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IEC 60244-15: Radio Transmitter Measurements — Modulation Characteristics for Digital TV
MER: The Single Number That Defines Digital TV Signal Quality
IEC 60244-15 specifies radio transmitter modulation measurement methods. The core digital TV metric is Modulation Error Ratio (MER) — quantifying the deviation between actual and ideal constellation points. MER is the SNR+ of digitally modulated signals — capturing both amplitude and phase errors simultaneously.
| MER (dB) | Quality | Reception |
|---|---|---|
| >35 | Excellent | Zero errors, maximum coverage |
| 32–35 | Good | Normal reception |
| 28–32 | Marginal | Occasional pixelation |
| <28 | Fail | Freeze or no reception |
MER degradation comes from: (1) Power amplifier nonlinearity (AM-AM/AM-PM distortion). (2) Phase noise — LO short-term instability. (3) In-band intermodulation — OFDM high PAPR forces Digital Pre-Distortion (DPD) for PA linearization.
Critical note: MER must be measured at rated output power. Low-power MER is typically 3–5 dB better than full-power. Nameplate MER must be at rated power.
TN Lab — MER is the single true score of digital TV signal quality.
