func nearestGain(dev *rtl.Context, targetGain int) (nearest int, err error) {
err = dev.SetTunerGainMode(true)
if err != nil {
return
}
gains, err := dev.GetTunerGains()
if err != nil {
return
}
if len(gains) == 0 {
err = fmt.Errorf("No gains returned")
return
}
nearest = gains[0]
for i := 0; i < len(gains); i++ {
res1 := math.Abs(float64(targetGain - nearest))
res2 := math.Abs(float64(targetGain - gains[i]))
if res2 < res1 {
nearest = gains[i]
}
}
return
}
func main() {
runtime.GOMAXPROCS(3)
var status int
var dev *rtl.Context
if c := rtl.GetDeviceCount(); c == 0 {
log.Fatal("No devices found, exiting.\n")
} else {
for i := 0; i < c; i++ {
m, p, s, status := rtl.GetDeviceUsbStrings(i)
log.Printf("GetDeviceUsbStrings %s - %s %s %s\n",
rtl.Status[status], m, p, s)
}
}
log.Printf("===== Device name: %s =====\n", rtl.GetDeviceName(0))
log.Printf("===== Running tests using device indx: %d =====\n", 0)
if dev, status = rtl.Open(0); status != rtl.Success {
log.Fatal("\tOpen Failed, exiting\n")
}
defer dev.Close()
go sig_abort(dev)
m, p, s, status := dev.GetUsbStrings()
log.Printf("\tGetUsbStrings %s - %s %s %s\n", rtl.Status[status], m, p, s)
g, status := dev.GetTunerGains()
log.Printf("\tGetTunerGains %s\n", rtl.Status[status])
if status == rtl.Success {
fmt.Printf("\tGains: ")
for _, j := range g {
fmt.Printf("%d ", j)
}
fmt.Printf("\n")
}
log.Printf("\tSetSampleRate %s - rate: %d\n",
rtl.Status[dev.SetSampleRate(rtl.DefaultSampleRate)], rtl.DefaultSampleRate)
log.Printf("\tGetSampleRate: %d\n", dev.GetSampleRate())
// status = dev.SetXtalFreq(rtl_freq, tuner_freq)
// log.Printf("\tSetXtalFreq %s - Center freq: %d, Tuner freq: %d\n",
// rtl.Status[status], rtl_freq, tuner_freq)
rtl_freq, tuner_freq, status := dev.GetXtalFreq()
log.Printf("\tGetXtalFreq %s - Rtl: %d, Tuner: %d\n",
rtl.Status[status], rtl_freq, tuner_freq)
status = dev.SetCenterFreq(850000000)
if status < 0 {
log.Println("\tSetCenterFreq 850MHz Failed, error code: %d\n", status)
} else {
log.Println("\tSetCenterFreq 850MHz Successful")
}
log.Printf("\tGetCenterFreq: %d\n", dev.GetCenterFreq())
log.Printf("\tGetFreqCorrection: %d\n", dev.GetFreqCorrection())
log.Printf("\tGetTunerType: %s\n", rtl.TunerType[dev.GetTunerType()])
log.Printf("\tSetTunerGainMode: %s\n", rtl.TunerType[dev.SetTunerGainMode(rtl.GainAuto)])
log.Printf("\tGetTunerGain: %d\n", dev.GetTunerGain())
/*
func (c *Context) SetFreqCorrection(ppm int) (err int)
func (c *Context) SetTunerGain(gain int) (err int)
func (c *Context) SetTunerIfGain(stage, gain int) (err int)
func (c *Context) SetAgcMode(on int) (err int)
func (c *Context) SetDirectSampling(on int) (err int)
*/
if status = dev.SetTestMode(1); status < 1 {
log.Printf("\tSetTestMode 'On' Failed - error code: %d\n", status)
} else {
log.Printf("\tSetTestMode 'On' Successful\n")
}
log.Printf("\tResetBuffer %s\n", rtl.Status[dev.ResetBuffer()])
var buffer []byte = make([]uint8, rtl.DefaultBufLength)
n_read, status := dev.ReadSync(buffer, rtl.DefaultBufLength)
log.Printf("\tReadSync %s\n", rtl.Status[status])
if status == rtl.Success && n_read < rtl.DefaultBufLength {
log.Println("ReadSync short read, %d samples lost\n", rtl.DefaultBufLength-n_read)
}
if status = dev.SetTestMode(1); status < 1 {
log.Printf("\tSetTestMode 'Off' Fail - error code: %d\n", status)
} else {
log.Printf("\tSetTestMode 'Off' Success\n")
}
// Note, ReadAsync blocks until CancelAsync is called, so spawn
// a goroutine running in its own system thread that'll wait
// for the async-read callback to signal when it's done.
IQch := make(chan bool)
go async_stop(dev, IQch)
var userctx rtl.UserCtx = IQch
status = dev.ReadAsync(rtlsdr_cb, &userctx, rtl.DefaultAsyncBufNumber, rtl.DefaultBufLength)
log.Printf("\tReadAsync %s\n", rtl.Status[status])
log.Printf("Exiting...\n")
}