According to Chinese media and internet sources, the Luhu-class is mainly used as a technological demonstrator to compare and evaluate different foreign systems, and the two ships initially did not have identical equipment. The first unit had a licensed production of Raytheon AN/SQS-56 sonar, the Italian DE-1164 integrated sonar system, which consists of DE-1160 hull mounted sonar (HMS) and DE-1163 variable depth sonar (VDS), and these were later replaced by domestic copy, SJD-7 sonar system. The second unit had French Thomson-CSF DUBV 23/43 HMS/VDS, which were subsequently replaced by domestic copy SJD-9 sonar system. the combat data systems for the first unit was ZKJ-3 (ZKJ-III), a Chinese equivalent of the Italian IPN-10 combat data system. ZKJ-3 is developed from the export version of IPN-10, SADOC 2, (SADOC = systema dirizione della Operazioni di combattimento). SADOC 2 was sold to China in 1985 and it differs from IPN-10 in that it lacks the data link the latter has. Incorporation of a domestic data link is the main improvement of Chinese ZKJ-3, making it the Chinese equivalent of IPN-10. The combat data system of the second unit is ZKJ-4, which is the Chinese version of French Thomson-CSF TAVITAC combat data system, two of which were sold to China in 1985 and delivered 2–3 years later. These combat data systems were later replaced by more advanced follow-on equipment such as ZKJ-4A/B series during upgrades. Experience gained in handling these foreign systems has helped subsequent development of similar Chinese systems.