attempt to reduce cpu usage by pre-selecting parts of the spectrum with
resamplers
This commit is contained in:
Jakob Ketterl
@@ -1,9 +1,11 @@
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import threading
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import socket
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from owrx.source import SdrService
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from owrx.bands import Bandplan
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from csdr import dsp, output
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from owrx.wsjt import WsjtParser
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from owrx.config import PropertyManager
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from owrx.source import Resampler
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import logging
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@@ -63,28 +65,110 @@ class ServiceHandler(object):
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self.startupTimer = threading.Timer(10, self.updateServices)
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self.startupTimer.start()
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def getAvailablePort(self):
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s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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s.bind(("", 0))
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s.listen(1)
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port = s.getsockname()[1]
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s.close()
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return port
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def updateServices(self):
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logger.debug("re-scheduling services due to sdr changes")
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self.stopServices()
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cf = self.source.getProps()["center_freq"]
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srh = self.source.getProps()["samp_rate"] / 2
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sr = self.source.getProps()["samp_rate"]
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srh = sr / 2
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frequency_range = (cf - srh, cf + srh)
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self.services = [
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self.setupService(dial["mode"], dial["frequency"])
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dials = [
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dial
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for dial in Bandplan.getSharedInstance().collectDialFrequencies(frequency_range)
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if self.isSupported(dial["mode"])
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]
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def setupService(self, mode, frequency):
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if not dials:
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logger.debug("no services available")
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return
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self.services = []
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for group in self.optimizeResampling(dials, sr):
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frequencies = sorted([f["frequency"] for f in group])
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min = frequencies[0]
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max = frequencies[-1]
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cf = (min + max) / 2
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bw = max - min
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logger.debug("group center frequency: {0}, bandwidth: {1}".format(cf, bw))
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resampler_props = PropertyManager()
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resampler_props["center_freq"] = cf
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# TODO the + 24000 is a temporary fix since the resampling optimizer does not account for required bandwidths
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resampler_props["samp_rate"] = bw + 24000
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resampler = Resampler(resampler_props, self.getAvailablePort(), self.source)
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resampler.start()
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self.services.append(resampler)
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for dial in group:
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self.services.append(self.setupService(dial["mode"], dial["frequency"], resampler))
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def optimizeResampling(self, freqs, bandwidth):
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freqs = sorted(freqs, key=lambda f: f["frequency"])
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distances = [{
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"frequency": freqs[i]["frequency"],
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"distance": freqs[i+1]["frequency"] - freqs[i]["frequency"],
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} for i in range(0, len(freqs)-1)]
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distances = [d for d in distances if d["distance"] > 0]
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distances = sorted(distances, key=lambda f: f["distance"], reverse=True)
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def calculate_usage(num_splits):
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splits = sorted([f["frequency"] for f in distances[0:num_splits]])
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previous = 0
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groups = []
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for split in splits:
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groups.append([f for f in freqs if previous < f["frequency"] <= split])
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previous = split
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groups.append([f for f in freqs if previous < f["frequency"]])
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def get_bandwitdh(group):
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freqs = sorted([f["frequency"] for f in group])
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# the group will process the full BW once, plus the reduced BW once for each group member
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return bandwidth + len(group) * (freqs[-1] - freqs[0] + 24000)
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total_bandwidth = sum([get_bandwitdh(group) for group in groups])
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return {
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"num_splits": num_splits,
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"total_bandwidth": total_bandwidth,
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"groups": groups,
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}
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usages = [calculate_usage(i) for i in range(0, len(freqs))]
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# this is simulating no resampling. i haven't seen this as the best result yet
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usages += [{
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"num_splits": None,
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"total_bandwidth": bandwidth * len(freqs),
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"groups": [freqs]
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}]
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results = sorted(usages, key=lambda f: f["total_bandwidth"])
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for r in results:
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logger.debug("splits: {0}, total: {1}".format(r["num_splits"], r["total_bandwidth"]))
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return results[0]["groups"]
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def setupService(self, mode, frequency, source):
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logger.debug("setting up service {0} on frequency {1}".format(mode, frequency))
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d = dsp(ServiceOutput(frequency))
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d.nc_port = self.source.getPort()
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d.set_offset_freq(frequency - self.source.getProps()["center_freq"])
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d.nc_port = source.getPort()
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d.set_offset_freq(frequency - source.getProps()["center_freq"])
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d.set_demodulator("usb")
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d.set_bpf(0, 3000)
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d.set_secondary_demodulator(mode)
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d.set_audio_compression("none")
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d.set_samp_rate(self.source.getProps()["samp_rate"])
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d.set_samp_rate(source.getProps()["samp_rate"])
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d.start()
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return d
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@@ -274,6 +274,93 @@ class SdrSource(object):
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c.write_spectrum_data(data)
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class Resampler(SdrSource):
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def __init__(self, props, port, sdr):
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sdrProps = sdr.getProps()
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self.shift = (sdrProps["center_freq"] - props["center_freq"]) / sdrProps["samp_rate"]
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self.decimation = int(float(sdrProps["samp_rate"]) / props["samp_rate"])
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if_samp_rate = sdrProps["samp_rate"] / self.decimation
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self.transition_bw = 0.15 * (if_samp_rate / float(sdrProps["samp_rate"]))
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props["samp_rate"] = if_samp_rate
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self.sdr = sdr
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super().__init__(props, port)
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def start(self):
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self.modificationLock.acquire()
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if self.monitor:
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self.modificationLock.release()
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return
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props = self.rtlProps
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resampler_command = [
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"nc -v 127.0.0.1 {nc_port}".format(nc_port=self.sdr.getPort()),
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"csdr shift_addition_cc {shift}".format(shift=self.shift),
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"csdr fir_decimate_cc {decimation} {ddc_transition_bw} HAMMING".format(
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decimation=self.decimation,
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ddc_transition_bw=self.transition_bw,
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),
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]
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nmux_bufcnt = nmux_bufsize = 0
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while nmux_bufsize < props["samp_rate"] / 4:
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nmux_bufsize += 4096
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while nmux_bufsize * nmux_bufcnt < props["nmux_memory"] * 1e6:
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nmux_bufcnt += 1
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if nmux_bufcnt == 0 or nmux_bufsize == 0:
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logger.error(
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"Error: nmux_bufsize or nmux_bufcnt is zero. These depend on nmux_memory and samp_rate options in config_webrx.py"
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)
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self.modificationLock.release()
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return
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logger.debug("nmux_bufsize = %d, nmux_bufcnt = %d" % (nmux_bufsize, nmux_bufcnt))
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resampler_command += ["nmux --bufsize %d --bufcnt %d --port %d --address 127.0.0.1" % (
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nmux_bufsize,
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nmux_bufcnt,
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self.port,
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)]
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cmd = " | ".join(resampler_command)
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logger.debug("resampler command: %s", cmd)
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self.process = subprocess.Popen(cmd, shell=True, preexec_fn=os.setpgrp)
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logger.info("Started resampler source: " + cmd)
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available = False
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def wait_for_process_to_end():
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rc = self.process.wait()
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logger.debug("shut down with RC={0}".format(rc))
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self.monitor = None
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self.monitor = threading.Thread(target=wait_for_process_to_end)
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self.monitor.start()
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retries = 1000
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while retries > 0:
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retries -= 1
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if self.monitor is None:
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break
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testsock = socket.socket()
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try:
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testsock.connect(("127.0.0.1", self.getPort()))
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testsock.close()
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available = True
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break
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except:
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time.sleep(0.1)
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self.modificationLock.release()
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if not available:
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raise SdrSourceException("resampler source failed to start up")
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for c in self.clients:
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c.onSdrAvailable()
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def activateProfile(self, profile_id=None):
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pass
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class RtlSdrSource(SdrSource):
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def getCommand(self):
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return "rtl_sdr -s {samp_rate} -f {center_freq} -p {ppm} -g {rf_gain} -"
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