Manhole position specification method and manhole position specification system Grant US-11644347-B2 United States of America 09 May 2023
Multilevel pulse position modulation for efficient encoding of information into servo… Grant US-7961424-B2 United States of America 14 Jun 2011
Error correction coding of longitudinal position information Grant US-7787204-B2 United States of America 31 Aug 2010