What does the number after the RSSI mean on my OSD?

https://preview.redd.it/selmcj0tcpyf1.png?width=1185&format=png&auto=webp&s=d5a62c5f490bd4310565e353dc7d77e043301fcd

hey everyone,

I’m trying to understand what the number after the RSSI means in my OSD (see image).

During flight, my OSD shows something like “-84 : 2”, but sometimes that “2” changes to “1”.

Here’s my setup:

• Radio: Radiomaster TX12, set to X100 protocol
• Receiver: Radiomaster XR4
• RX antennas: one original XR4 antenna mounted horizontally at the front of the drone, and one GEPRC triband stick antenna mounted vertically at the rear

I’d like to know exactly what that number represents. Is it related to antenna diversity, packet rate, or something else?

Thanks in advance for any help!