Hi everyone,

I am working on the **GPS Acquisition and Tracking Using AMD RFSoC Device**
GPS Acquisition and Tracking Using AMD RFSoC Device – MATLAB & Simulink
reference design from MATLAB & Simulink, and I have run into a puzzling issue with the ADC path. I would really appreciate any insights from those who have worked with this design or with RFSoC ADC/DAC configurations in general.

**What Works**
In **loopback mode** (ADC input connected directly to DAC output), the system works perfectly — I can see correct PRN codes being acquired through the internal signal generator path.

**The Problem**
When I **disconnect the DAC** and feed real GPS data into the ADC (from a BladeRF via antenna or wire), I get **incorrect PRN codes**. The strange part is:

> **Even when the ADC is fully disconnected, I see those exact same wrong PRNs in the ILA (Integrated Logic Analyzer).**

This strongly suggests the issue is **not** with the incoming RF signal itself, but rather something internal — possibly a signal path that is not being properly muxed or gated when switching away from loopback, or a residual/default signal being driven onto the AXI-Stream bus when the ADC input is inactive.Hi everyone,

I am working on the **GPS Acquisition and Tracking Using AMD RFSoC Device**
GPS Acquisition and Tracking Using AMD RFSoC Device – MATLAB & Simulink
reference design from MATLAB & Simulink, and I have run into a puzzling issue with the ADC path. I would really appreciate any insights from those who have worked with this design or with RFSoC ADC/DAC configurations in general.

**What Works**
In **loopback mode** (ADC input connected directly to DAC output), the system works perfectly — I can see correct PRN codes being acquired through the internal signal generator path.

**The Problem**
When I **disconnect the DAC** and feed real GPS data into the ADC (from a BladeRF via antenna or wire), I get **incorrect PRN codes**. The strange part is:

> **Even when the ADC is fully disconnected, I see those exact same wrong PRNs in the ILA (Integrated Logic Analyzer).**

This strongly suggests the issue is **not** with the incoming RF signal itself, but rather something internal — possibly a signal path that is not being properly muxed or gated when switching away from loopback, or a residual/default signal being driven onto the AXI-Stream bus when the ADC input is inactive. Hi everyone,

I am working on the **GPS Acquisition and Tracking Using AMD RFSoC Device**
GPS Acquisition and Tracking Using AMD RFSoC Device – MATLAB & Simulink
reference design from MATLAB & Simulink, and I have run into a puzzling issue with the ADC path. I would really appreciate any insights from those who have worked with this design or with RFSoC ADC/DAC configurations in general.

**What Works**
In **loopback mode** (ADC input connected directly to DAC output), the system works perfectly — I can see correct PRN codes being acquired through the internal signal generator path.

**The Problem**
When I **disconnect the DAC** and feed real GPS data into the ADC (from a BladeRF via antenna or wire), I get **incorrect PRN codes**. The strange part is:

> **Even when the ADC is fully disconnected, I see those exact same wrong PRNs in the ILA (Integrated Logic Analyzer).**

This strongly suggests the issue is **not** with the incoming RF signal itself, but rather something internal — possibly a signal path that is not being properly muxed or gated when switching away from loopback, or a residual/default signal being driven onto the AXI-Stream bus when the ADC input is inactive. gps, rfsoc, hdl coder, soc, matlab, simulink, hdl, c/a code MATLAB Answers — New Questions

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