in3C In the certification scope,0808 category covers colour TV receivers of various imaging methods and set-top boxes products. Because of the new editionGB/T 9254-2021 taking effect, the old edition ofGB/T13837 must be upgraded. Test differences and upgrade requirements for this product type: test differences and upgrade test requirements:
1. AC mains port
Old standard (GB/T13837-2012）：EUT receive wanted broadcast signals via open-circuit reception or an isolating transformer; tests shall beRF tested with the RF coaxial outer conductor grounded and ungrounded; during measurementEUT with the front of the screen toward the vertical coupling plane.
New standard (GB/T9254.1-2021）：EUT viaAAN (orIEC61000-4-6 specified inCDN) receive wanted broadcast signals; no need toRF tested with the RF coaxial outer conductor grounded; during measurementEUT with the rear ports toward the vertical coupling plane.
2. TV-receiver tuner port
（1) Asymmetrical (common-mode) conducted emissions (new item)
Old standard (GB/T13837-2012): No requirement.
New standard (GB/T9254.1-2021): this item is added and may be tested with anA8.2 required inAAN tested.
（2) Conducted differential-mode emissions (former antenna-port disturbance voltage)
Old standard (GB/T13837-2012): measured on multiple channels in digital reception mode.
New standard (GB/T9254.1-2021): formal tests on one channel that produces maximum emission in each reception mode (analogue,DVB-C、DTMB etc.) that produces maximum emission.
3.Wired network ports:
（1) Telecom port (RJ45) Asymmetrical (common-mode) conducted emissions
Old standard (GB/T9254-2008): port operating at more than10% or more.
New standard (GB/T9254.1-2021): for100Mbps /1000 Mbps interfaces shall be tested at the highest rate; for10M interfaces, same as the old standard.
4. Fibre ports with metal screen or strength members (e.g. laser TVs with such ports)
（1) Asymmetrical (common-mode) conducted emissions (new item)
Old standard (GB/T9254-2008): No requirement.
New standard (GB/T9254.1-2021): this item is added, using aA8.3 current probe meeting the requirements.
5. Enclosure port
（1）1GHz radiated emissions below
Old standard (GB/T13837-2012): receiving antenna vertically polarized, height from2to4 m scan; LO fundamental and harmonic limits were relaxed; test distance is from the EUT centre to the antenna calibration reference.
New standard (GB/T9254.1-2021): receiving antenna vertically polarized, height changed to1to4 m scan; the fundamental and harmonic of the local oscillator are no longer relaxed; test distance is from the imaginary circular boundary in the figure to the antenna calibration reference.
（2）. 1GHz radiated emissions above
Old standard (GB/T9254-2008): displayed image is a full-screen character“H” scrolling pattern; test distance is from the EUT centre to the antenna calibration reference.
New standard (GB/T9254.1-2021): the displayed image preferably uses colour bars with a moving-picture element; test distance is from the imaginary circular boundary to the antenna calibration reference.
