Re: Discuss-gnuradio Digest, Vol 207, Issue 21

[Faisal Khan]

hye i am new to gnu radio

i want guidance about that while receiving two channels how can i separate those channels and records their audio in their respective files simultaneously..

On Mon, Jan 20, 2020 at 10:02 PM <address@hidden> wrote:

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Today's Topics:

   1. GR 3.8 overflow, dropped samples with 2 channels from B210
      (Michael Wentz)
   2. Constellation script (michel slepoukha)


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Message: 1
Date: Sun, 19 Jan 2020 14:02:36 -0500
From: Michael Wentz <address@hidden>
To: address@hidden
Subject: GR 3.8 overflow, dropped samples with 2 channels from B210
Message-ID:
        <CAFTrPL0dTCy-B5t-m2M=address@hidden>
Content-Type: text/plain; charset="utf-8"

Hi,

I recently updated to GNU Radio 3.8 and noticed some code that receives 2
channels from a B210 is now always printing a single overflow (O) followed
by two drops (DD) right after the flowgraph starts. This happens regardless
of the sample rate and only when using 2 channels. It also doesn't happen
outside of GNU Radio; the UHD examples benchmark_rate and rx_multi_samples
never show overflows or drops. I've tested under macOS 10.14 and RHEL 7,
both with UHD 3.15. I also tried downgrading to GNU Radio to 3.7.13.5 and
problem goes away, so it seems like a GR issue and not UHD.

In debugging with a file meta sink I've found that the first header for
both channels always shows 38760 items before it gets a new tag. I did some
more testing with a very simple flowgraph of just a USRP source and null
sink. With 1 channel I can stream 20 MSPS without problems. With 2 channels
I tried rates 250 KSPS to 4 MSPS and saw the same behavior every time.

I thought that maybe the device was starting to stream before the flowgraph
was ready, so tried setting a start time several seconds in the future, but
that didn't make a difference. I also tried resetting the B210 and the host
USB subsystem.

Any idea what could be going on? A snippet of how the 2 channel B210 is set
up by GRC is below.

Thanks,
Michael

---

self.uhd_usrp_source_0 = uhd.usrp_source(
            ",".join(("", "")),
            uhd.stream_args(
                cpu_format="sc16",
                args='',
                channels=[0,1],
            ),
        )
        self.uhd_usrp_source_0.set_center_freq(1e9, 0)
        self.uhd_usrp_source_0.set_gain(0, 0)
        self.uhd_usrp_source_0.set_antenna('RX2', 0)
        self.uhd_usrp_source_0.set_center_freq(0, 1)
        self.uhd_usrp_source_0.set_gain(0, 1)
        self.uhd_usrp_source_0.set_antenna('RX2', 1)
        self.uhd_usrp_source_0.set_samp_rate(1e6)
        self.uhd_usrp_source_0.set_time_unknown_pps(uhd.time_spec())
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Message: 2
Date: Mon, 20 Jan 2020 17:41:18 +0100
From: michel slepoukha <address@hidden>
To: address@hidden
Subject: Constellation script
Message-ID: <address@hidden>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

Hello all!
I designed in 2018 the DMR-C4FM relay from Albi (Tarn), F5ZLH
it works…
Well, not that good, because we noticed  a poor signal quality:


with the constellation, on a portable equipment such as the Rpi 4. we
will beable to adjust the relay settings
And there only GNURadio is installed correctly and worked perfectly with
an RTL-SDR key.
But most of the flow chart examples use logical signal sources and if
some of them have an RTL-SDR key as input, they are either incomplete or
with errors (wonder if this is not done expressly?) . And above all, no
script linked to the flow chart concerned.
So, I can only turn to the competence of your team to finally have this
script validated.
Configuration is simple: SDR-RTL → constellation
With thanks for help
Mike

--
   Michel SLEPOUKHA     F5ZZ
    (FR5FI - TU2DD - 6W8IY)
      F5ZZ-10  JN13AV


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