) scheme.
Maybe the BladeRF also has some calibration routines for TX DC offset
(which, I think, could make things worse for the receiver with line of
sight).
I haven't recalibrated the Tx DC Offset as I found it to be close to zero (as per what they have described on the Wiki Page). The above output is for RF transmission rather than a cabled Line of Sight.
You could also test different RX/TX gains and parameters for the padding
block (I don't have a BladeRF, so I have no experience). Also assert
that there are no overruns or underruns.
I altered the values of gains and padding values (I increased the padding values). That didn't seem to help.
Best,
Bastian
Anshul