2400/19200 bps 5-CH 13/27MHz FSK receiver
3.3V, single conversion, almost discrete design, no decoding, outputs serial bit-stream (40x90mm).
This receiver is the first part of a transmitter/receiver pair to be developed for a simplex underwater data link. The 2400bps/27MHz receiver/transmitter pair will be a legitimate set for remote control purposes of for instance a model submarine. Currently, the design is being verified and optimised using electronic simulation.
For model submarines, the use of 13MHz often provides an optimal relationship between the size of a submersed antenna outside the hull and RF range. Unfortunate 13MHz RC applications are not allowed in air. Because of this 13MHz radio communication must take place underwater. Radio waves that have their origin underwater may not cross the water to air barrier.
The motivation for this project are "End Of Live" announcements from semiconductor manufacturers. This is what happened to the AX5043, the last transceiver IC suitable for 27MHz. SDR and discrete solutions could be an alternative to the AX5043. The table below provides a rough comparison between different solutions.
SDR IC Discrete
Dimensions Large Small Large
Costs High Low Mid
Functionality Best Good Sufficient
EOL risk High Mid Low