Adding to DuMont's troubles was the FCC's 1948 "freeze" on television license applications. This was done to sort out the thousands of applications that had come streaming in, but also to rethink the allocation and technical standards laid down prior to World War II. It became clear soon after the war that 12 channels ("channel 1" had been removed from television broadcasting use because storms and other types of interference could severely affect the quality of its signals) were not nearly enough for national television service. What was to be a six-month freeze lasted until 1952, when the FCC opened the UHF spectrum. The FCC, however, did not require television manufacturers to include UHF capability. In order to see UHF stations, most people had to buy expensive converters. Even then, the picture quality was marginal at best . Tied to this was a decision to restrict VHF allocations in medium- and smaller-sized markets. Meanwhile, television sets would not be "required" to have all-channel tuning until 1964, with the passage of the All-Channel Receiver Act.