Kenwood TS-590S manual Overview of Noise Reduction, 11 NB2 Inactive

4 DSP

Figure 4-11 NB2: Inactive

Figure 4-12 NB2: Active

However, depending on the nature of the pulse noise, the noise blanker cannot suppress the noise effectively. In such a case, by using other methods such as noise reduction in conjunction, the reception conditions may be improved.

4.6.3 Overview of Noise Reduction

There are two methods available for noise reduction on TS-590S: NR1 and NR2. You can select the noise reduction that is more effective depending on the operation mode and reception conditions.

NR1 has different algorithms that operate according to the operation mode: in voice modes (SSB, FM and AM), a newly developed noise reduction method featuring audio signals based on spectral subtraction is used. In non-voice modes (CW and FSK), noise reduction is based on a line enhancer using an adaptive filter that emphasizes the periodic signal. The noise reduction is automatically switched over when an operation mode is selected.

On the other hand, NR2 employs what is known as SPAC (speech processing by auto correlation) to piece together only the periodic components detected from the RX signal and to produce the result as audio output. Table 4-1 provides the relationship between the RX modes and NR algorithms used.

Table 4-1 Reception Modes and NR Algorithms Used

Noise Reduction		Receive Mode
	SSB/ SSB DATA	FM/ AM	CW/ FSK
NR1	Spectral subtraction	Spectral subtraction	Line enhancer
NR2	SPAC	SPAC	SPAC

TS-590S

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