0
\$\begingroup\$

I was wondering what energy efficient protocol should I use for a FSK modulation in a steel conductor. My limitation is on the number of continuous bits I can transmit due to the charging and discharging of the capacitor, and the circuit is battery operated. From my testing I can only transmit a byte at a time with a delay of 200us before a transmission of the next byte.

For a byte communication, the protocol I was considering is to use start, data bits and send it in byte chunks. The packet is going to be fixed length to reduce the packet size. I am not very sure would I need preambles and a stop bit as that would increase the data size, and the start bits and fixed length would determine the start and end of the data transmission.

Paul

\$\endgroup\$
1
\$\begingroup\$

This is where formats such as Manchester encoding come in to play. With Manchester encoding, the data is encoded into the transitions and not the levels. Equal numbers of 1s and 0s are always sent, so there is no issue with capacitance getting charged up with a bias of 1s or 0s. Also, clock recovery is simpler since the clock is embedded with the data.

\$\endgroup\$
  • \$\begingroup\$ I have actually implemented it using Manchester encoding and added error correction, and plus sending it in burst due to capacitor charge/discharge. This works reliably well over a 2km range. \$\endgroup\$ – user468662 Nov 2 '15 at 12:13
0
\$\begingroup\$

Look at the common UART ("RS232") serial protocol. It handles a byte at a time, and can be sent at a wide range of bit rates, provided the sender and receiver agree on the bit rate.

The UART protocol uses one start bit, 5 to 8 data bits, and a stop bit. The stop bit merely returns the line to the idle state.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.