fyp final presentation e1 tapping
TRANSCRIPT
DATA COMMUNICATIONRECOVERY (E1 Tapping)
USMAN TARIQ s470.05M. SHAHZAIB ABBAS s471.05NOMAN MUMTAZ ALI s481.05S.M. ALI ABBAS RIZVI s488.05
A Project in collaboration with Snoopy Devices & Systems
TAPPING
• “Decoding a Communication of any Entity.”• Born with Wars; Concept of Tapping.• Telegraph; Tapping Morse code• Radio; Intercepting Air interface• Telephone; Intercepting any junction point from
Local Loop to Exchange• Optical Fiber taps; Connecting Mirror in series• Ideal taps; Transparent and invisible• Tapping of E-Carrier (E1)
PCM
• “Information present in periodic samples of an Analog Signal represented by digital words in a bit stream”
• Analog to Digital Conversion• High Noise Immunity, Easy Detection.
PCM
• Sampling; Recording Instantaneous values of signals
• Quantization; Assign Discrete amplitudes to each sample
• Coding; Replacing Discrete amplitudes with equivalent Binary codes.
• PCM30/E1; PCM 24/T1
PCM30/E-Carrier (E1)
• 30 users accommodated in one frame using TDM , with one user/timeslot.
• 2 additional time slots used for frame synchronization and signaling.
• 32 time slots with 8 bits each results in 32timeslots*8bits/timeslot=256 bits/frame.
• Each timeslot 64kbits/sec bit rate, resulting in a 2.048 Mbits/s data rate.
• Frame duration = 125microseconds
Tapping of E1• Transmitted E1 frames captured inform of a bit
stream.• Timeslot “0” and Timeslot “16” stripped off
leaving behind payload in 30 timeslots.• Each user assigned its own channel in a separate
file.• Suitable header appended to file of each user to
ensure playing compatibility.• Result = playable user voice in their individual
files/channels.
PROJECT COMPONENTS
MATLAB E1-Simulator
MATLAB E1-Simulator
• MATLAB GUIDE Application.• Works on Matrix manipulation.• Programmed to produce E1-Stream as input
for E1-Tapping Application• Flexible
Building Blocks
• Configuration Block• Audio Recorder• PCM Generator• Graph Plotter• E1 Generator
Configuration Block
• Accommodation of 30 users.• Assignment of unique id’s to each user.• Storing user data in a “flat file” database.
Audio Recorder
• Built-in function.• Takes input on the basis of
3 parameters (Sampling Rate = 8000samples/sec, no of bits/sample = 8 bits/sample, no of channels=1)
• File saved in a Structure.• Structure to Vector/Array
conversion.
PCM Generator
• Same as practical PCM systems used.• Input: 30 Recorded Voice Arrays.• Sampling• Quantization• Coding• Output: PCM Pulse Train; 1s and 0s.
Graph Plotter
• Two Dimensional graph plotting of different forms of 30 input signals.
• Voice Input Signal• Sampled Input Signal• Quantized PAM Signal• 30 Pulse train containing PCM bits.
E1 Generator• Input: Generated PCM
Pulse trains.• Individual byte taken from
each user to make 30 timeslots.
• Appends 2 additional bytes for Synchronization and Signaling.
• Frame Interleaving to form E1 Stream.
• Binary to Decimal conversion to be written in file.
E1-Simulator
C# E1 Tapping Application
C# E1 Tapping Application
• .NET Windows Form Application• Works on different Controls and Methods• Accepts the E1 stream generated by MATLAB
E1 Simulator.• User friendly• Flexible
Work Modules
• Module # 1: Payload Extractor• Module # 2: Channel Allocator• Module # 3: E1 Voice Recovery Unit
Payload extractor
• Calculates Frame Count.• Iterative block used to
remove Ts0/Ts16 (Synchronization/Signaling) Headers from input E1 stream.
• Uses Frame Count as an iterative count for separating headers & payload.
• Displays error message if Frame Count = 0
Header Information
Voice Information
Payload Extractor
Payload
–E1 Frames –Frame Count
Channel Allocator• Receives extracted
payload from Module # 1.• Extracts individual
timeslots from the payload.
• Writes the data of each timeslot in its respective file.
• Displays error message if there is no payload.
Channel Allocator
Extracted Payload
File Writer
Time SlotSeparator
ALL
OC
AT
ION
ALG
OR
ITH
M
Time Slot # 01
Time Slot # 02
Time Slot # 30
File # 01
File # 02
File # 30
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....
E1 Voice Recovery Unit
• Takes individual timeslot data files from module # 2.
• Appends suitable header to each file, converting it in a playable form.
• Plays the files in standard VLC player.
Header Appender E1 Voice Player
File # 01
File # 02
File # 03
File # 30
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VoiceFile # 01
VoiceFile # 02
VoiceFile # 03
VoiceFile # 30
Voice Output
E1 Voice Recovery Unit
E1-Tapping Application
Stream Viewer
Module 1 Module 2
Module 3
E1 StreamE1Frames Payload
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File # 01
File # 02
File # 30
Voice File # 01
Voice File # 02
Voice File # 30
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VoiceOutputs
Headers
Ts
# 0/
Ts
# 16
FrameCount
Count
No. of Frames
Final Design
Simulation and Results
E1-Simulator
E1-Simulator: Audio Recorder
• Small voice amplitudes in 2D graph.
• Voice amplitudes in bordering segment of A-Law Curve.
• Voice: -15 to 20 dB • >0 dB; Noise
E1-Simulator (Sampler)
• Sampling done in accordance with Nyquist criteria.
• Voice frequency range: 300-3400 Hz
• Sampling rate = 8000 samples/s.
E1-Simulator (Quantizer)
• Sampled signal compressed by A-Law, Non Uniform Quantization.
• Less quantization noise.
• Double line effect in 2D graph shows quantized signal.
E1-Simulator (Encoder)
• Assigns 8-bit code to discrete quantized amplitudes.
• Gives PCM Pulse train consisting of 1’s and 0’s as output in 2D graph.
Simulation Results
E1-Tapping Application
E1-Tapping Application (Payload Extractor)
• 3 parameters shown:• Binary Stream• Frame Count• Extracted Payload
(without headers)
E1-Tapping Application (Channel Allocator)
• 30 timeslots in their respective channels shown in output.
• Channels used for writing individual user files.
E1-Tapping Application (E1 Voice Recovery Unit)
• Appends header to each individual file/channel.
• Transparent to the user.
Conclusion
• E1 tapping achieved
E1Stream
Voice I/P Voice O/P