GM Hughes Electronics Corp of the United States expects strong growth in its China-related businesses, from vehicle systems to satellite launches, despite US sanctions restricting sales of high-technology to the mainland. Michael Armstrong, chairman and chief executive of GM Hughes Electronics and Hughes Aircraft Co, said the company was negotiating to build airport control systems for several Chinese airports and was hoping to close a joint-venture car electronics dealsoon. The company is also studying the possibility of a number of other satellite launches with the Chinese even though US sanctions have thrown into question the fate of three launches already contracted. The contracted deals include the Optus 3, being built to replace the Optus B2 - a satellite built by Hughes for Optus Communications of Australia - which was lost in an explosion just after its December 1991 launch by China; and the APT 1 and 2 satellites for Hong Kong's APT Satellite Co, a company led by three Chinese state-owned companies. In August Washington banned sales of sensitive US technology to China in retaliation for alleged Chinese sales of M-11 missiles to Pakistan. Under these sanctions, it is not clear if or when the US Government will give Hughes export licences permitting shipment of the Optus 3 and APT satellites to China. Mr Armstrong said all of Hughes' business with China, worth about US$200 million last year, involved civilian applications. Hughes started dealing with China in 1987, when it worked with the Ministry of Aerospace Industry on the launching of the AsiaSat-I satellite. Its sales to China have included equipment for earth stations, digital telecommunications systems and air traffic control systems. Hughes hoped that within weeks it would be able to conclude negotiations to build a car engine and fuel management control system joint venture in China, Mr Armstrong said. The car market has been hit by the Government's attempts to rein in the economy. Nevertheless, Mr Armstrong said Hughes saw the market as ''very strategic'' and that it remained a key focus for the company in China. Hughes Aircraft is negotiating to build air traffic control systems for 10 Chinese airports. Mr Armstrong said it was premature to reveal any details, but was convinced the Chinese were serious about upgrading the country's more than 300 airports. ''They're spending money,'' he said. The company is keen to supply fixed wireless telephones to China. Mr Armstrong said Hughes' fixed-site cellular communications would enable China to speed up the rate of telephone installation while cutting costs. Hughes is currently creating some 5,000 telephones lines using this technology in the southwestern city of Chengdu. China, where only 0.2 per cent of the population have their own phones, plans to install some 10 million telephone lines a year. But at this rate, Chinese officials have said, it could take as long as four decades before demand for telephone lines was satisfied.