Command Reception in Water

We put a self-propelled ball in a latex glove and attach ISL A3030C No6.1 to the outside. We place the combination in a tub of water and let the ball propel the ISL around the tub, immersed in water most of the time. We place the tub in an FE2A faraday enclosure.



Figure: ISL A3030C No6.1 Moving in Water.

We have only one BNC feedthrough in this enclosure. We use this feedthrough for the data reception antenna, which we connect to one input of an Octal Data Receiver. We must open a hole in the enclosure wall to allow the command antenna cable to enter. This compromises the isolation of our enclosure. We add two more antennas by raising the lid a little, but this does not help much. The result is 92% reception of data messages transmitted by the ISL.

We use the ISL Controller Tool to request acknowledgments from the ISL in response to commands transmitted by our 915-MHz Command Transmitter (A3029B). Each acknowledgement is a single 915-MHz message transmitted by the ISL and received with 92% probability by the Data Receiver. We request 116 acknowledgements and receive 100. These observations suggest the reception of 915-MHz commands by the ISL's crystal radio while swimming in water is roughly 94%.