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Video transmission using USRP

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Presentation on theme: "Video transmission using USRP"— Presentation transcript:

1 Video transmission using USRP
By Asha Iype Shashanka CD 12/07/2011

2 Introduction Mobile multimedia communications
USRP as a platform to excavate mobile computing environments Simple DVB setup Webcam on the air using USRP Modulation in software using GNU Radio

3 Basic block diagram Video file source (webcam or a video file)
GNU Radio modulator and processing USRP transmitter File sink (video playback e.g., VLC player) USRP receiver GNU Radio demodulator and processing

4 Video Transmitter GNU Radio

5 Real time video streaming
Why do we need VLC streaming? How do we link webcam and GNU radio?

6 Real time video streaming
A webcam is one of the simplest of camera designs, containing no video encoder onboard VLC streamer for encoding and streaming The stream output feature in VLC outputs the stream read by the VLC to a file

7 Real time video streaming
A UNIX "pipe" : what's written at one end shows up as available data at the other end Create the pipe using the command “mkfifo <filename>”

8 GNU Radio Transmitter Multiply Constant File Source Packet Encoder

9 GNU Radio Transmitter Flow Diagram

10 USRP Transmitter RF Transceiver USB FPGA DAC USB2 interface to PC
Digital up conversion Interpolation High Speed 14-bit DA DAC Clock - 128MS/s RFx2400 RFX2400 has a band-pass filter around the 2400 to 2483 MHz

11 Video receiver USRP GNU Radio VLC player

12 USRP receiver RF front-end 2.412 GHz ADC FPGA USB RFX2400
….bit stream RF front-end ADC FPGA USB 12bit High Speed AD - 64MSamples/s -Downconversion -High-BW math -Reduce data rate -Cypress FX2 - For PC interface RFX2400

13 GNU Radio USRP source Low-pass filter GMSK demodulator Packet decoder
File sink

14 GNU Radio flow diagram

15 Real-time streaming using VLC player
Receiving pipe just gets the input stream at one end and delivers to the other end Create the receiving pipe “mkfifo rx.ts” Transcoding – MPEG2 + MPGA (TS) ‘Display locally’ option Start streaming UNIX pipe

16 Project activities Simulation without USRPs Transmission with USRPs
Stored video file and loop back Transmission with USRPs Stored video file with USRP Real time video transmission Streaming with USRP

17 Results and Observations
Received signal FFT plot with USRPs 3 meter apart Received signal FFT plot with USRPs >9 meter apart

18 Results and Observations
Delay in reception of the video Delay with large distance (>9m) between USRPs Delay with short distances (1m) between USRPs Delay with stored video file Delay is mainly because of streaming and processing (encoding and multiplexing)

19 Results and Observations
Packet loss at reception of the video Negligible packet loss at short distances (1-3m) Distortion in video received at large distances (>9m) showing more packet loss Distortion was extremely high with increased distances and with interferences like wall and furniture Power received is inversely proportional to square of the distance

20 Results and Observations
Distortion observed at large distances

21 Results and Observations
FFT plot fluctuation at the receiver showing packet loss uUuUuU ( USRP Underrun) at the transmitter The speed of the computer processor plays a role

22 Future work Try with different player and different codec for faster and better encoding Different modulation schemes suitable for video transmission Implementing good error correcting schemes to correct the video frames received and hence reduce distortion

23 Demonstration

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