Television – Monitoring – testing – or measuring – Transmission path testing
Patent
1999-01-22
2000-09-12
Peng, John K.
Television
Monitoring, testing, or measuring
Transmission path testing
348192, 348180, 348181, 348193, 348194, 714704, 714707, 375260, 375261, 375224, 375225, 375295, 375298, 359132, 359110, 359191, 359192, 359125, 359158, H04N 1700, H04B 1700, H04K 110, H04L 2302, H04J 1402
Patent
active
061184799
ABSTRACT:
In FIG. 5, a plurality of signal sources 21.sub.1 to 21.sub.N each generate a carrier with different frequencies. A pulse signal generating portion 23 generates a pulse signal with the same period and time width as those of a horizontal synchronizing signal in NTSC system color television broadcasting. Delay devices 32.sub.1 to 32.sub.N delay timing of the pulse signal for a randomly predetermined delay amount. Level adjuster 52.sub.1 to 52.sub.N generate a modulating signal by adjusting each pulse base of the delayed pulse signal for a level within a range between 12.5% and 74.375% with respect to a pulse top. Modulators 42.sub.1 to 42.sub.N output a signal obtained by modulating the carrier with the modulating signal. A multiplex portion 24 multiplexes the modulated signals to output a resultant signal as a test signal. The error rate of a QAM signal is evaluated with the test signal. It is therefore possible to evaluate the error rate of the QAM signal in a signal state approximate at the maximum to a state of an actual AM video signal (that is, analogous distribution characteristics of the multiplex signal amplitude). In the error rate evaluation method according to an embodiment of the present invention, it is thus possible to accurately evaluate the error rate of the QAM signal under the strictest conditions, which may occur in the actual, AM video signal, thereby ensuring the reliability of the entire CATV system.
REFERENCES:
patent: 4278850 (1981-07-01), Sato et al.
patent: 4941208 (1990-07-01), Olshansky et al.
patent: 4989200 (1991-01-01), Olshansky et al.
patent: 5134509 (1992-07-01), Olshansky et al.
patent: 5208666 (1993-05-01), Elkind et al.
patent: 5293260 (1994-03-01), Kikawa et al.
patent: 5451999 (1995-09-01), Wesolowski
patent: 5874992 (1999-02-01), Caporizzo
patent: 6043919 (2000-03-01), Yoshizawa
"QAM Transmission Performance in AM/QAM Hybrid SCM Optical Transmission System" by Maeda et al., 1991 Television Society, pp. 473-474.
"Analysis of BER of 16 QAM signal in AM/16 QAM hybrid transmission system" by K. Maeda et al., Electron Letters, vol. 29.
"Broad-Band AM-VSB/64QAM Cable TV System over Hybrid Figer/Coax Network" by X. Lu et al., IEEE Photonics Technology Letters, vol. 7, No. 4, 1995.
"The Effect of Analog Video Modulation on Laser Clipping Noise in Optical Video-Distribution Newtworks" by Stuart S. Wagner et al.
"Color Television", edited by Nihon Hoso Kyokai, P. 570.
"Introduction to Cable Television, basic to application" supervised by Takehiro Izumi, Corona Publishing Co., Ltd. P. 196.
Maeda Kazuki
Morikura Susumu
Utsumi Kuniaki
Matsushita Electric - Industrial Co., Ltd.
Natnael Paulos
Peng John K.
LandOfFree
Optical transmission method, error rate evaluation method applie does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical transmission method, error rate evaluation method applie, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical transmission method, error rate evaluation method applie will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-100360