Fast transmissions are limited to a maximum range of 300 cm (10 ft), with the bit error rate being 2-4%. Medium-speed transmissions increase the distance to 450 cm (15 ft) for the same error rate. Finally, slow transmissions with nearly zero error rates can work reliably over distances of up to 7 meters (23 ft).
Fast = 1000bps, medium = 500bps, slow = 100bps