Abstract
The transmitter identification (Tx-ID) of digital television systems becomes more and more important. Many things need it, such as test and measurement (T&M) equipment and live televised programs. However, identification of the signal source of a weak signal is quite difficult, and therefore the pseudo-random (PN) sequences, widely used in CDMA system, are buried beneath the ATSC signals for the purpose of identification of the emitting transmitter. Kasami sequences are one of well-known PN sequences and are good candidates for transmitter identification since they have good cross-correlation properties and can generate a large number of codes. In the future, there may be an emerging need to categorize Tx-ID sequences. For example, Tx-ID sequences may be grouped separately for different broadcasting companies. In this thesis, we are particularly interested in the Tx-ID sequences made of small set of Kasami sequences. Our main objective is to efficiently categorize and address Kasami sequences. We design a new algorithm that can efficiently classify Kasami sequences within O(n^1.5 (logn)^2)-time, where n is the sequence length. Simulations show that our proposed algorithm is very fast in practice. It will take 0.5 (or 8) seconds on average to find the parameter set (w,d,d') of a 14-bit (or 16-bit) Kasami sequence in the small set, by using a PC with an Intel i7 2.9GHz CPU. We also propose a method of categorization of a PN sequence consisting of several Kasami sequences. If the large length of a PN sequence will be a problem (16-bit Kasami sequence has a length of 65535 bits), we suggest to use two or more Kasami sequences concatenated together to form a single PN sequence. In this case, the size of the first Kasami sequences can be considered as the number of categories of the PN sequences.