H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
H04B1/06—Receivers
H04B1/16—Circuits
H04B1/26—Circuits for superheterodyne receivers
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations