Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Bastian Bloessl]

On 06/04/2017 06:07 PM, Qurat-Ul-Ann Akbar wrote:
It does detect the correlation and start of frames in sync_Short 
block but data is not decoded probably because of high noise. 
If there are no overruns and your SNR is so incredibly bad that you 
cannot even detect the autocorrelation at the start of the frame, I 
would try a different SDR.


Best,
Bastian

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Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Qurat-Ul-Ann Akbar]

I have been doing this for a long time now and I have changed all these
parameters that you just mentioned in order to understand whats going on. I
have changed both the transmitter and receiver gain and set different
values but gain is not changing the SNR for some reason. It only works till
2.5 Mhz and at higher sampling rates data is not decoded at all. It does
detect the correlation and start of frames in sync_Short block but data is
not decoded probably because of high noise. I have also used different DC
offset values and that doesn't help either. The antennas are placed within
each other's LOS and I dont think interference should be a problem. And if
you have used Vert2450 antennas then I really dont understand whats the
problem.

On Sun, Jun 4, 2017 at 11:47 AM, Bastian Bloessl  wrote:

>
> On 06/04/2017 05:35 PM, Qurat-Ul-Ann Akbar wrote:
>
>> Then what could be the problem for a low SNR. The average power I see at
>> the receiver is -100 to -120 db and the signal is too distorted within
>> noise.
>>
>
> This can have many reasons (including gain, interference, DC offsets, LO
> leakage, etc etc.) I think it will take some more effort from your side to
> find out what's going wrong.
>
> You might find lots of helpful information on
> - wime-project.net/installation/
> - the GNU Radio Wiki
> - the mailing list archive
> - Stack overflow
>
>
>
>> And I watched your video on YouTube in which you were showing a demo of
>> the WiFi receiver. In that video you had big antennas and I don't think
>> those were Vert 2450.
>>
>
> If the video shows larger dipoles with cables, they were ECOM9-5500.
> Again, I don't believe that the antennas are your problem. I used the
> transceiver successfully with many different antennas, including the Vert
> 2450 that you are using.
>
> Best regards,
> Bastian
>
>
>
>
>> On Jun 4, 2017 11:21 AM, "Bastian Bloessl"  m...@bastibl.net>> wrote:
>>
>>
>>
>> On 06/04/2017 05:16 PM, Qurat-Ul-Ann Akbar wrote:
>>
>> I understand. But you didnt connect them directly to the USRP.
>> You used some cable to connect the two and had a stand for your
>> antenna. Can you tell me which cable was that ?
>>
>>
>> I have no idea what you are talking about. When I used the Vert
>> antennas, I connected them directly to the USRP.
>>
>> If you experience low SNR you'll probably not improve things if you
>> add cables between the SDR and the antenna. I doubt that the antenna
>> or cables are your problem.
>>
>> Best,
>> Bastian
>>
>>
>>
>>
>> On Jun 4, 2017 11:13 AM, "Bastian Bloessl" >  > >> wrote:
>>
>>  Hi,
>>
>>
>>  On 06/04/2017 04:25 PM, Qurat-Ul-Ann Akbar wrote:
>>
>>  Thank you for the explanation. Can you tell me which
>> antennas
>>  did you use for your experiments when you wrote your
>> paper?
>>  Because I think a major problem with my receiver is a
>> very low
>>  SNR because everything works fine with simulations.
>> Currently I
>>  am using Vert 2450 antenna with my USRP N210.
>>
>>
>>  I used the same setup with the Vert 2450 antennas.
>>
>>  Best,
>>  Bastian
>>
>>
>>
>>
>>
>>
>>  On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl
>>  
>> >
>>  
>> >
>>   Hi,
>>
>>   On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:
>>
>>   Hello,
>>
>>   How is the timing offset being handled in the
>> 802.11
>>  module. I
>>   see that the sync_long block does frequency
>> offset
>>  correction
>>   and the frame_equalizer block does the phase
>> correction
>>  but I
>>   dont understand where is the timing offset being
>>  handled. Can
>>   anyone tell me which algorithm is being used
>> to do that?
>>
>>
>>   The Sync Long block correlates the signal with the
>> known
>>  pattern of
>>   the long preamble to derive how the FFTs have to
>> be aligned
>>  in time.
>>
>>   Best,
>>   Bastian
>>
>>
>> -- Dipl.-Inform. Bastian Bloessl
>> CONNECT Center
>> Trinity College Dublin
>>
>> GitHub/Twitter: @bastibl
>> https://www.bastibl.net/
>>
>>
> --
> 

Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Bastian Bloessl]

On 06/04/2017 05:35 PM, Qurat-Ul-Ann Akbar wrote:
Then what could be the problem for a low SNR. The average power I see at 
the receiver is -100 to -120 db and the signal is too distorted within 
noise.


This can have many reasons (including gain, interference, DC offsets, LO 
leakage, etc etc.) I think it will take some more effort from your side 
to find out what's going wrong.


You might find lots of helpful information on
- wime-project.net/installation/
- the GNU Radio Wiki
- the mailing list archive
- Stack overflow




And I watched your video on YouTube in which you were showing a demo of 
the WiFi receiver. In that video you had big antennas and I don't think 
those were Vert 2450.


If the video shows larger dipoles with cables, they were ECOM9-5500. 
Again, I don't believe that the antennas are your problem. I used the 
transceiver successfully with many different antennas, including the 
Vert 2450 that you are using.


Best regards,
Bastian





On Jun 4, 2017 11:21 AM, "Bastian Bloessl" > wrote:




On 06/04/2017 05:16 PM, Qurat-Ul-Ann Akbar wrote:

I understand. But you didnt connect them directly to the USRP.
You used some cable to connect the two and had a stand for your
antenna. Can you tell me which cable was that ?


I have no idea what you are talking about. When I used the Vert
antennas, I connected them directly to the USRP.

If you experience low SNR you'll probably not improve things if you
add cables between the SDR and the antenna. I doubt that the antenna
or cables are your problem.

Best,
Bastian




On Jun 4, 2017 11:13 AM, "Bastian Bloessl"  >> wrote:

 Hi,


 On 06/04/2017 04:25 PM, Qurat-Ul-Ann Akbar wrote:

 Thank you for the explanation. Can you tell me which
antennas
 did you use for your experiments when you wrote your paper?
 Because I think a major problem with my receiver is a
very low
 SNR because everything works fine with simulations.
Currently I
 am using Vert 2450 antenna with my USRP N210.


 I used the same setup with the Vert 2450 antennas.

 Best,
 Bastian






 On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl
 
>
 

Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Qurat-Ul-Ann Akbar]

Then what could be the problem for a low SNR. The average power I see at
the receiver is -100 to -120 db and the signal is too distorted within
noise.

And I watched your video on YouTube in which you were showing a demo of the
WiFi receiver. In that video you had big antennas and I don't think those
were Vert 2450.

On Jun 4, 2017 11:21 AM, "Bastian Bloessl"  wrote:

>
>
> On 06/04/2017 05:16 PM, Qurat-Ul-Ann Akbar wrote:
>
>> I understand. But you didnt connect them directly to the USRP. You used
>> some cable to connect the two and had a stand for your antenna. Can you
>> tell me which cable was that ?
>>
>
> I have no idea what you are talking about. When I used the Vert antennas,
> I connected them directly to the USRP.
>
> If you experience low SNR you'll probably not improve things if you add
> cables between the SDR and the antenna. I doubt that the antenna or cables
> are your problem.
>
> Best,
> Bastian
>
>
>
>
>> On Jun 4, 2017 11:13 AM, "Bastian Bloessl"  m...@bastibl.net>> wrote:
>>
>> Hi,
>>
>>
>> On 06/04/2017 04:25 PM, Qurat-Ul-Ann Akbar wrote:
>>
>> Thank you for the explanation. Can you tell me which antennas
>> did you use for your experiments when you wrote your paper?
>> Because I think a major problem with my receiver is a very low
>> SNR because everything works fine with simulations. Currently I
>> am using Vert 2450 antenna with my USRP N210.
>>
>>
>> I used the same setup with the Vert 2450 antennas.
>>
>> Best,
>> Bastian
>>
>>
>>
>>
>>
>>
>> On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl
>> 
>> >> wrote:
>>
>>  Hi,
>>
>>  On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:
>>
>>  Hello,
>>
>>  How is the timing offset being handled in the 802.11
>> module. I
>>  see that the sync_long block does frequency offset
>> correction
>>  and the frame_equalizer block does the phase correction
>> but I
>>  dont understand where is the timing offset being
>> handled. Can
>>  anyone tell me which algorithm is being used to do that?
>>
>>
>>  The Sync Long block correlates the signal with the known
>> pattern of
>>  the long preamble to derive how the FFTs have to be aligned
>> in time.
>>
>>  Best,
>>  Bastian
>>
>>
> --
> Dipl.-Inform. Bastian Bloessl
> CONNECT Center
> Trinity College Dublin
>
> GitHub/Twitter: @bastibl
> https://www.bastibl.net/
>
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Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Bastian Bloessl]

On 06/04/2017 05:16 PM, Qurat-Ul-Ann Akbar wrote:
I understand. But you didnt connect them directly to the USRP. You used 
some cable to connect the two and had a stand for your antenna. Can you 
tell me which cable was that ?


I have no idea what you are talking about. When I used the Vert 
antennas, I connected them directly to the USRP.


If you experience low SNR you'll probably not improve things if you add 
cables between the SDR and the antenna. I doubt that the antenna or 
cables are your problem.


Best,
Bastian





On Jun 4, 2017 11:13 AM, "Bastian Bloessl" > wrote:


Hi,


On 06/04/2017 04:25 PM, Qurat-Ul-Ann Akbar wrote:

Thank you for the explanation. Can you tell me which antennas
did you use for your experiments when you wrote your paper?
Because I think a major problem with my receiver is a very low
SNR because everything works fine with simulations. Currently I
am using Vert 2450 antenna with my USRP N210.


I used the same setup with the Vert 2450 antennas.

Best,
Bastian






On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl

>> wrote:

 Hi,

 On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:

 Hello,

 How is the timing offset being handled in the 802.11
module. I
 see that the sync_long block does frequency offset
correction
 and the frame_equalizer block does the phase correction
but I
 dont understand where is the timing offset being
handled. Can
 anyone tell me which algorithm is being used to do that?


 The Sync Long block correlates the signal with the known
pattern of
 the long preamble to derive how the FFTs have to be aligned
in time.

 Best,
 Bastian



--
Dipl.-Inform. Bastian Bloessl
CONNECT Center
Trinity College Dublin

GitHub/Twitter: @bastibl
https://www.bastibl.net/

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Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Qurat-Ul-Ann Akbar]

I understand. But you didnt connect them directly to the USRP. You used
some cable to connect the two and had a stand for your antenna. Can you
tell me which cable was that ?

On Jun 4, 2017 11:13 AM, "Bastian Bloessl"  wrote:

> Hi,
>
>
> On 06/04/2017 04:25 PM, Qurat-Ul-Ann Akbar wrote:
>
>> Thank you for the explanation. Can you tell me which antennas did you use
>> for your experiments when you wrote your paper? Because I think a major
>> problem with my receiver is a very low SNR because everything works fine
>> with simulations. Currently I am using Vert 2450 antenna with my USRP N210.
>>
>>
> I used the same setup with the Vert 2450 antennas.
>
> Best,
> Bastian
>
>
>
>>
>>
>>
>> On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl > > wrote:
>>
>> Hi,
>>
>> On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:
>>
>> Hello,
>>
>> How is the timing offset being handled in the 802.11 module. I
>> see that the sync_long block does frequency offset correction
>> and the frame_equalizer block does the phase correction but I
>> dont understand where is the timing offset being handled. Can
>> anyone tell me which algorithm is being used to do that?
>>
>>
>> The Sync Long block correlates the signal with the known pattern of
>> the long preamble to derive how the FFTs have to be aligned in time.
>>
>> Best,
>> Bastian
>>
>>
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Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Bastian Bloessl]

Hi,


On 06/04/2017 04:25 PM, Qurat-Ul-Ann Akbar wrote:
Thank you for the explanation. Can you tell me which antennas did you 
use for your experiments when you wrote your paper? Because I think a 
major problem with my receiver is a very low SNR because everything 
works fine with simulations. Currently I am using Vert 2450 antenna with 
my USRP N210.




I used the same setup with the Vert 2450 antennas.

Best,
Bastian







On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl > wrote:


Hi,

On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:

Hello,

How is the timing offset being handled in the 802.11 module. I
see that the sync_long block does frequency offset correction
and the frame_equalizer block does the phase correction but I
dont understand where is the timing offset being handled. Can
anyone tell me which algorithm is being used to do that?


The Sync Long block correlates the signal with the known pattern of
the long preamble to derive how the FFTs have to be aligned in time.

Best,
Bastian



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Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Qurat-Ul-Ann Akbar]

Thank you for the explanation. Can you tell me which antennas did you use
for your experiments when you wrote your paper? Because I think a major
problem with my receiver is a very low SNR because everything works fine
with simulations. Currently I am using Vert 2450 antenna with my USRP N210.





On Sun, Jun 4, 2017 at 12:33 PM, Bastian Bloessl  wrote:

> Hi,
>
> On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:
>
>> Hello,
>>
>> How is the timing offset being handled in the 802.11 module. I see that
>> the sync_long block does frequency offset correction and the
>> frame_equalizer block does the phase correction but I dont understand where
>> is the timing offset being handled. Can anyone tell me which algorithm is
>> being used to do that?
>>
>
> The Sync Long block correlates the signal with the known pattern of the
> long preamble to derive how the FFTs have to be aligned in time.
>
> Best,
> Bastian
>
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Re: [Discuss-gnuradio] IEEE 802.11 Transceiver Module - Timing offset at receiver side

[Bastian Bloessl]

Hi,

On 6/3/2017 9:11 PM, Qurat-Ul-Ann Akbar wrote:

Hello,

How is the timing offset being handled in the 802.11 module. I see that 
the sync_long block does frequency offset correction and the 
frame_equalizer block does the phase correction but I dont understand 
where is the timing offset being handled. Can anyone tell me which 
algorithm is being used to do that?


The Sync Long block correlates the signal with the known pattern of the 
long preamble to derive how the FFTs have to be aligned in time.


Best,
Bastian

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