Multipath Channel

Signal propagation in a multipath channel.

multipath channel

Description

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

Ports

Input

# X — signal transmitted through the multipath channel
vector | matrix N on M

Details

A signal transmitted through a multipath channel, given as a vector or matrix of dimension by .

Data types	`Float64`.
Complex numbers support	No

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

Details

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

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

Data types	`Float64`.
Complex numbers support	No

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

Details

Doppler shifts for each path, given as a vector on or a matrix.

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

Data types	`Float64`.
Complex numbers support	No

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

Details

Attenuation (loss) for each path, given as a vector or matrix at .

If a matrix is given, the first column Aloss of elements contains the 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 propagation site during the current time period
vector' | `matrix N over M

Details

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

If it takes more time to propagate the signals from the source to the destination than the current time period, the output data does not contain contributions from the input data of the current time period.

Data types	`Float64`.
Complex numbers support	No

Parameters

Main

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

Details

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

Example: 1000

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

# Sample rate (Hz) — sampling frequency
Real number

Details

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

Example: 3e3

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

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

Details

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

If Auto is specified, the channel automatically allocates enough memory to simulate propagation delay.
If Property is set - the Maximum Delay parameter specifies the maximum propagation delay time, 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

Maximum signal propagation delay, specified 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 delay/compression
Linear | Oversample

Details

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

When Linear is set, the input signal is linearly interpolated directly onto a uniform grid for signal propagation.
If set to Oversample - the input signal is resampled at a higher frequency before linear interpolation to preserve the shape of the spectrum. For wideband 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.