LA3370

No.619-3/11

SNC (stereo noise control) and HCC (high-cut control)

The LA3370 has SNC and HCC terminals for improved S/N ratios when operating in weak radio fields. By adjusting

the SNC terminal, noises unique to stereo FM in weak fields can be reduced. The HCC terminals permits further

improvement of effective S/N ratios by lowering treble levels of FM noises in weak fields. (See Fig.2)

STEREO deteriorates approximately 21.7dB (compared to MONO) in weak radio fields (Fig.2). Generally, when

S/N ratios deteriorate below 30 to 40dB, noises become quite noticeable. Section (1) shows ways to set SNC and

HCC when radio field strengths are divided into 3 regions, A, B, and C (Fig.2). SNC is expected to function in region

A, and HCC in region B. In region C, shallow muting is effected in the IF stage.

Sample Application Circuit and Equivalent Circuit Block Diagram