phased.Receiver
Description
The phased.Receiver
System object™ models a multichannel receiver. The object supports system-level multi-channel
receiver chains that include impairments such as nonlinear gain, system noise, and phase
offsets.
To create a receiver
Create the
phased.Receiver
object and set its properties.Call the object with arguments, as if it were a function.
To learn more about how System objects work, see What Are System Objects?
Creation
Description
creates a receiver
System object, recvr
= phased.Receiverrecvr
.
creates a receiver System object
recvr
= phased.Receiver(Name
=Value
)recvr
with each specified property Name
set to
the specified Value
. You can specify additional name-value pair
arguments in any order as (Name1
=Value1
, …
,NameN
=ValueN
).
Properties
The order that receiver effects are applied to the signal is fixed. The following list describes the order in which effects are applied to the input signal. All properties need not be included but if they are, they will be applied in this order regardless of the order in which their properties are listed::
System noise is added according to the method specified in
NoiseMethod
property.The signal gain is applied according to the method specified in
GainMethod
property. This gain may be linear or non-linear as a function of input power.A phase offset is added to the signal according to the
PhaseOffset
property.
Properties can be applied to N channels by specifying properties as an N-element vector. If a property is specified as a scalar, it will be expanded to match the size of vector properties. Scalars are expanded to length-N vectors containing the scalar value.
Unless otherwise indicated, properties are nontunable, which means you cannot change their
values after calling the object. Objects lock when you call them, and the
release
function unlocks them.
If a property is tunable, you can change its value at any time.
For more information on changing property values, see System Design in MATLAB Using System Objects.
EnableInputPort
— Enable receiver input port
false
(default) | true
Set this property to true
to allow the receiver to accept input
when the enabling signal, EN
, argument is on.
Example: EnableInputPort=true
Data Types: logical
AddInputNoise
— Add noise to input signal
false
(default) | true
If set to true
, noise is added to the input signal prior to
applying receiver effects. The InputNoiseTemperature
property
determines the power of the added noise. The SampleRate
property
determines the noise bandwidth.
Example:
true
Data Types: logical
InputNoiseTemperature
— Input noise temperature
290
(default) | positive scalar | length-N vector of positive values
Input noise temperature, specified as a positive scalar or
length-N vector of positive values where N is
the number of receiver channels. If InputNoiseTemperature
is a
scalar, the same value is applied to all channels. Units are in Kelvin degrees.
All properties
Example: 300
Dependencies
To enable this property, set the AddInputNoise
property to
true
.
Data Types: single
| double
NoiseMethod
— Noise method
'Noise figure'
(default) | 'None'
| 'Noise factor'
| 'Noise temperature'
Method for defining the system noise, specified as 'None'
, 'Noise figure'
, 'Noise factor'
or 'Noise temperature'
.
When set to
'None'
, no noise is applied.When set to
'Noise figure'
, theNoiseFigure
property determines the noise level.When set to
'Noise temperature'
, theNoiseTemperature
property determines the noise level.When set to
'Noise factor'
, theNoiseFactor
property determines the noise level.
The noise bandwidth is derived from the input signal sample rate.
Example: 'Noise figure'
Data Types: char
| string
NoiseFigure
— Noise figure
3
(default) | real scalar | length-N vector or real values
Receiver noise figure, specified as a real scalar or length-N
vector of real values. N is the number of channels. If
NoiseFigure
is a scalar, the same value is applied to all
channels. Noise is generated with respect to the temperature defined by the
ReferenceTemperature
property.
Dependencies
To enable this property, set the NoiseMethod
to
'Noise figure'
.
Data Types: single
| double
NoiseFactor
— Noise factor
2
(default) | positive scalar | length-N vector of positive values
Receiver noise factor, specified as a positive scalar or length-N
vector of positive values. N is the number of channels. If
NoiseFactor
is a scalar, the same value is applied to all
channels. Noise is generated with respect to the temperature defined by the
ReferenceTemperature
property.
Dependencies
To enable this property, set the NoiseMethod
property to
'Noise factor'
.
Data Types: single
| double
NoiseTemperature
— Equivalent noise temperature
290
(default) | positive scalar | length-N vector of positive values
Equivalent noise temperature, specified as a positive scalar or length-N vector of positive values. N is the number of channels. If NoiseTemperature
is a scalar, the same value is applied to all channels. Units are in K.
Dependencies
To enable this property, set the NoiseMethod
to 'Noise temperature'
.
Data Types: single
| double
ReferenceTemperature
— Reference temperature
290
(default) | positive scalar | length-N vector of positive values
Reference temperature, specified as a positive scalar or a length-N vector of positive values. N is the number of channels. If ReferenceTemperature
is a scalar, the same value is applied to all channels.
Dependencies
To enable this property, set the NoiseMethod
property to 'Noise figure'
or 'Noise factor'
.
Data Types: single
| double
SampleRate
— Sample rate
1e6
(default) | positive scalar
Sample rate of the input signal, specified as a positive scalar. Use this property to add noise to the signal. The SampleRate
is only used to derive the noise bandwidth of the signal.
Dependencies
To enable this property, set the AddInputNoise
property to true
or set the NoiseMethod
property to 'Noise figure'
, 'Noise factor'
, or 'Noise temperature'
.
Data Types: single
| double
GainMethod
— Gain method
'Linear'
(default) | 'Cubic polynomial'
| 'Lookup table'
Method for applying gain to the received signal, specified as
'Linear'
, 'Cubic polynomial'
or 'Lookup
table'
.
When set to
'Linear'
, linear gain is applied.When set to
'Cubic polynomial'
, a cubic polynomial model is used to apply non-linear gain.When set to
'Lookup Table'
, a lookup table is defined to directly specify output power and phase shift as a function of input power.
Data Types: char
| string
Gain
— Receiver gain
20
(default) | real scalar | length-N vector of real values
Linear receiver gain, specified as a real scalar or length-N
vector of real values. N is the number of channels. If
Gain
is a scalar, the same value is applied to all channels.
Units are in dB.
Dependencies
To enable this property, set the GainMethod
property to
'Linear'
or 'Cubic polynomial'
.
Data Types: single
| double
OIP3
— Output IP3
Inf
(default) | scalar | length-N vector of real values
Output third-order intercept point (OIP3). specified as a scalar or length-N vector of real values. N is the number of channels. OIP3 expresses the non-linearity of the transmitter or receiver. If OIP3 is a scalar, the same value is applied to all channels. See Nonlinearities and Noise in Idealized Baseband Amplifier Block (RF Blockset) for a detailed discussion of OIP3. Units are in dBm.
Dependencies
To enable this property, set the GainMethod
property to 'Cubic polynomial'
.
Data Types: single
| double
Table
— AM/AM-AM/PM lookup table
[-25, 5, -1; -10, 20, -2; 0, 27, 5; 5, 28,
12]
(default) | M-by-N real-valued matrix | M-by-N real-valued matrix
AM/AM-AM/PM lookup table, specified as a 3-by-M-by-N real-valued array. The lookup table specifies amplifier power characteristics. M is the number of table entries and N is the number of channels. Each row in the table expresses the relationship between output power or phase change as a function of input power. Specify AM/AM (in dB/dB) and AM/PM (in deg/dB) characteristics in a [Pin(dBm),Pout(dBm),Phase shift(degrees)]-by-M matrix or [Pin(dBm),Pout(dBm),Phase shift(degrees)]-by-M-by-N array. Use the table to linear interpolate or extrapolate power values. The column 1 input power must increase monotonically. There must be at least 3 rows in the table. The power output can be written as:
Dependencies
To enable this property, set the GainMethod
property to
'Lookup table'
.
Data Types: single
| double
PhaseOffset
— Phase offset
0
(default) | scalar | length-N vector of real values
Phase offset, specified as a real scalar or length-N vector of real values. N is the number of channels. If PhaseOffset
is a scalar, the same value is applied to all channels. Units are in degrees.
Data Types: single
| double
SeedSource
— Source of seed for random number generator
'Auto'
(default) | 'Property'
Source of random generator seed, specified as 'Auto'
or
'Property'
. When you set this property to
'Auto'
, random numbers are generated using the default MATLAB random
number generator. When you set this property to 'Property'
, a private
random number generator is used with a seed specified by the value of the
Seed
property. To use this object with Parallel Computing Toolbox™, set this property to 'Auto'
.
Data Types: single
| double
Seed
— Seed for random number generator
0
(default) | nonnegative integer
Seed for the random number generator, specified as a nonnegative integer less than 2^32.
Dependencies
To enable this property, set the SeedSource
property to
'Property'
.
Data Types: single
| double
Usage
Description
Input Arguments
X
— Receiver Input signal voltage
complex-valued vector | complex-valued matrix
Receiver Input signal voltage, specified as a complex-valued vector or complex-valued matrix. The number of rows is equal to the number of samples.
If X
is a vector, the number of rows in
Y
equals the number of rows in X
.The
number of columns in Y
equals the number of channels in the
receiver.
In the case where X
is a vector, the number of channels is
determined by the active properties that indicate a number of channels, such as
NoiseFigure
, ReferenceTemperature
,
Gain
, or PhaseOffset
.
Receiver effects are applied to the signal in a fixed order although some effects can be omitted. The order in which effects are applied to the input signal:
Set input signal to
false
for any disabled points if theEnableInputPort
property istrue
.Input noise is added according to the
AddInputNoise
property.System noise is added according to the method specified in
NoiseMethod
property.Signal gain is applied according to the method specified in the
GainMethod
property.Phase offset is added to the signal according to
PhaseOffset
property.
Data Types: single
| double
Complex Number Support: Yes
EN
— Enabling signal
real-valued vector (default) | real-valued matrix | logical-valued vector | logical-valued matrix
Enabling signal, specified as a real-valued vector or matrix or logical-valued vector or matrix.
If
EN
is a vector, it must have the same number of rows as the input signal matrixX
. Then, the value in each row ofEN
is applied to all the columns ofX
.If
EN
is a matrix,EN
must be the same size asX
, and each element inEN
is applied to the corresponding element inX
.
If EN
is of type single or double, when an element of
EN
is zero,the receiver is turned off, and the input signal is
set to zero. When element of EN
is nonzero, the receiver is
turned on, and the input passes through the receiver.
If EN
is logical, the receiver is enabled whenever an element
of EN
is true
and disabled whenever an element
of EN
is false
.
Dependencies
To enable this argument, set the EnableInputPort
property
to true
.
Data Types: double
| single
| logical
Output Arguments
Y
— Receiver output signal voltage
complex-valued vector | complex-valued matrix
Receiver output signal voltage, returned as a complex-valued vector or
complex-valued matrix. If X
is a matrix, the size of
Y
is equal to the size of X
. The
transformation is based on transmitter characteristics, such as the gain,
nonlinearity, and noise. Power is calculated from signal voltage assuming a reference
impedance of 1 Ohm.
Data Types: single
| double
Complex Number Support: Yes
Object Functions
To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named obj
, use
this syntax:
release(obj)
Specific to phased.Receiver
viewGain | Plot output receiver power or output phase shift as a function of input receiver power |
Examples
Display Waveform with Single Channel Receiver
Display a waveform that is output from a single-channel receiver having linear gain. Specify noise setting the NoiseMethod property to 'Noise figure'
.
fs = 1e7;
waveform = phased.LinearFMWaveform(SampleRate=fs, ...
PulseWidth=1e-5,SweepBandwidth=5e6);
sig = waveform();
Create a receiver object. Apply a 20 dB gain and then add noise to the waveform.
recvr = phased.Receiver(AddInputNoise=true,InputNoiseTemperature=200, ... GainMethod="Linear",Gain=20,NoiseMethod="Noise figure", ... NoiseFigure=5,SampleRate=1e6,PhaseOffset=0);
Pass the waveform through the receiver to create the processed waveform.
y = recvr(sig);
Plot the absolute value of the original waveform and the amplified waveform as a function of time.
dt = 1/fs; n = length(sig); t = (0:(n-1))*dt*1e6; plot(t,abs(sig)) hold on plot(t,abs(y)) hold off legend('Original waveform','Amplified waveform') xlabel('Time (microsec)') ylabel('Signal')
Model Two-Channel Receiver
Receive a linear FM waveform with a two-channel receiver where the behavior varies between each channel. Use a cubic polynomial gain model to simulate non-linear gain behavior and specify noise using noise temperature. The receiver sample rate is 10 Mhz.
fs = 10e6;
waveform = phased.LinearFMWaveform(SampleRate=fs, ...
PulseWidth=1e-5,SweepBandwidth=5e6);
x = waveform();
Create the two channel receiver.
recvr = phased.Receiver(GainMethod="Cubic polynomial",Gain=[19,21], ... OIP3=[30,32],NoiseMethod="Noise temperature", ... NoiseTemperature=[290,350],SampleRate=fs,PhaseOffset=[0,15]);
Pass the waveform through the receiver.
y = recvr(x); viewGain(recvr,ChannelIndex=1,Parent=gca); hold on viewGain(recvr,ChannelIndex=2,Parent=gca); legend('Channel 1, Gain = 19','Channel 2, Gain = 21', ... 'Location','SouthEast') hold off
More About
Comparison between phased.Receiver and phased.ReceiverPreamp
You can use the phased.Receiver
System object in place of the phased.ReceiverPreamp
in many case. Here
are some guidelines for replacing phased.ReceiverPreamp
properties by equivalent phased.Receiver
properties.
You can replace the
Gain
property of thephased.ReceiverPreamp
System object with theGain
property of thephased.Receiver
but first you must specify that the gain is linear. To do this, set theGainMethod
property of thephased.Receiver
to"Linear"
.There is no property in
phased.Receiver
equivalent to theLoss
property of thephased.ReceiverPreamp
. Loss can be obtained by offsetting theGain
.Both the
phased.ReceiverPreamp
and thephased.Receiver
System objects lets you add noise to the receiver output. You can obtain equal noise powers by proper choice of the properties of each objectFor the
phased.ReceiverPreamp
, you can specify the noise using theNoiseMethod
property set to either"Noise power"
or"Noise temperature"
.Setting the
NoiseMethod
property to"Noise temperature"
adds complex baseband noise to the input signal. The quantityrepresents the noise power computed from the (TRef), the
NoiseFactor
(F), and theSampleRate
(fs) properties. The noise bandwidth (BW) is one-half the sample rate.Setting the
NoiseMethod
property to"Noise power"
lets you specify the noise power (NP) directly using theNoisePower
property.
The
phased.Receiver
System object does not have a"Noise power"
option available in itsNoiseMethod
property. The only options are"Noise figure"
,"Noise factor"
,"None"
, and"Noise temperature"
.When the
NoiseMethod
property is set to"Noise temperature"
, use theNoiseTemperature
property to derive the noise power. The noise power (NP) iswhere k is Boltzmann's constant, TN is the noise temperature given by the
NoiseTemperature
property, and the bandwidth (BW) is one-half the sample rate.When the
NoiseMethod
property is set to"Noise figure"
or"Noise factor"
, the noise power can be derived using either quantity. First compute the noise factorwhere TN is the noise temperature set by the
NoiseTemperature
property and TRef is the reference temperature set by theReferenceTemperature
property. Compute the noise temperaturefrom the noise factor (F). Using this expression for the noise temperature, obtain the noise power
completely in terms of the noise factor.
Instead of the noise factor you can use the noise figure (in dB) FdB. The noise figure is related to the noise factor (F) by
and can be used when the
NoiseMethod
property is set to"Noise figure"
.
Because of how the
phased.ReceiverPreamp
adds noise to the signal, the System object does not apply noise correctly. Thephased.ReceiverPreamp
System object adds noise to the signal after applying the gain. In contrast, thephased.Receiver
System object adds noise to the signal before applying the gain.Referring back to the general form of the noise factor,
set the noise factor of the
phased.Receiver
so that its output noise power equals the output noise factor of thephased.ReceiverPreamp
.To obtain the same output noise power, you must adjust the noise factor F (or equivalently the noise figure).
Algorithms
Output third-order intercept point (OIP3)
Cubic polynomials can be used to model nonlinear amplifier power gain. The general form of the cubic nonlinear AM-AM amplifier is characterized by
where u is the input power and
FAM-AM(u) is the output
power. c1 represents the linear gain in the
Gain
property.
and OIP3 is the third-order intercept point specified by the
OIP3
property.
Lookup Table
A lookup table expresses the relationship between output power or phase change as a function of input power at discrete points. The table contains values for TAM-AM and TAM-PM. The output power is derived by linear interpolation or extrapolation of
between these values.
References
[1] Mark Richards, Fundamentals of Radar Signal Processing, McGraw-Hill, 2005.
[2] Merrill Skolnik, Introduction to Radar Systems, 3rd Ed., McGraw-Hill, 2001.
[3] Byron Edde, Radar: Principles, Technology, Applications, Prentice Hall, 1993.
[4] Behzad Razavi, RF Microelectronics, Second Edition, Wiley, 2012.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
See System Objects in MATLAB Code Generation (MATLAB Coder).
Version History
Introduced in R2024a
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