At what frequency does Secondary Surveillance Radar (SSR) interrogate?

Secondary Surveillance Radar (SSR) operates primarily at a frequency of 1030 MHz for interrogations. This frequency is specifically designated for the SSR's uplink signal which is sent from the radar system to the aircraft's transponder to elicit a response. The use of 1030 MHz facilitates effective communication and ensures the radar system can accurately receive responses from transponders, which typically operate on a secondary frequency of 1090 MHz to transmit identification and altitude data back to the radar.

Understanding the significance of the 1030 MHz frequency is crucial, as it plays an essential role in the functionality of SSR systems, enhancing air traffic control and surveillance capabilities in a crowded airspace. The other frequencies listed are either associated with different radar systems or are not used for SSR interrogations.