Circuit and method for detecting frequency correction burst in TDMA digital mobile communication system

#This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. .sctn.119 from an application for CIRCUIT AND METHOD FOR DETECTING FREQUENCY CORRECTION BURST IN TDMA DIGITAL MOBILE COMMUNICATION SYSTEM earlier filed in the Korean Industrial Property Office on the 24.sup.th of Aug. 1996, and there duly assigned Ser. No. 35462/1996, a copy of which application is annexed hereto.

#1. Technical Field

#The present invention relates to a time division multiple access (TDMA) digital mobile communication system, and more particularly, to a circuit in a mobile station for detecting a frequency correction burst, which is periodically transmitted from a base station to achieve frequency adjustment and time slot synchronization between the base station and the mobile station in the TDMA digital mobile communication system.

#The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example.

#A more complete appreciation of the present invention, and many of the attendant advantages thereof, will become readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:

#FIG. 1 illustrates a contemporary circuit for detecting a frequency correction burst in a TDMA digital mobile communication system;

#Referring now to the drawings and particularly to FIG. 1, which illustrates a contemporary circuit for detecting a frequency correction burst signal in order to adjust the frequency synchronization between a fixed base station and a mobile station in a TDMA communication system. As shown in FIG. 1, the circuit includes an adaptive band-pass filter 10 coupled to process one of the two baseband Quadrature signals, the I and Q channel signal sampled at one sample per bit time from a receiver (not shown) of a mobile station (i.e., radiotelephone), a pole adaptation block 12, a first energy estimation block Yn14, a second energy estimation block Xn16, a gain adaptation block 18, a tone detection block 20, and a timer 22.

#Adaptive band-pass filter 10 filters one of the I and Q channel signals modulated by continuous phase shift key of a baseband in order to produce a band-filtered signal Yn which is produced to the pole adaptation block 12 and the first energy estimation block 14. The signal output from the adaptive band-pass filter 10 is labeled Yn. The filtered signal is given in equation (1). Both the gain and the pole of this filter are adaptive. The pole of the filter 10 is moved so that the pass-band of the filter 10 encompasses the received signal. An instantaneous frequency of the band-filtered signal is estimated in the energy estimation block 14, and then is fed back to a gain adaptation block 18 to the adaptive band-pass filter 10.

#y.sub.n+1 =b.sub.n x.sub.n+1 +a.sub.n y.sub.n +(-ro.sup.2)y.sub.n-1(1)