2

important milestones in the development of spread spectrum communications came from a patent

filed in mid 1941 by Hedy Lamarr and George Antheil. Hedy, who move to the United States

from Austria and later became a well-known movie star, help George developed a method for

controlling a torpedo that implemented a frequency-hopping guidance system. The transmitter

carrier would change frequency according to a randomized non-repeating code [2]. In 1948, the

# U.S. mathematician Claude Shannon published a Mathematical Theory of Communication as a

monograph in the Bell System Technical. This paper is remarkable because of its elegant

theorems, derived from statistical characterizations of both the information source and the

channel effects [3]. This includes the theorem for perhaps which he is most well known, the

communication capacity of the band-limited additive Gaussian noise channel. His theorem is:

(1)

= ∗

_{2 }

1+

/

where the W is the channel bandwidth in Hz, S is the signal power in watts, and N is the total

noise power of the channel in Watts [4].

# One of the early adoptions of direct sequences occurred for the purpose of ranging for

the tracking-range radar systems at the Jet Propulsion Laboratory (JPL) for use in the Corporal

guidance system link. Frank Lehan of JPL noted that radar signal correlation function was of

prime importance in determining the accuracy of the range estimate. The pseudo-noise codes

(sometime called m-sequence) were investigated starting around the 1950‟s. Also in the 1950‟s,