DVB QAM (Digital Demod)

Menu Path: MeasSetup > Digital Demod Properties > Format tab > Format: box

Use the Format drop-down list to select a DVB QAMQuadrature Amplitude Modulation format that conforms to the DVB (Digital Video Broadcast (DVB) standard, EN 300 429. The VSA supports the following DVB QAM formats:

The standard defines the bits that represent each state as follows:

• The first two bits are differentially encoded so that pi/2 rotations in the QAM constellation do not affect detection of the two MSBs.
• The LSBs are positioned to be rotation-invariant as defined in EN 300 429

I/Q Origin Offset Compensation

Unlike QAM, DVB QAM does not compensate for I/Q origin offset. When the demodulation format is DVB QAM, the VSA reports I/Q origin offset in the symbol table, but doesn't remove it from the measurement. When the demodulation format is QAM, the VSA reports I/Q origin offset in the symbol table AND removes it from the measurement.

To see the effects of I/Q origin offset on your DVB QAM signal, change the demodulation format to QAM. For example, if your signal is 16 DVB QAM, select 16-QAM to see the effects of I/Q origin offset removal on your signal.

Reliable Carrier Lock

This table shows the minimum result length and frequency offset values for reliable carrier lock for DVB QAM signals:

See Also

Available Digital Demodulation Formats (Digital Demod)