Hello,

I am working on a FDMA project using Simulink and I am facing technical issues with the following blocks:
– Sine Wave (Discrete Time)
– Product (BPSK × Carrier)
– Bandpass Filter
– AWGN Channel

**Problem:**
1. When using AWGN Channel with mode "Signal to Noise Ratio", I get:
"Input and output must be discrete when mode set to Signal to Noise Ratio".
2. After the Filter, sometimes complex signals appear causing errors in Integrator or Decision blocks.

**Current settings for User 1 example:**
– Sine Wave: Discrete, Sample time = 0.0001 s
– Filter: Bandpass, Filter order = 4, Lower passband = 900 Hz, Upper passband = 1100 Hz
– Stopband 1 = 800 Hz, Stopband 2 = 1200 Hz, Stopband attenuation = 40 dB
– AWGN Channel: Mode = Signal to Noise Ratio

**Goal:**
– Run FDMA for two users (User1 = 1 kHz, User2 = 2 kHz)
– Avoid any complex signals
– Make AWGN Channel work correctly with specified SNR

**Request:**
– How to set up the blocks (Sine Wave, Product, Filter, AWGN) so that no complex signals appear and AWGN works correctly?
– How to choose the correct Sample time and Filter type for each block?

**Attachments:**
– Simulink screenshots
– Simulink file (.slx) if possible

Thank you very much for your help.

<<

<</matlabcentral/answers/uploaded_files/1845240/IMG_20260101_225640_567.jpg>>

>>Hello,

I am working on a FDMA project using Simulink and I am facing technical issues with the following blocks:
– Sine Wave (Discrete Time)
– Product (BPSK × Carrier)
– Bandpass Filter
– AWGN Channel

**Problem:**
1. When using AWGN Channel with mode "Signal to Noise Ratio", I get:
"Input and output must be discrete when mode set to Signal to Noise Ratio".
2. After the Filter, sometimes complex signals appear causing errors in Integrator or Decision blocks.

**Current settings for User 1 example:**
– Sine Wave: Discrete, Sample time = 0.0001 s
– Filter: Bandpass, Filter order = 4, Lower passband = 900 Hz, Upper passband = 1100 Hz
– Stopband 1 = 800 Hz, Stopband 2 = 1200 Hz, Stopband attenuation = 40 dB
– AWGN Channel: Mode = Signal to Noise Ratio

**Goal:**
– Run FDMA for two users (User1 = 1 kHz, User2 = 2 kHz)
– Avoid any complex signals
– Make AWGN Channel work correctly with specified SNR

**Request:**
– How to set up the blocks (Sine Wave, Product, Filter, AWGN) so that no complex signals appear and AWGN works correctly?
– How to choose the correct Sample time and Filter type for each block?

**Attachments:**
– Simulink screenshots
– Simulink file (.slx) if possible

Thank you very much for your help.

<<

<</matlabcentral/answers/uploaded_files/1845240/IMG_20260101_225640_567.jpg>>

>> Hello,

I am working on a FDMA project using Simulink and I am facing technical issues with the following blocks:
– Sine Wave (Discrete Time)
– Product (BPSK × Carrier)
– Bandpass Filter
– AWGN Channel

**Problem:**
1. When using AWGN Channel with mode "Signal to Noise Ratio", I get:
"Input and output must be discrete when mode set to Signal to Noise Ratio".
2. After the Filter, sometimes complex signals appear causing errors in Integrator or Decision blocks.

**Current settings for User 1 example:**
– Sine Wave: Discrete, Sample time = 0.0001 s
– Filter: Bandpass, Filter order = 4, Lower passband = 900 Hz, Upper passband = 1100 Hz
– Stopband 1 = 800 Hz, Stopband 2 = 1200 Hz, Stopband attenuation = 40 dB
– AWGN Channel: Mode = Signal to Noise Ratio

**Goal:**
– Run FDMA for two users (User1 = 1 kHz, User2 = 2 kHz)
– Avoid any complex signals
– Make AWGN Channel work correctly with specified SNR

**Request:**
– How to set up the blocks (Sine Wave, Product, Filter, AWGN) so that no complex signals appear and AWGN works correctly?
– How to choose the correct Sample time and Filter type for each block?

**Attachments:**
– Simulink screenshots
– Simulink file (.slx) if possible

Thank you very much for your help.

<<

<</matlabcentral/answers/uploaded_files/1845240/IMG_20260101_225640_567.jpg>>

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