Summary

This is a complete design for a system to send and receiver data using ultrasonics. Besides being a useful system for sending data it is also intended as a platform for exploring concepts and firmware as used in software defined radio (SDR) but without the complexity of RF and FPGAs.
Included is the full design package for the electronics (schematic, PCB design files, parts lists, etc.) along with stl files for the parabolic tower. There is also a set of notes for more info on constructing the PCB and notes on the firmware.
See more in the article in EDN at: https://www.edn.com/exploring-software-defined-radio-without-the-annoying-rf-part-1/
and: https://www.edn.com/exploring-software-defined-radio-without-the-annoying-rf-part-2/

The PCB holder seen in the picture can be found at: https://www.thingiverse.com/thing:5691258

Post-Printing

To assemble the parabolic tower

            The parabolic tower includes 4 parts: 2 pieces for the parabolic disc, the tower, and the base.  First glue the 2 halves of the parabolic dish together. Next connect the tower to the base using a 1/4" nut inserted into the back bottom of the tower.  Then the 1/4" x 3/4" bolt is inserted into the bottom of the base then the base, with the bolt, are connected together and the bolt tightened. The ultrasonic receiver transducer is hot glued to the curved holder extending from the parabolic dish. Make sure that the front of the transducer faces the parabolic dish. The ultrasonic transmitter transducer is then hot glued to the curved holder on the tower (below the receiver transducer) . Make sure it is facing out (away from the tower. Note in the tower there are 2 holes in the tower you can use as a sight to aim the parabolic dish.

sdr

ultrasonic