Telecommunications – Transmitter – Frequency conversion
Patent
1997-11-07
1999-12-14
Chin, Wellington
Telecommunications
Transmitter
Frequency conversion
332145, H04B 138
Patent
active
060029234
ABSTRACT:
A transmitter subsystem is disclosed whereby the output frequency spectrum of a DDS device, for use in the transmitter subsystem, is frequency multiplied to achieve greater frequency coverage at the RF bands. In one embodiment of the present invention, a DDS device is structured in such a way that the DDS output signal spectra can be multiplied directly for direct conversion to RF or IF bands. As such, the requirements placed on the DACs in the DDS device are lessened, because the DACs require much lower sampling frequencies than those used in the existing technology. Also, the requirements placed on the implemented bandpass filters used for image rejection in the applied upconverters are lessened, because of the larger frequency difference created between the desired output and the image frequency band. In a second embodiment of the present invention, a DDS device is also structured in such a way that multiplication of the baseband spectra can be accomplished at the IF. Consequently, in accordance with the present invention, less complex or costly DACs can be used for generating wideband signals at higher frequencies, but relatively high linearity signals can still be attained.
REFERENCES:
patent: 5128623 (1992-07-01), Gilmore
patent: 5309479 (1994-05-01), Cheah
patent: 5329260 (1994-07-01), Poplin
patent: 5374903 (1994-12-01), Blanton
patent: 5430416 (1995-07-01), Black et al.
patent: 5463357 (1995-10-01), Hobden
patent: 5519732 (1996-05-01), Chester
patent: 5521946 (1996-05-01), Main
patent: 5649297 (1997-07-01), Park
patent: 5668505 (1997-09-01), Vu et al.
patent: 5757854 (1998-05-01), Hunsinger et al.
patent: 5796783 (1998-08-01), Crawford
L.O. Eber, et al., "Digital Generation of Wideband LFM Waveforms," International Radar Conference (Apr. 1975): 170-175.
B.V. Kameke, "Synchronisierte Mikrowelenoszillator als Leistungverstarker und Frequenzteiler in Brietband-Richtfunksystemen," 70 (Apr. 1980): 243-249.
Chin Wellington
Telefonaktiebolaget LM Ericsson
Tran Dablo N.
LandOfFree
Signal generation in a communications transmitter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Signal generation in a communications transmitter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Signal generation in a communications transmitter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-872628