dsp.UniformEncoder System object

Quantize and encode floating-point input into integer output

Description

The UniformEncoder object quantizes floating-point input, using the precision you specify in the NumBits property, and encodes the quantized input into integer output. The operations of the uniform encoder adhere to the definition for uniform encoding specified in ITU-T Recommendation G.701.

To quantize and encode a floating-point input into an integer output:

1. Define and set up your uniform encoder. See Construction.

2. Call step to encode the input according to the properties of dsp.UniformEncoder. The behavior of step is specific to each object in the toolbox.

Note

Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Construction

ue = dsp.UniformEncoder returns a uniform encoder, ue, that quantizes floating-point input samples and encodes them as integers using 2N-level quantization, where N is an integer.

ue = dsp.UniformEncoder('PropertyName',PropertyValue,...) returns an uniform encoder, ue, with each specified property set to the specified value.

ue = dsp.UniformEncoder(peakvalue,numbits,
'PropertyName',PropertyValue,...) returns a uniform encoder, ue, with the PeakValue property set to peakvalue, the NumBits property set to numbits, and other specified properties set to the specified values.

Properties

PeakValue	Largest input amplitude to be encoded Specify the largest input amplitude to be encoded, as a nonnegative numeric scalar. If the real or imaginary input are outside of the interval [–P,(1 – 2(1 – B))P], where P is the peak value and B is the value of the NumBits property, the uniform encoder saturates (independently for complex inputs) at those limits. The default is 1.
NumBits	Number of bits needed to represent output Specify the number of bits needed to represent the integer output as an integer value between 2 and 32. The number of levels at which the uniform encoder quantizes the floating-point input is 2B, where B is the number of bits. The default is 8.
OutputDataType	Data type of output Specify the data type of the output as Unsigned integer or Signed integer. Unsigned outputs are uint8, uint16, or uint32, and signed outputs are int8, int16, or int32. The quantized inputs are linearly (uniformly) mapped to the intermediate integers in the interval [0,2(B – 1)] when you set this property to Unsigned integer, and in the interval [–2(B – 1),2(B – 1) – 1] when you set this property to Signed integer. The variable B in both expressions corresponds to the value of the NumBits property.

Methods

step	Quantize and encode input

Common to All System Objects
release	Allow System object property value changes

Examples

Encode a Sequence Of Numbers

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

ue = dsp.UniformEncoder;
ue.PeakValue = 2;
ue.NumBits = 4;
ue.OutputDataType = 'Signed integer';
x = (-1:0.01:1)'; % Create an input sequence
x_encoded = ue(x);
plot(x, x_encoded,'.');
xlabel('Input'); ylabel('Encoded Output'); grid

Algorithms

This object implements the algorithm, inputs, and outputs described on the Uniform Encoder block reference page. The object properties correspond to the block parameters.