SRRC Filing Timelines for a Product Entering China
SRRC radio type approval in China takes 8 to 16 weeks, requiring local agent representation, strict customs sample clearing, and accredited domestic lab scans.
Power Spectral Density Cap
Meaning
Strict upper boundaries for the signal power allowed within a narrow slice of frequency ensure that transmitters do not overwhelm the medium. A power spectral density cap sets the maximum intensity of the signal when measured in increments such as one megahertz or three kilohertz. This rule prevents a device from concentrating all its energy into a tiny bandwidth, which would likely jam other receivers.
It ensures the total energy of a signal is distributed broadly enough to facilitate spectrum sharing.
Spectral Width
Measurements for the power spectral density cap look for the tallest peak on a signal trace across the operating band. Devices must adjust their output levels if a concentrated signal exceeds the ceiling set by regional wireless laws. If an engineer optimizes a signal for range, they might inadvertently cross this boundary by narrowing the transmission filter too much.
Software based frequency spreading techniques allow for higher overall wattage without breaking the local limit.
Noise Influence
Maintaining levels below the power spectral density cap helps keep the total environmental noise floor at a manageable level. High levels in one specific slot prevent nearby sensors from distinguishing valid signals from background clutter. Testing confirms that no narrow emissions exist that could cause interference with sensitive neighbor bands.
Verification happens in an anechoic chamber using a calibrated peak power measurement tool.
Certification Standard
Every regulatory application must list the maximum value discovered relative to the allowed power spectral density cap for that equipment class. These figures provide a standard reference for hardware integrators deciding how to configure their radio drivers. If a module fails to stay below the line, firmware must limit the maximum gain to comply.
Records show a safe margin remains between the measured signal peak and the legal requirement.