MATLAB: Where can I find an NCO (numerically controlled oscillator) block in the Communications Blockset

communications blocksetcontrollednconumericallyoscillator

I am unable to find an NCO (numerically controlled oscillator) block in the Communications Blockset.

Best Answer

An NCO (numerically controlled oscillator) block is not available in the Communications Blockset Library. This block was added to Signal Processing Blockset 6.2 (R14SP3) and later versions.

The following is a link to documentation of DSP.NCO class in DSP System Toolbox 8.0 (R2011a)

http://www.mathworks.com/help/releases/R2011a/toolbox/dsp/ref/dsp.ncoclass.html

This block is also available in the GSM digital down-converter demo model. You can access this demo model by typing:

dspddc

At the MATLAB Command Prompt. There is an NCO block (subsystem) implementation at the top level of this model.

Please note that as of R2011a, Communications Blockset and Communications Toolbox are merged and renamed Communications System Toolbox and that the Communications System Toolbox requires the DSP System Toolbox.

To know more about R2011a license related changes please refer to the following document

http://www.mathworks.com/help/releases/R2011a/base/relnotes/brsz3y4-1.html

Related Solutions

MATLAB: Which mixer (Circuit Envelop/ Idealized baseband/ Equivalent Baseband from SimRF blocksets) is best suited for single carrier frequency input with imperfections such as noise/clipping in SimRF 3.2 (R2012a)

Idealized baseband mixer has built-in frequency-dependent phase noise. It might be simpler to use for a single-frequency system with a known phase noise model.

Equivalent Baseband mixer is more general, because it allows the arbitrary oscillator signal (see, for example, the phase noise block in the 'simrf_low_if' demo). The "phase noise" block is used as a noisy oscillator to the two mixers in Hartley Receiver.

With respect to circuit envelope mixer, the closest demo which will explain more is 'simrf_friis'. There you can see the simple chain, where the signal is downconverted by a mixer and a noiseless oscillator.

Idealized baseband mixer would be more suited with respect to single frequency system.

MATLAB: How is the dithering generated and applied for the NCO (numerically controlled oscillator) block in Signal Processing Blockset 6.5 (R2007a)

The NCO dither generation is based on the PN Sequence Generator block in Communications Blockset. More information on the algorithms used in the PN Sequence Generator block is available in the documentation.

The NCO dither generator is based on the 19th order generator polynominal:

 z^19 + z^18 + z^17 + z^14

with an initial state = 1

For example, when we need a 4-bit dither, we generate 4 consecutive bits from the PN sequence generator. On the next sample hit, we use the next 4 generated bits.

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Related Solutions

MATLAB: Which mixer (Circuit Envelop/ Idealized baseband/ Equivalent Baseband from SimRF blocksets) is best suited for single carrier frequency input with imperfections such as noise/clipping in SimRF 3.2 (R2012a)

MATLAB: How is the dithering generated and applied for the NCO (numerically controlled oscillator) block in Signal Processing Blockset 6.5 (R2007a)

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