FM modulator output control during turn on

Details FM modulator output control during turn on FM modulator output control during turn on

2006-09-12

2006-09-12

Vo, Nguyen T. (Department: 2618)

Telecommunications

Transmitter

Noise or interference elimination

C455S119000, C381S007000

Reexamination Certificate

active

07107024

ABSTRACT:
The present invention provides a system and a method to prevent undesired sounds during FM modulator turn on. The system includes an RF attenuator circuit, a delay switch circuit, an RF ramp up circuit, and audio ramp up circuit. The RF attenuator circuit significantly reduces the RF signal from the FM modulator when the FM modulator is initially turned on, which significantly reduce whistle caused by the RF signal from the modulator beating with the local oscillator in the radio receiver. After allowing time for the PLL to lock onto the RF signal, the time delay switch circuit becomes active and charges the RF ramp up circuit. The RF ramp up circuit gradually increases the RF signal by gradually deactivating the RF attenuator circuit. The gradual increase of the RF signal is slower than the response time of the radio AGC, thereby preventing any pop as the RF signal is provided to the radio receiver.

REFERENCES:
patent: 4140960 (1979-02-01), Ohsawa
patent: 4600947 (1986-07-01), Chamberlain et al.
patent: 4991212 (1991-02-01), Foti
patent: 5204904 (1993-04-01), Carver et al.
patent: 5255094 (1993-10-01), Yong et al.
patent: 5422955 (1995-06-01), Guzman et al.
patent: 5642076 (1997-06-01), Naokawa et al.
patent: 5969561 (1999-10-01), McGillan
patent: 6075412 (2000-06-01), Bainvoll
patent: 6163711 (2000-12-01), Juntunen et al.
patent: 6324385 (2001-11-01), Nagano et al.
patent: 6346854 (2002-02-01), Heithoff
patent: 6445732 (2002-09-01), Beamish et al.
patent: 6448857 (2002-09-01), Quintanar et al.
patent: 2003/0012389 (2003-01-01), Brice et al.
patent: 58075332 (1983-05-01), None
patent: 2000013253 (2000-01-01), None
patent: 2000013253 (2000-01-01), None

Affiliated with

Also associated with

Rating

FM modulator output control during turn on does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with FM modulator output control during turn on, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and FM modulator output control during turn on will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3535737