Increase sample Rate

Philipp

With the following code I can reach sampling rates between 65-78 kHz (depending on the size of the data array). Is it possible to increase the sampling rate?

from artiq.experiment import *
import numpy as np

class SamplerTest(EnvExperiment):
    kernel_invariants = {"numberOfSamples","samplingPeriod"}

    def build(self):
        self.setattr_device("core")
        self.setattr_device("sampler0")
        self.setattr_argument("samplingDuration", NumberValue(ndecimals=3, step=1, default=1, scale=s, unit="s"))
        self.setattr_argument("samplingRate", NumberValue(ndecimals=3, step=10, default=40, scale=Hz, unit="Hz"))

    def prepare(self):
        self.numberOfSamples = int(self.samplingRate * self.samplingDuration)
        self.samplingPeriod = 1 / self.samplingRate
        self.data = np.full((self.numberOfSamples,8),0,dtype=np.int32)

    @kernel
    def run(self):
        self.core.reset()
        self.core.break_realtime()
        
        self.sampler0.init()
        delay(100*us)

        self.getSamples()

    @kernel
    def getSamples(self):
        for i in range(self.numberOfSamples):
            with parallel:
                self.sampler0.sample_mu(self.data[i])
                delay(self.samplingPeriod)

sb10q

Not with currently available code, which can be improved (e.g. implement DMA-IN) but requires funding. Kasli-SoC with Zynq, by itself, would not help much here since the high latency of the AXI bus kills RTIO performance.

rjo

Another approach would be to develop a Sampler PHY that does autonomous fixed-schedule sampling and then feeds a configurable burst into RTIO-input. But that might be factor of two or three in sustained throughput. Higher would require DMA-input or different ways of in-gateware processing of the samples (like SU-Servo).