Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
CISPR 13: Sound and Television Broadcast Receivers — Radio Disturbance Characteristics
Emission limits and measurement methods for broadcast receiver equipment
1. Standard Scope and Historical Context
CISPR 13 specifies limits and measurement methods for radio disturbance emissions from sound and television broadcast receivers. Historically, this was one of the earliest CISPR standards, recognizing that broadcast receivers were both susceptible to interference and could themselves generate interference through local oscillator radiation and intermediate frequency leakage. The standard applies to terrestrial TV receivers, FM/AM radio receivers, and associated devices such as set-top boxes, satellite receivers, and streaming media adapters that include broadcast tuner functionality.
While the original focus was on protecting broadcast reception, modern editions address the full 150 kHz to 18 GHz range and cover both conducted and radiated emissions from the tuner, local oscillator, digital processing sections, and power supply. Many requirements originally in CISPR 13 have been harmonized with or superseded by CISPR 32 (multimedia equipment EMC), but CISPR 13 remains relevant for regulatory compliance in several jurisdictions.
The local oscillator (LO) leakage from a TV tuner was historically the dominant interference source. Modern silicon tuners with integrated phase-locked loops and fully shielded package designs have reduced LO leakage by 30–40 dB compared to traditional can-type tuners.
2. Emission Limits and Key Measurement Parameters
CISPR 13 defines specific limits for both the antenna terminal (conducted) and cabinet (radiated) emissions. The antenna terminal limits are critical because the antenna is the most efficient radiator — any noise coupled to the antenna input is directly radiated.
| Frequency Range | Limit (dBµV) Quasi-Peak | Measurement Port | Applicability |
|---|---|---|---|
| 150 kHz – 30 MHz | 46–70 (varies by band) | Mains terminals | Conducted |
| 30 – 300 MHz | 50–60 | Antenna terminals | Conducted (at antenna port) |
| 300 – 1000 MHz | 54–66 | Antenna terminals | Conducted (at antenna port) |
| 30 – 1000 MHz | 40–57 | Cabinet radiation | Radiated (3 m or 10 m) |
Measurement procedures require the receiver to be tuned to specific frequencies across multiple bands (LW, MW, SW, FM, VHF, UHF) to capture worst-case emissions. The local oscillator frequency and its harmonics are particularly critical, as these are typically the highest emission levels.
A common pitfall in set-top box design is inadequate isolation between the tuner module and the HDMI/USB interface. High-speed digital signals on HDMI can couple directly into the tuner front-end through PCB trace crosstalk, causing both emission failures and degradation of receiver sensitivity.
3. Engineering Design for Compliance
Effective CISPR 13 compliance starts with the tuner module selection. Modern silicon tuners with integrated filtering offer significant advantages over discrete designs. Key PCB layout rules include: keeping the tuner section physically separated from digital processing sections, implementing a solid ground plane under the tuner area, and using guard traces with ground vias around the tuner periphery to contain local oscillator fields.
Antenna input filtering is critical. A band-pass filter at the antenna input (matching the tuner frequency range) attenuates out-of-band emissions while improving receiver selectivity. For multi-tuner devices (e.g., PVRs with dual tuners), inter-tuner isolation must be maintained at >40 dB to prevent one tuner’s LO from desensitizing the other. Power supply filtering deserves special attention — switch-mode power supplies used in modern receivers generate broadband noise that can couple into the tuner section. A two-stage LC filter (L = 2.2 µH, C = 10 µF + 0.1 µF) on the tuner power rail is recommended.
Shielded HDMI connectors with integrated ferrite cores provide measurable emission reduction of 5–10 dB in the 500–800 MHz range. Combined with common-mode filtering on the HDMI differential pairs, this approach effectively addresses the most challenging emission frequencies in modern set-top box designs.
4. Frequently Asked Questions
Q: Is CISPR 13 still actively maintained?
A: While many requirements have been superseded by CISPR 32 (which covers multimedia equipment comprehensively), CISPR 13 remains in effect for specific regulatory programs, particularly in some Asian and African markets, and for dedicated broadcast receivers not covered by the broader multimedia scope.
A: While many requirements have been superseded by CISPR 32 (which covers multimedia equipment comprehensively), CISPR 13 remains in effect for specific regulatory programs, particularly in some Asian and African markets, and for dedicated broadcast receivers not covered by the broader multimedia scope.
Q: Do software-defined radio (SDR) receivers fall under CISPR 13?
A: If the SDR includes a tuner front-end designed for broadcast reception, it generally falls within the scope. SDRs that are general-purpose RF receivers without specific broadcast tuning capability may be assessed under CISPR 32 or other applicable standards.
A: If the SDR includes a tuner front-end designed for broadcast reception, it generally falls within the scope. SDRs that are general-purpose RF receivers without specific broadcast tuning capability may be assessed under CISPR 32 or other applicable standards.
Q: What is the most common cause of CISPR 13 compliance failure?
A: Local oscillator harmonic leakage remains the most common failure mode. Up to the 5th harmonic of the LO (e.g., 5 × 1 GHz for a UHF tuner) can exceed limits. Proper shielding and filtering of the tuner module is essential.
A: Local oscillator harmonic leakage remains the most common failure mode. Up to the 5th harmonic of the LO (e.g., 5 × 1 GHz for a UHF tuner) can exceed limits. Proper shielding and filtering of the tuner module is essential.
