Remove decimation functionality.

Builds produced on go1.9.2 and above are efficient enough on RPi3 and friends to
make the decimation functionality obsolete.

README.md

@@ -26,7 +26,6 @@ Available command-line flags are as follows:
 
 ```
 Usage of rtlamr:
-  -decimation=1: integer decimation factor, keep every nth sample
   -duration=0s: time to run for, 0 for infinite, ex. 1h5m10s
   -filterid=: display only messages matching an id in a comma-separated list of ids.
   -filtertype=: display only messages matching a type in a comma-separated list of types.

decode/decode.go

@@ -39,46 +39,7 @@ type PacketConfig struct {
 	CenterFreq uint32
 }
 
-func (cfg PacketConfig) Decimate(decimation int) PacketConfig {
-	cfg.BlockSize /= decimation
-	cfg.BlockSize2 /= decimation
-	cfg.ChipLength /= decimation
-	cfg.SymbolLength /= decimation
-	cfg.SampleRate /= decimation
-	cfg.DataRate /= decimation
-
-	cfg.PreambleLength /= decimation
-	cfg.PacketLength /= decimation
-
-	cfg.BufferLength /= decimation
-
-	return cfg
-}
-
 func (d Decoder) Log() {
-	if d.Decimation != 1 {
-		log.Printf("BlockSize: %d|%d\n", d.Cfg.BlockSize, d.DecCfg.BlockSize)
-		log.Println("CenterFreq:", d.Cfg.CenterFreq)
-		log.Printf("SampleRate: %d|%d\n", d.Cfg.SampleRate, d.DecCfg.SampleRate)
-		log.Printf("DataRate: %d|%d\n", d.Cfg.DataRate, d.DecCfg.DataRate)
-		log.Printf("ChipLength: %d|%d\n", d.Cfg.ChipLength, d.DecCfg.ChipLength)
-		log.Println("PreambleSymbols:", d.Cfg.PreambleSymbols)
-		log.Printf("PreambleLength: %d|%d\n", d.Cfg.PreambleLength, d.DecCfg.PreambleLength)
-		log.Println("PacketSymbols:", d.Cfg.PacketSymbols)
-		log.Printf("PacketLength: %d|%d\n", d.Cfg.PacketLength, d.DecCfg.PacketLength)
-		log.Println("Preamble:", d.Cfg.Preamble)
-
-		if d.Cfg.ChipLength%d.Decimation != 0 {
-			log.Println("Warning: decimated symbol length is non-integral, sensitivity may be poor")
-		}
-
-		if d.DecCfg.ChipLength < 3 {
-			log.Fatal("Error: illegal decimation factor, choose a smaller factor")
-		}
-
-		return
-	}
-
 	log.Println("CenterFreq:", d.Cfg.CenterFreq)
 	log.Println("SampleRate:", d.Cfg.SampleRate)
 	log.Println("DataRate:", d.Cfg.DataRate)
@@ -94,8 +55,7 @@ func (d Decoder) Log() {
 type Decoder struct {
 	Cfg PacketConfig
 
-	Decimation int
-	DecCfg     PacketConfig
+	DecCfg PacketConfig
 
 	Signal    []float64
 	Filtered  []float64
@@ -113,7 +73,7 @@ type Decoder struct {
 }
 
 // Create a new decoder with the given packet configuration.
-func NewDecoder(cfg PacketConfig, decimation int) (d Decoder) {
+func NewDecoder(cfg PacketConfig) (d Decoder) {
 	d.Cfg = cfg
 
 	d.Cfg.SymbolLength = d.Cfg.ChipLength << 1
@@ -127,9 +87,6 @@ func NewDecoder(cfg PacketConfig, decimation int) (d Decoder) {
 
 	d.Cfg.BufferLength = d.Cfg.PacketLength + d.Cfg.BlockSize
 
-	d.Decimation = decimation
-	d.DecCfg = d.Cfg.Decimate(d.Decimation)
-
 	// Allocate necessary buffers.
 	d.Signal = make([]float64, d.DecCfg.BlockSize+d.DecCfg.SymbolLength)
 	d.Filtered = make([]float64, d.DecCfg.BlockSize)

flags.go

@@ -38,8 +38,6 @@ var msgType = flag.String("msgtype", "scm", "message type to receive: scm, scm+,
 
 var symbolLength = flag.Int("symbollength", 72, "symbol length in samples")
 
-var decimation = flag.Int("decimation", 1, "integer decimation factor, keep every nth sample")
-
 var timeLimit = flag.Duration("duration", 0, "time to run for, 0 for infinite, ex. 1h5m10s")
 var meterID MeterIDFilter
 var meterType MeterTypeFilter
@@ -64,7 +62,6 @@ func RegisterFlags() {
 		"samplefile":   true,
 		"msgtype":      true,
 		"symbollength": true,
-		"decimation":   true,
 		"duration":     true,
 		"filterid":     true,
 		"filtertype":   true,

idm/idm.go

@@ -55,9 +55,9 @@ func (p *Parser) Cfg() *decode.PacketConfig {
 	return &p.Decoder.Cfg
 }
 
-func NewParser(chipLength, decimation int) (p parse.Parser) {
+func NewParser(chipLength int) (p parse.Parser) {
 	return &Parser{
-		decode.NewDecoder(NewPacketConfig(chipLength), decimation),
+		decode.NewDecoder(NewPacketConfig(chipLength)),
 		crc.NewCRC("CCITT", 0xFFFF, 0x1021, 0x1D0F),
 	}
 }

main.go

@@ -50,7 +50,7 @@ type Receiver struct {
 
 func (rcvr *Receiver) NewReceiver() {
 	var err error
-	if rcvr.p, err = parse.NewParser(strings.ToLower(*msgType), *symbolLength, *decimation); err != nil {
+	if rcvr.p, err = parse.NewParser(strings.ToLower(*msgType), *symbolLength); err != nil {
 		log.Fatal(err)
 	}
 

parse/parse.go

@@ -20,7 +20,7 @@ var (
 	parsers     = make(map[string]NewParserFunc)
 )
 
-type NewParserFunc func(symbolLength, decimation int) Parser
+type NewParserFunc func(symbolLength int) Parser
 
 func Register(name string, parserFn NewParserFunc) {
 	parserMutex.Lock()
@@ -35,12 +35,12 @@ func Register(name string, parserFn NewParserFunc) {
 	parsers[name] = parserFn
 }
 
-func NewParser(name string, symbolLength, decimation int) (Parser, error) {
+func NewParser(name string, symbolLength int) (Parser, error) {
 	parserMutex.Lock()
 	defer parserMutex.Unlock()
 
 	if parserFn, exists := parsers[name]; exists {
-		return parserFn(symbolLength, decimation), nil
+		return parserFn(symbolLength), nil
 	} else {
 		return nil, fmt.Errorf("invalid message type: %q\n", name)
 	}

r900/r900.go

@@ -57,10 +57,10 @@ type Parser struct {
 	quantized []byte
 }
 
-func NewParser(chipLength, decimation int) parse.Parser {
+func NewParser(chipLength int) parse.Parser {
 	p := new(Parser)
 
-	p.Decoder = decode.NewDecoder(NewPacketConfig(chipLength), decimation)
+	p.Decoder = decode.NewDecoder(NewPacketConfig(chipLength))
 
 	// GF of order 32, polynomial 37, generator 2.
 	p.field = gf.NewField(32, 37, 2)

r900bcd/r900bcd.go

@@ -31,8 +31,8 @@ type Parser struct {
 	parse.Parser
 }
 
-func NewParser(ChipLength, decimation int) parse.Parser {
-	return Parser{r900.NewParser(ChipLength, decimation)}
+func NewParser(ChipLength int) parse.Parser {
+	return Parser{r900.NewParser(ChipLength)}
 }
 
 // Parse messages using r900 parser and convert consumption from BCD to int.

scm/scm.go

@@ -46,9 +46,9 @@ type Parser struct {
 	crc.CRC
 }
 
-func NewParser(chipLength, decimation int) (p parse.Parser) {
+func NewParser(chipLength int) (p parse.Parser) {
 	return &Parser{
-		decode.NewDecoder(NewPacketConfig(chipLength), decimation),
+		decode.NewDecoder(NewPacketConfig(chipLength)),
 		crc.NewCRC("BCH", 0, 0x6F63, 0),
 	}
 }

scmplus/scmplus.go

@@ -55,9 +55,9 @@ func (p *Parser) Cfg() *decode.PacketConfig {
 	return &p.Decoder.Cfg
 }
 
-func NewParser(chipLength, decimation int) (p parse.Parser) {
+func NewParser(chipLength int) (p parse.Parser) {
 	return &Parser{
-		decode.NewDecoder(NewPacketConfig(chipLength), decimation),
+		decode.NewDecoder(NewPacketConfig(chipLength)),
 		crc.NewCRC("CCITT", 0xFFFF, 0x1021, 0x1D0F),
 	}
 }