What is the Ch1 in the region served by Central Tablelands?
CREATE TABLE "main_transmitters" (
  "region_served" text,
  "ch_1" text,
  "on_air_date" text,
  "analogue_power" text,
  "digital_power" text,
  "analogue_haat" text,
  "digital_haat" text,
  "transmitter_location" text
);
SELECT "ch_1" FROM "main_transmitters" WHERE "region_served"='central tablelands';