What modulation is APRS?

Excuse me, could you please clarify what you mean by "APRS" in the context of modulation? Is this a specific technology or acronym that you're referring to? If so, it's not immediately clear to me which technology you're inquiring about. In the world of cryptocurrency and finance, modulation is not a commonly used term related to our field. However, if you're asking about modulation in the broader context of telecommunications or signal processing, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. Assuming "APRS" might be a typo or abbreviation for something specific in the telecommunications realm, such as a specific type of wireless technology, I would need more context to provide an accurate answer. Could you please elaborate on the technology or acronym you're referring to, and how it relates to modulation? This would help me give you a more precise response.