Pulse or digital communications – Repeaters – Testing
Patent
1990-12-21
1993-06-15
Safourek, Benedict V.
Pulse or digital communications
Repeaters
Testing
375 97, 375113, H04B 701, H04L 706
Patent
active
052205843
ABSTRACT:
A multiple tone signal is demodulated and synchronization is obtained by precisely locating frame boundaries in order to ensure reliable communication in the presence of anomalies such as Doppler shift, multipath propagation, and additive electronic noise. One such signal, TADIL-A or Link-11, employs multiple tone audio waveforms that are used to modulate RF carriers for the transmission of digital data. Initially, the signal is frequency divided and classified to determine if the incoming frame is a preamble, data or noise. For preamble frames, a digital filter is used to extract the 605 Hz tone in the time domain, and the resulting real-valued signal is passed through a first Hilbert transform to generate the corresponding imaginary complex-valued signal. Unfiltered data frames are passed through a second Hilbert transform and the output is multiplied by the complex conjugate of the stored Doppler reference signal to produce a Link-11 Signal stripped of Doppler. As a result of the demodulation process, the entire waveform now includes frequencies separated by an integer multiple of 110 Hz. Therefore, the composite waveform has a period of 9.09 milliseconds. The composite waveform partially repeats itself at least once in each 13.33 msec frame interval. Using this property, it is possible to determine the location at which the composite signal becomes discontinuous and thereby locate the synchronization frame boundaries.
REFERENCES:
patent: 2849605 (1958-08-01), Fickett et al.
patent: 3593256 (1971-07-01), Gannon
patent: 3842399 (1974-10-01), Kneuer et al.
patent: 4076956 (1978-02-01), Dogliotti
patent: 4199809 (1980-04-01), Pasahow
patent: 4276650 (1981-06-01), deJager et al.
patent: 4493093 (1985-01-01), Veillard
patent: 4627080 (1986-12-01), Debus, Jr.
patent: 4707839 (1987-11-01), Andren et al.
patent: 4719468 (1988-01-01), Jehle et al.
patent: 4875050 (1989-10-01), Rathi
patent: 4876546 (1989-10-01), Koerner
Military Standard, Mil-Std-188-203-1A entitled Interoperability and Performance Standards for Tactical Digital Information Link (TADIL)A, Jan. 8, 1988, U.S. Department of Defense.
Mikros Systems Corp.
Safourek Benedict V.
LandOfFree
System for demodulation and synchronizing multiple tone waveform does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for demodulation and synchronizing multiple tone waveform, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for demodulation and synchronizing multiple tone waveform will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1048664