Code Developed in the Lab of Dr. Murat Torlak at University of Texas at Dallas
1. Set up your computer as an Ad-Hoc 802.11b network
- on my Windows 7 Dell, I open the "Network and Sharing Center"
- Click 'Manage Wireless Networks'
- Click 'Add'
- Click 'Create an Ad Hoc Nework'
- Click the 'Save this Network' tick box
2. On my computer it defaults to 802.11g, so I have to force it to 802.11b
- From 'Network and Sharing Center' select 'Adapter Settings'
- Right click the wireless adapter and select 'Properties'
- Click 'Configure' at the top of the 'Wireless Connection Properties' page
- Look for something about Ad Hoc Channel in the 'Advanced' tab (screen shot below)
- for my computer, 0 = b and 1 = g Ad Hoc network. I set it to 0.
3. Begin transmitting beacon signals
- left click on the wireless icon in the start menu bar on the far right
- your Ad-Hoc network should appear in the list of possible networks to connect to
- double click it and you're live! (hovering over it will tell you the status. Its transmitting if it says 'Waiting for Users'
4. Open the VI: USRP wifi demo.vi (inside the Wifi-Demo.llb library)
- Set the IP address and press run
- You should see the SSID's appear in the top center of the VI's front panel
5. How does it work?
A state machine does simple energy detection to detect a Wifi packet coming in between channels 7 and 17 in the 'read' state. When a trigger is found the work is done in the brx.vi inside the connect subVI in the process state of the state machine. Inside brx.vi the flow is, frequency offset correction, (the equalization block isn't really used), and then its demodulated and de-scrambled (according to the spec). The ASCII look-up table takes over and the bits become characters. On the high level block some logic makes sure it's good data before logging it into an array and displaying it on the front panel. Occasionally there are a few characters that are not recognized properly but enabling equalization and adding a few other tuning parameters should minimize these.
Very nice!
Interestingly, the mathworks demoed this SSID decoding at SDR-Boston using USRP + simulink + matlab script (very similar with mathscript node in LV). They also demoed FM radio demodulation on USRP, which we had a year ago.
Wow, it's Great..
If i want to change the standard to 802.11g, what kind of modification should I use?
Thanks
Hi there:
this is really pretty nice but i wonder if there is a similair example to retrieve the payload packets sent over the WiFi as well.
R
Im
Hi,
I am using USRP 2953. When I run this VI accordingly, I am getting 1299 error saying no device found for that particular IP address. But I can find the USRP in NI configuration untility and NI max. Can any one help me out?
Best Regards,
Ramya
Please try using the name RIO0 (not an IP Address since its connected by
cabled PCIe)
Erik
From: Ramya20 <web.community@ni.com>
To: ErikL <erik.luther@ni.com>
Date: 07/07/2015 05:10 AM
Subject: Re: - Decode 802.11b SSID with NI
USRP
Community
Decode 802.11b SSID with NI USRP
new comment by Ramya20 View all comments on this document
Hi,
I am using USRP 2953. When I run this VI accordingly, I am getting 1299
error saying no device found for that particular IP address. But I can
find the USRP in NI configuration untility and NI max. Can any one help me
out?
Best Regards,
Ramya
Reply to this email to respond to Ramya20's comment.
Hi Erik,
It worked. Thankyou.
Ramya
Hello ErikL
Can this example run on a USRP 2901 model ? I only see a difference in the Bandwidth between the two models, so I don´t know if that could affect while running the example. Looking forward for your input.
Regards.