Radio receiver adjacent-channel interference suppression circuit

An adjacent-channel interference detection and suppression circuit for a mobile radio receiver comprising

• a plurality of circuit elements (5, 6 7) defining an intermediate frequency signal path in said receiver;
• means (14.sub.1 -14.sub.N) for adjusting frequency bandwidth in said signal path, including a plurality of filters of differing respective bandwidths, and switching means interposing at least one of said filters in said signal path;
• first means (11) for measuring a first signal level, at an input of said at least one filter;
• second means (11) for measuring a second signal level, at an output of said at least one filter;
• and
• comparison and control means (13), having a pair of inputs, connected to respective outputs of said first and second measuring means, subtracting said second signal level from said first signal level to determine a difference value and, on the basis of said difference value, generating an output control signal which causes said switching means (6) to interpose, in said signal path, one of said filters (14) whose bandwidth is sufficiently narrow to substantially prevent adjacent-channel interference.