62 results about "Sync word" patented technology

In RF transceivers, a method and system for using phase shift key (PSK) sync word for fine tuning frequency adjustment are provided. One aspect of the invention provides for adjusting a local oscillator frequency in a radio frequency (RF) receiver when a residual DC offset remains after a coarse frequency offset adjustment if performed. The fine adjustment may be necessary because of the synchronization required with a PSK-based modulated portion of a Bluetooth packet. A residual phase shift detected in a sync sequence portion of the Bluetooth packet may be utilized to determine a residual or fine frequency adjustment. This approach may allow an RF receiver to operate, in some instances, without the need for an equalizer. In this regard, the power consumed by the RF receiver may be minimized and / or the overall cost of the RF receiver may be reduced.

Provided is a frame synchronization method for synchronizing frames with pilot blocks added thereto based on differential correlation information in a satellite communication system. The method can acquire a highly reliable frame synchronization estimation value by achieving a multi-step threshold value test using pilot blocks after a correlation analysis and a threshold test based on a sync signal in order to resolve the problem of a low signal-to-noise ratio and a large frequency error and acquire highly reliable frame synchronization performance, and can overcome distortion of a correlation analysis value caused by the frequency error by analyzing correlation based on differential information. The method includes the steps of: a) performing correlation analysis and a threshold test by using a sync word; and b) performing a multi-step correlation value test by using the pilot blocks added to the frames prior to the sync word.

Methods and apparatus for detecting L-bit sync words occurring at N-bit intervals in PPM-encoded servo pattern read signals read in magnetic tape drives. A soft output detector processes the PPM-encoded servo pattern read signal to produce a series of soft output samples corresponding to respective bits encoded in the servo pattern. A sync word detector then produces block correlation values for respective positions of a sliding L-sample block in the series of soft output samples by (i) calculating at each block position bit correlation values indicating correlation between respective samples and corresponding bits of the sync word and (ii) summing each bit correlation value minus a predetermined function of the corresponding sample value. The sync word detector then detects a sync word at the block position with the maximum block correlation value in an (N+L−1)-sample sequence of the series of soft output samples.

The invention disclose an adaptive equalizing device and method, in which a correlation between a received signal and a sync word signal is calculated. A window signal having a time span which is equal to an equalization range for an adaptive equalizer is defined. A power sum of the correlation output signal in each of window signals #1, #2, #3, ... are calculated by sequentially shifting the window signal in the time domain, and a rising edge of the particular window signal whose power sum maximum defines a symbol sync timing.

The portion of TDMA frames otherwise containing the sync word is eliminated for one or more data frames at the end of a TDMA data burst to provided added bandwidth for data payload or for a reduced bandwidth. Once a communication channel has been established and is in steady state mode (after receipt of one or more frames), the sync word is eliminated from the remaining frame structure. Drift of a local clock with respect to an incoming data stream is monitored using an oversampled or multiplied master clock to provide suitable resolution to determine an approximate position of an active edge of the master clock with respect to a bit or symbol being clocked. Any drift from center results in an adjustment of the local master clock. In a preferred embodiment, the drift is measured in a last bit or symbol of a received TDMA burst, and the master clock is adjusted to re-center the local master clock with respect to that last bit. Accordingly, the receiver is ‘tuned’ to the clock signal of the transmitting TDMA device such that the receiving TDMA device can predict where the next start of frame will occur. By doing so, the sync word is no longer necessary in the remaining frames of the TDMA burst to decode the start of next TDMA frame. The sync word may be included in more than one frames in the beginning of the TDMA burst, but is eliminated from one or more frames at the end of the TDMA burst.

Both a pre-word (PW) and a sync word (SW) are used to establish a synchronization or only the sync word (SW) is used to establish a synchronization in accordance with an operational status related to the synchronization in a mobile wireless communication apparatus. For example, during an initial synchronization with a control channel (110) being received, both the pre-word (PW) and the sync word (SW) are used to establish a synchronization when a calculation result in a synchronization calculating part exceeds a predetermined threshold value only once. During an initial synchronization with a direct communication channel (112) being received, both the pre-word (PW) and the sync word (SW) are used to establish a synchronization when the calculation result exceeds the predetermined threshold value once; or alternatively, only the sync word (SW) is used to establish a synchronization when the calculation result successively exceeds the predetermined threshold value twice. According to the present invention, the sync word is shortened so as to quickly establish a communication link, and the sync detection can be performed with high precision.