updates

1 files changed, 84 insertions, 0 deletions

diff --git a/lora/stuff.go b/lora/stuff.go
new file mode 100644
index 0000000..1cee21a
--- /dev/null
+++ b/lora/stuff.go
@@ -0,0 +1,84 @@
+// Package loraradio provides functionality to determine values for a LoRa radio link,
+// including maximum data rate and link budget while accounting for receiver sensitivity.
+package lora
+
+import (
+	"fmt"
+	"math"
+)
+
+// TODO: needs cleanup. lots of gpt generated code
+
+// MaxDataRate calculates the maximum data rate for a LoRa radio link based on the provided parameters.
+func MaxDataRate(bandwidth, spreadingFactor, codeRate float64) float64 {
+	// Assuming the LoRa modulation's data rate equation:
+	// Data Rate = BW / (2^SF) * CR
+	// where SF is the spreading factor, BW is the bandwidth in Hz, and CR is the code rate.
+	return (bandwidth / math.Pow(2, spreadingFactor)) * codeRate * spreadingFactor
+}
+
+// Simplified link budget calculation per the Semtech calculator
+func LinkBudget(rxSensitivity, transmitPower float64) float64 {
+	return transmitPower - rxSensitivity
+}
+
+// SensitivityParams holds the parameters used for sensitivity calculations.
+type SensitivityParams struct {
+	Bandwidth       float64 // in Hz
+	ImplementationL float64 // Implementation loss in dB, typically 1-3 dB
+	SpreadingFactor int     // LoRa Spreading Factor
+}
+
+// SpreadingFactorData holds the data for each spreading factor.
+type SpreadingFactorData struct {
+	SF             int
+	ChipsPerSymbol int
+	DemodulatorSNR float64
+}
+
+var SpreadingFactors = []SpreadingFactorData{
+	{SF: 5, ChipsPerSymbol: 32, DemodulatorSNR: -2.5},
+	{SF: 6, ChipsPerSymbol: 64, DemodulatorSNR: -5},
+	{SF: 7, ChipsPerSymbol: 128, DemodulatorSNR: -7.5},
+	{SF: 8, ChipsPerSymbol: 256, DemodulatorSNR: -10},
+	{SF: 9, ChipsPerSymbol: 512, DemodulatorSNR: -12.5},
+	{SF: 10, ChipsPerSymbol: 1024, DemodulatorSNR: -15},
+	{SF: 11, ChipsPerSymbol: 2048, DemodulatorSNR: -17.5},
+	{SF: 12, ChipsPerSymbol: 4096, DemodulatorSNR: -20},
+}
+
+// CalculateSensitivity calculates the LoRa receiver sensitivity based on the provided parameters.
+func CalculateSensitivity(params SensitivityParams, spreadingFactors []SpreadingFactorData) (float64, error) {
+	if params.Bandwidth <= 0 {
+		return 0, fmt.Errorf("bandwidth must be greater than 0")
+	}
+
+	// Find the SNR for the given spreading factor from the provided data.
+	var snr float64
+	found := false
+	for _, sfData := range spreadingFactors {
+		if sfData.SF == params.SpreadingFactor {
+			snr = sfData.DemodulatorSNR
+			found = true
+			break
+		}
+	}
+	if !found {
+		return 0, fmt.Errorf("spreading factor data not found for SF=%d", params.SpreadingFactor)
+	}
+
+	// Thermal noise in dBm for the given bandwidth at room temperature (290K).
+	thermalNoise := -174.0 // dBm/Hz
+
+	// Noise figure in dBm for the given bandwidth.
+	noiseFigure := thermalNoise + 10*math.Log10(params.Bandwidth)
+
+	// Receiver sensitivity calculation in dBm.
+	sensitivity := noiseFigure + snr + params.ImplementationL
+
+	return sensitivity, nil
+}
+func SNR(spreadingFactor int) float64 {
+	result := (float64(spreadingFactor) - 4) * -2.5
+	return result * 100 / 100
+}