Lowrance has made sonar electronics for fishermen and recreational boaters since 1957. Sonar or 'SOund', 'NAvigation' and 'Ranging' technology was developed during WWII. Lowrance manufactures high-definition, full-sized, compact and portable Sonar units, also called depth finders and fish finders. The company also has a model that is designed exclusively for the needs of ice fishermen. But regardless of model, Lowrance provides standard troubleshooting guidelines for owners to fix minor problems.