WIOO is a "daytimer", broadcasting at full power from local sunrise to local sunset, and at reduced power from local sunset until 45 minutes later (during "critical hours"), after which it signs off to protect clear channel station WMVP in Chicago from skywave interference.
WIOO is a "daytimer", broadcasting at full power from local sunrise to local sunset, and at reduced power until 45 minutes after local sunset (during "critical hours"), after which it signs off to safeguard clear channel station WMVP in Chicago from skywave interference.