When using the FPGA in post-processing mode, start the DMA after instantiating the complete flowgraph, not before.

src/algorithms/signal_source/adapters/ad9361_fpga_signal_source.cc

@@ -148,8 +148,6 @@ Ad9361FpgaSignalSource::Ad9361FpgaSignalSource(const ConfigurationInterface *con
                 {
                     freq_band = "L1L2";
                 }
-
-            thread_file_to_dma = std::thread([&] { run_DMA_process(freq_band, filename_rx1, filename_rx2); });
         }
     if (switch_position == 2)  // Real-time via AD9361
         {
@@ -368,6 +366,11 @@ Ad9361FpgaSignalSource::~Ad9361FpgaSignalSource()
         }
 }
 
+void Ad9361FpgaSignalSource::start()
+{
+    thread_file_to_dma = std::thread([&] { run_DMA_process(freq_band, filename_rx1, filename_rx2); });
+}
+
 
 void Ad9361FpgaSignalSource::run_DMA_process(const std::string &FreqBand, const std::string &Filename1, const std::string &Filename2)
 {

src/algorithms/signal_source/adapters/ad9361_fpga_signal_source.h

@@ -43,6 +43,8 @@ public:
 
     ~Ad9361FpgaSignalSource();
 
+    void start();
+
     inline std::string role() override
     {
         return role_;

src/core/interfaces/gnss_block_interface.h

@@ -68,6 +68,11 @@ public:
             };           // avoid unused param warning
         return nullptr;  // added to support raw array access (non pure virtual to allow left unimplemented)= 0;
     }
+
+    /*!
+     * \brief Start the flow of samples if needed.
+     */
+    virtual void start(){};
 };
 
 #endif  // GNSS_SDR_GNSS_BLOCK_INTERFACE_H

src/core/receiver/gnss_flowgraph.cc

@@ -110,6 +110,10 @@ void GNSSFlowgraph::start()
             return;
         }
 
+#ifdef ENABLE_FPGA
+    sig_source_.at(0)->start();
+#endif
+
     running_ = true;
 }