This White Paper focuses on how the mud-pulse telemetry transmitter sends out blocks of encoded pulses after every flow cycle in the following order:
Inside the Advanced Mud Pulse Telemetry: M-Ary Encoding for MWD Tools (Chapter 2) White Paper you will find all about:
- Synch blocks.
- Survey sequence number blocks.
- Toolface/Logging Sequence Number Blocks.
- Data Block Formats.
- Breaking Binary Data into 2 and 3-bit packets.
- M-Ary Pulse Encoding (including examples).
About M-Ary Pulse Encoding
M-Ary pulse encoding is a form of phase shift keying. The packets are encoded in 4 TU’s (for 2-bit) or 8 TU’s (for a 3-bit packet). The position of the rising edge of the pulse determines the packet value.
For instance, in a 2-bit packet, the pulse would start at position 0 TU when the packet value is 3, at 1 TU for a value of 2, at 2 TU for a value of 1 and at 3 TU for a value of 0. Note that the pulse width itself is 2 TUs. Each packet is separated from the next packet by 4 TU’s.
Here's an example: