fm-rds-tx/examples/soapy_simulated/main.go

package main

import (
	"context"
	"encoding/binary"
	"fmt"
	"os"
	"time"

	"github.com/jan/fm-rds-tx/internal/output"
	"github.com/jan/fm-rds-tx/internal/platform"
)

func main() {
	ctx := context.Background()

	fb, err := output.NewFileBackend("examples/simulated_mpx.iq", binary.LittleEndian, output.BackendInfo{
		Name:        "example-file",
		Description: "Captures simulated Soapy output for later playback.",
	})
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to open file backend: %v\n", err)
		os.Exit(1)
	}
	defer fb.Close(ctx)

	cfg := platform.SoapyConfig{
		Driver:       "simulated",
		Device:       "dummy",
		CenterFreqHz: 100e6,
		Simulated:    true,
		BackendConfig: output.BackendConfig{
			SampleRateHz: 238_000,
			Channels:     2,
			IQLevel:      1.0,
			Metadata:     map[string]string{"example": "soapy-sim"},
		},
	}

	driver := platform.NewSimulatedDriver(fb)
	backend := platform.NewSoapyBackend(cfg, driver)

	if err := backend.Configure(ctx, cfg.BackendConfig); err != nil {
		fmt.Fprintf(os.Stderr, "backend configure: %v\n", err)
		os.Exit(1)
	}

	frame := &output.CompositeFrame{
		SampleRateHz: cfg.BackendConfig.SampleRateHz,
		Timestamp:    time.Now(),
		Samples:      make([]output.IQSample, 512),
	}

	for idx := range frame.Samples {
		val := float32((idx%64))/32 - 1
		frame.Samples[idx].I = val
		frame.Samples[idx].Q = -val
	}

	written, err := backend.Write(ctx, frame)
	if err != nil {
		fmt.Fprintf(os.Stderr, "write frame: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("wrote %d samples to simulated Soapy backend\n", written)

	if err := backend.Flush(ctx); err != nil {
		fmt.Fprintf(os.Stderr, "flush: %v\n", err)
	}
}