It is possible to use your MikroTik Routerboard as a spectrum analyzer. Basic functionality is available without additional software from the CLI (ASCII art) and even more functionality is available after installing the free network tooling called The Dude, also from MikroTik.
Console: Spectral History
Plots spectrogram. Legend and frequency ruler is printed every 24 lines. Numbers in the ruler correspond to the value at their leftmost character position. Power values that fall in different ranges are printed as different colored characters with the same foreground and background color, so it is possible to copy and paste terminal output of this command.
Console: Spectal Scan
Continuously monitor spectral data. This command uses the same data source as ‘spectral-history’, and thus shares many parameters.
The Dude is a free network monitoring and management program by MikroTik.
The Dude network monitor is a new application by MikroTik which can dramatically improve the way you manage your network environment. It will automatically scan all devices within specified subnets, draw and layout a map of your networks, monitor services of your devices and alert you in case some service has problems.
You can download it here.
The Dude has a built-in capability to run graphical Spectral Scan from any of your RouterOS devices with a supported wireless card. Simply select this device in your Dude map, right click and choose Tools -> Spectral Scan.
This will bring up the Spectral Scan GUI with various options and different view modes: