attempt to reduce cpu usage by pre-selecting parts of the spectrum with

resamplers
2019-09-11 00:30:14 +02:00
parent 6d44aa3f58
commit d87e5da75c
2 changed files with 178 additions and 7 deletions
--- a/owrx/source.py
+++ b/owrx/source.py
@ -274,6 +274,93 @@ class SdrSource(object):
            c.write_spectrum_data(data)


+class Resampler(SdrSource):
+    def __init__(self, props, port, sdr):
+        sdrProps = sdr.getProps()
+        self.shift = (sdrProps["center_freq"] - props["center_freq"]) / sdrProps["samp_rate"]
+        self.decimation = int(float(sdrProps["samp_rate"]) / props["samp_rate"])
+        if_samp_rate = sdrProps["samp_rate"] / self.decimation
+        self.transition_bw = 0.15 * (if_samp_rate / float(sdrProps["samp_rate"]))
+        props["samp_rate"] = if_samp_rate
+
+        self.sdr = sdr
+        super().__init__(props, port)
+
+    def start(self):
+        self.modificationLock.acquire()
+        if self.monitor:
+            self.modificationLock.release()
+            return
+
+        props = self.rtlProps
+
+        resampler_command = [
+            "nc -v 127.0.0.1 {nc_port}".format(nc_port=self.sdr.getPort()),
+            "csdr shift_addition_cc {shift}".format(shift=self.shift),
+            "csdr fir_decimate_cc {decimation} {ddc_transition_bw} HAMMING".format(
+                decimation=self.decimation,
+                ddc_transition_bw=self.transition_bw,
+            ),
+        ]
+
+        nmux_bufcnt = nmux_bufsize = 0
+        while nmux_bufsize < props["samp_rate"] / 4:
+            nmux_bufsize += 4096
+        while nmux_bufsize * nmux_bufcnt < props["nmux_memory"] * 1e6:
+            nmux_bufcnt += 1
+        if nmux_bufcnt == 0 or nmux_bufsize == 0:
+            logger.error(
+                "Error: nmux_bufsize or nmux_bufcnt is zero. These depend on nmux_memory and samp_rate options in config_webrx.py"
+            )
+            self.modificationLock.release()
+            return
+        logger.debug("nmux_bufsize = %d, nmux_bufcnt = %d" % (nmux_bufsize, nmux_bufcnt))
+        resampler_command += ["nmux --bufsize %d --bufcnt %d --port %d --address 127.0.0.1" % (
+            nmux_bufsize,
+            nmux_bufcnt,
+            self.port,
+        )]
+        cmd = " | ".join(resampler_command)
+        logger.debug("resampler command: %s", cmd)
+        self.process = subprocess.Popen(cmd, shell=True, preexec_fn=os.setpgrp)
+        logger.info("Started resampler source: " + cmd)
+
+        available = False
+
+        def wait_for_process_to_end():
+            rc = self.process.wait()
+            logger.debug("shut down with RC={0}".format(rc))
+            self.monitor = None
+
+        self.monitor = threading.Thread(target=wait_for_process_to_end)
+        self.monitor.start()
+
+        retries = 1000
+        while retries > 0:
+            retries -= 1
+            if self.monitor is None:
+                break
+            testsock = socket.socket()
+            try:
+                testsock.connect(("127.0.0.1", self.getPort()))
+                testsock.close()
+                available = True
+                break
+            except:
+                time.sleep(0.1)
+
+        self.modificationLock.release()
+
+        if not available:
+            raise SdrSourceException("resampler source failed to start up")
+
+        for c in self.clients:
+            c.onSdrAvailable()
+
+    def activateProfile(self, profile_id=None):
+        pass
+
+
 class RtlSdrSource(SdrSource):
    def getCommand(self):
        return "rtl_sdr -s {samp_rate} -f {center_freq} -p {ppm} -g {rf_gain} -"