JVC TDR6 installation and operation guide Information Rate, Spacing

	Data Inversion / Spectral Inversion
	In QPSK modulations, every symbol consists of two bits of data. These two bits
	are commonly referred two as the I and Q samples. Data inversion occurs when
	both I and Q are inverted. Spectral inversion occurs when either I or Q are
	inverted. Spectral inversion is caused by selecting the lower sideband instead of
	the upper sideband in the mixing and RF filtering process.
	All Tiernan demodulators automatically check for and compensate for
	data/spectral inversion.
Information Rate/	This section provides rate definitions and relationships as well as information on
Symbol Rate/Channel	channel spacing.
Spacing	Definitions
	Information Rate (Bits/Sec)
	Information rate is the rate of data leaving the demodulator measured in bits per
	second. For Tiernan systems, the information rate is generally equal to the
	aggregate transport stream rate.
	For the TDR6, the information rate is the data rate parameter.
	Channel Rate (Bits/Sec)
	Channel rate is the rate of data in the demodulator, before the FEC decoding. The
	channel rate equals the information rate plus the FEC encoding overhead
	measured in bits per second.
	Symbol Rate (Symbols/Sec)
	Symbol rate is the rate of symbols being transmitted through the channel
	measured in bits per second. For QPSK modulation, there are 2 bits per symbol.
	You can query the TDR6 symbol rate using the DMD.x SR command. There is no
	front panel equivalent for the SR command.
	Aggregate Rate (Bits/Sec)
	Aggregate data rate is the rate of the encoder output transport stream measured in
	bits per second. The transport stream can be either a single transport stream or
	several multiplexed transport streams. The aggregate rate is generally the
	information rate going into the modulator or coming out of the demodulator.
	Relationships
	Information Rate = Aggregate Rate
	Symbol Rate = 1 ⁄ 2*(204 ⁄ 188)*(1 ⁄ Code Rate)*Information Rate
	where the code_rate can be 1/2, 2/3, 3/4, 5/6, 7/8.
	The minimum required Eb/N0 level varies depending on the code rate. For a table
	showing the relationship between the Eb/N0 level and the code rate, refer to the
	chapter on troubleshooting.
	Maximum Rates
	Symbol Rates
	The minimum and maximum symbol rates are:
	■ Minimum = 1 Mbaud
	■ Maximum = 30 Mbaud

82 01-0870-401B 01/03 Demodulator Application Notes