Multipath Channel

Propagation of signals in a multipath channel.

blockType: MultipathChannel

Path in the library:

/Phased Array Systems/Environment and Target/Multipath Channel

Description

Block Multipath Channel simulates the propagation of a signal over a multipath channel. You can set the time delay, gain, Doppler ratio, reflection loss, and propagation loss for this block.

Ports

Input

# X — a signal transmitted through a multipath channel
vector | the N-by-M matrix

Details

A signal transmitted through a multipath channel, specified as a vector or matrix of dimension on .

Data types	`Float64`
Complex numbers support	No

# Paths — relative delays for each path in a multipath channel
vector | a 3-by-M matrix

Details

Relative delays for each path in a multipath channel, specified as a vector or matrix of dimension on .

If a matrix is specified, then the first row of Paths contains propagation time delays (in seconds), the second contains the total reflection coefficient for each channel due to reflections from the interface, and the third contains scattering losses for each channel in dB.

Data types	`Float64`
Complex numbers support	No

# Dop — Doppler shifts for each path
vector-row 1 on M | matrix

Details

Doppler shifts for each path, specified as a vector on or matrices.

Each Dop element contains a coefficient that multiplies the radiated frequency to obtain the observed frequency shifted according to the Doppler law.

Data types	`Float64`
Complex numbers support	No

# Aloss — attenuation (loss) for each path
vector | the K by M+1 matrix

Details

Attenuation (loss) for each path, specified as a vector or matrix on .

If a matrix is specified, the first column is Aloss of The number of elements contains frequencies in Hz, and the remaining columns contain the absorption loss for each path in dB.

Data types	`Float64`
Complex numbers support	No

Output

# Y — signals arriving at the distribution location during the current time period
vector | the N-by-M matrix

Details

Signals arriving at the propagation location during the current time period, specified as a vector or matrix on .

If it takes longer for the signals to propagate from the source to the destination than in the current time interval, then the output data does not contain contributions from the input data of the current time interval.

Data types	`Float64`
Complex numbers support	No

Parameters

Main

# Operating frequency (Hz) — carrier frequency of the signal
Real number

Details

The carrier frequency of the signal, specified as a positive real scalar.

Example

1000

Default value	`20e3`
Program usage name	`OperatingFrequency`
Tunable	No
Evaluatable	Yes

# Sample rate (Hz) — sampling rate
Real number

Details

The sampling frequency of the signal, set as a positive real scalar.

Example

3e3

Default value	`1e3`
Program usage name	`SampleRate`
Tunable	No
Evaluatable	Yes

# Maximum delay source — The source of the maximum delay
Auto | Property

Details

The source of the maximum delay value specified as Auto or Property.

If the value is set to Auto, the channel automatically allocates enough memory to simulate a propagation delay.
If the value Property is set, the Maximum Delay parameter is used to specify the maximum propagation delay time, and any samples beyond this time are ignored.

Values	`Auto` \| `Property`
Default value	`Auto`
Program usage name	`MaximumDelaySource`
Tunable	No
Evaluatable	No

# Maximum delay (sec) — maximum signal propagation delay
Real number

Details

The maximum signal propagation delay, set as a positive scalar. Delays exceeding this value are ignored.

Dependencies

To use this parameter, set the Maximum delay source parameter to Property.

Default value	`1`
Program usage name	`MaximumDelay`
Tunable	No
Evaluatable	Yes

# Interpolation method — the method used by the channel to implement partial signal delay and Doppler time dilation/compression
Linear | Oversample

Details

When set to Linear, the input signal is linearly interpolated directly into a uniform grid to propagate the signal. When the value Oversample is set, the input signal is resampled at a higher frequency before linear interpolation to preserve the shape of the spectrum.

If the value is set to `Linear', the input signal is linearly interpolated directly onto a uniform grid for signal propagation.
If the value is set to Oversample, the input signal is resampled at a higher frequency before linear interpolation to preserve the shape of the spectrum. For broadband signals, oversampling preserves the shape of the spectrum.

Values	`Linear` \| `Oversample`
Default value	`Linear`
Program usage name	`InterpolationMethod`
Tunable	No
Evaluatable	No

Literature

Urick, R.J. "Principles of Underwater Sound, 3rd Edition." New York: Peninsula Publishing, 1996.
Sherman, C.S. and J. Butler "Transducers and Arrays for Underwater Sound." New York: Springer, 2007.
Allen, J.B. and D. Berkely, "Image method for efficiently simulating small-room acoustics", J. Acoust. Soc. Am, Vol 65, No. 4. April 1979.