摘要:
An AFC control apparatus in mobile communication equipment includes a depreading unit, first integrator, and control section. A despreading section despreads the reception signal. The first integrator integrates despread outputs obtained by despreading, of pilot symbols contained in a pilot channel of the reception signal, N (N is a number of 2 or more) consecutive first symbols and N second symbols succeeding the N first symbols, and generates first and second integral outputs. The control section detects any phase shift amount between the first and second integral outputs and controls the frequency of the local signal in accordance with the detected phase shift amount. An AFC control method and mobile communication equipment having the above apparatus and method are also disclosed.
摘要:
Le procédé évalue un écart entre une fréquence de modulation, combinée à un premier signal en bande de base pour former un signal émis et une fréquence employée par le récepteur pour former un second signal en bande de base à partir d'un signal reçu, afin d'ajuster la fréquence employée par le récepteur. Connaissant un segment temporel du premier signal et la position temporelle d'un segment correspondant du second signal, les segments comprenant N échantillons à une fréquence d'échantillonnage F e , on calcule une transformée en fréquence Y(f), de taille N, du produit du complexe conjugué dudit segment du premier signal par le segment correspondant du second signal, et on évalue l'écart de fréquence Δf qui rend la transformée en fréquence Y(f) la plus proche de C.S c (f-Δf), où S c (f) = 1-exp(-2jπNf/F e ) 1-exp(-2jπf/F e ) , et C est un coefficient complexe.
摘要:
The present invention relates to an improved demodulator for locking onto and tracking a carrier. Harmonic frequencies are occasionally generated by demodulation circuitry. When this occurs, the harmonic frequencies can interfere with the demodulator's locking and tracking functions, especially if the harmonic frequencies are near a down converted carrier's frequency. A system and method are disclosed which provides an offset to a frequency synthesizer (107) whose output frequency (F1, F2) is used to down convert (104) the carrier. The offset alters the frequency of the down converted carrier so as to shift it away from the interfering harmonics. In this regard, the demodulator is enabled to lock onto and track a carrier when previously not possible.
摘要:
In a communication system using the time diversity transmission scheme, the communication system provided with the stable automatic frequency control circuit with the wide frequency pull-in range and under low CN ratio transmission is achieved by removing the modulation phase from the received data through the application of the data correlation of the time diversity. The frequency offset in the received signal is compensated as the phase rotator rotates the phase of the received signal, the phase converter converts the phase rotator output into a phase, the serial-to-parallel converter converts the phase converter outputs into serial-to-parallel sequence, the delay units gives a delay to the serial-to-parallel converter output, the phase adder adds the serial-to-parallel converter output to the delay unit output, the multiplier multiplies the phase adder output by a certain value, the integrator integrates the multiplier output, another integrator integrates the integrator output, and the phase rotator controls the phase of the received signal based on the other integrator output.
摘要:
Ein Verfahren, das ohne besonderen Hardwareaufwand für die Synchronisierung der Trägerfrequenzen zwischen der Basisstation und den Teilnehmerstationen auskommt, besteht darin, daß alle Empfangs- und alle Sendeträgerfrequenzen der Basisstation von einer gemeinsamen Referenzfrequenz (ZFLOBS) abgeleitet werden und daß jeweils ein von einer Teilnehmerstation ausgesendeter Sendeträger mit der korrespondierenden Empfangsträgerfrequenz in der Basisstation verglichen wird. Eine daraus ermittelte Frequenzablage wird der Teilnehmerstation mitgeteilt und die Sendeträgerfrequenz dieser Teilnehmerstation so eingestellt, daß die Frequenzablage minimal wird.
摘要:
A method and apparatus for controlling frequency of a multi-channel transmitter. A reference frequency is generated and emitted to a thermally stable frequency discriminator. The thermally stable frequency discriminator emits a dc voltage to a plurality of individual oscillators. The individual oscillators in continuous wave mode or modulated by baseband signals are combined into a multi-channel signal at an intermediate range of frequencies. The multi-channel intermediate range of frequencies is preferably amplified and emitted as an output signal. At relatively lower frequencies, such as 4-6 GHz, up-conversion of the output signal is not necessary. At relatively higher frequencies, an up-converter can be used to employ a second thermally stable frequency discriminator.