# Binary ASK Implementation in TINA-TI This guide describes how to implement Binary Amplitude Shift Keying (ASK) modulation and coherent detection in TINA-TI for: - Carrier frequency: **2 kHz** - Bit rate: **10 kbps** - NRZ (Non-Return-to-Zero) pulses (up to 10 bits) ## 1. System Overview - **NRZ Signal:** Digital bitstream (1 or ) at 10 kbps. - **Carrier:** 2 kHz sine wave. - **Modulator:** Multiplies NRZ stream and carrier (ASK). - **Coherent Detector:** Demodulates and recovers original NRZ bits. --- ## 2. Block Diagram ``` NRZ Source --> ASK Modulator --> Transmission --> Coherent Detector --> Recovered NRZ ``` --- ## 3. NRZ Signal Generation - Use a **pulse voltage source** or a **digital signal generator** in TINA-TI. - Set: - **High level:** +1 V (logic '1') - **Low level:** V (logic '') - **Bit rate:** 10 kbps (bit period = 100 µs) - **Pattern:** e.g., 101100101 (10 bits) --- ## 4. Carrier Generation - Use a **sine voltage source**. - Set: - **Frequency:** 2 kHz - **Amplitude:** 1 V\(_{peak}\) (or as desired) --- ## 5. ASK Modulator Circuit - Use a **voltage-controlled switch** or an **analog multiplier** (e.g., AD633) in TINA-TI. - **Inputs:** - **Carrier:** Sine source - **Control:** NRZ pulse - **Operation:** When NRZ = '1', output = carrier; when '', output = . **Schematic Example:** - Connect NRZ signal to the control input of the multiplier. - Connect the carrier to the other input. --- ## 6. Coherent Detector Circuit ### Steps: 1. **Multiply** received ASK signal by a locally generated coherent carrier (same phase/freq as Tx). - Use same sine source as at transmitter. 2. **Low-pass filter** the output to remove high-frequency components and recover the baseband NRZ. **Implementation:** - Use another analog multiplier (AD633). - Feed received ASK and local carrier to multiplier inputs. - Design a **low-pass RC filter**: - Cutoff frequency: slightly above bit rate (\(f_c \approx 15\,\text{kHz}\)) - Example: \(R = 10\,k\Omega,\, C = 1\,nF\) (\(f_c = \frac{1}{2\pi RC}\)) --- ## 7. TINA-TI Circuit Example ### Components List - 2 x **Sine voltage sources** (one for Tx, one for Rx) - 1 x **Pulse voltage source** (NRZ) - 2 x **Analog multipliers** (e.g., AD633) - 1 x **RC low-pass filter** ### Example Layout (Textual) ``` [Pulse Source] --+--> [Multiplier1] --+--> [Multiplier2] --+--> [RC Filter] --> NRZ Output | | | [Sine (2kHz)] ----+ | +-- [Sine (2kHz, coherent)] | [ASK Signal Out] ``` --- ## 8. Simulation Steps 1. **Set up NRZ, carrier, and ASK modulator as above.** 2. **Connect modulated ASK output to the coherent detector circuit.** 3. **Run time-domain simulation.** 4. **Observe:** - NRZ input - ASK modulated signal - Demodulator output (should match NRZ) --- ## 9. Key Points - **Coherent detection** requires local carrier to be phase/frequency-aligned to transmitter. - Use **NRZ bit rate** and **carrier frequency** as specified. - **Low-pass filter** cutoff must sufficiently pass NRZ but block carrier harmonics. --- ## 10. Example Waveforms - **NRZ input:** Square wave, 10 kbps - **ASK output:** Carrier present for '1', absent for '' - **Recovered NRZ:** After filtering, should resemble original NRZ --- ## 11. Troubleshooting - If recovered NRZ is distorted: - Adjust filter cutoff. - Ensure carrier signals are coherent (in phase). - Check multiplier connections and input levels. --- ## 12. References - [TINA-TI User Manual](https://www.ti.com/tool/TINA-TI) - [Analog multiplier (AD633) datasheet](https://www.analog.com/en/products/ad633.html) --- **[Note: Replace block diagrams with actual TINA-TI screenshots for lab reports if available.]**