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seeking a supplemental, simple audio recorder for KiwiSDR Ubuntu

Discussion in 'Software Defined Radio (SDR)' started by N2LKR, Apr 29, 2019.

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  1. N2LKR

    N2LKR Ham Member QRZ Page

    Hi,

    I've recently become quite interested in online SDR's, particularly the KiwiSDR receivers. Although the software itself does have a record option, I find it lacking, especially when suddenly getting cut off and losing an hour or more of a recording, etc, and therefore I am looking for a better recorder. My OS is Ubuntu.

    When I did initial searching, I found a program called Kiwirecorder, but I have found attempted installation impossible so far and I also would prefer something more GUI based. Also, I'm not interested in capturing IQ that KiwiSDR offers, only 16 bit WAV or higher audio recordings without interruptions.

    I've been told that certain audio editors can perform this task. I have Audacity installed on my OS, but unable to capture anything so far.

    Just want to keep things simple....

    Thanks in advance,
    Eric
     
  2. G0GSR

    G0GSR Ham Member QRZ Page

    Hi Eric.
    I use Audacity every day for this.
    Make sure you have "Pulse audio volume control" installed. Start Audacity recording, go the Pulse Audio volume control and you will see what apps are recording. You can then use it to switch the Audacity app to record from "Monitor of built-in audio" (or similar dependant on your hardware.).

    If you don't have the device "Monitor of (audio device)" then right click on the systray speaker icon, (opens Audio volume settings). Select "Audio volume" - Advanced tab and enable "Add virtual output device for simultaneous output......."

    Frank
     
  3. N2LKR

    N2LKR Ham Member QRZ Page

    Hi Frank,
    Thanks for your quick response! I thought Audacity might be able to do this. I do see the options for pulse audio in the program, but I don't know if that means it's installed. When I search for pulseaudio in the apps, it's not coming up. I am on 16.04. What should I write in terminal to check for sure and can you recommend a site with installation instructions?
    Thanks,
    Eric
     
  4. N2LKR

    N2LKR Ham Member QRZ Page

    Hello again Frank,

    I got it. I was just missing the volume control, but now it's installed and Audacity is doing the job! Thanks again for the info. Now I only wish I could find a way to bypass some of the time limitations of the SDR's lol.

    Eric
     
  5. G0GSR

    G0GSR Ham Member QRZ Page

    Glad you have it sorted.
    Rationing Eric.... So annoying. I was allowed 30 minutes, then banned for 24 hours yesterday. That's no use to anyone.
    Frank
     
    Last edited: Apr 30, 2019
  6. N2LKR

    N2LKR Ham Member QRZ Page

    Hi Frank,

    If only I could have ever figured out how to get the Kiwirecorder installed correctly on Ubuntu 16.04, I would share that knowledge as you and I could bypass such limitations. As it is, I think I spoke a bit too soon yesterday: after trying to record something for a couple of hours, I came in to find that I still heard audio, but my entire OS was frozen and I had to reboot! I notice that my main desktop has been doing this more and more when trying to record SDR so not sure what to make of it. I use Firefox as browser. With Firefox, KiwiSDR at a station, pulse audio and Audacity recording, the freeze occurred unexpectedly. I notice that if I keep recordings less than 15 min or so in Audacity, I haven't had a freeze so far, plus I am now trying my standby browser Tor. My desktop has an SSD drive too.

    Now the laptop I use as a substitute only has the KiwiSDR recording and I seem to be able to for many hours on sites where there are no restrictions. It also has Ubuntu 16.04, but only 4 GB memory (unlike the desktop which has 8 GB), and a standard HDD. I had to laugh as it really really had a "hic up" yesterday after stopping the KiwiSDR recording after 10 hours, but after a few minutes it gave me the chance to save the nearly 1 GB file. Don't know why this slower machine seems to be fairing better.

    One good thing about Audacity is that one can specify high quality modes, such as 32 bit float record, which can make a fairly significant difference when applying noise reduction later over standard 16 bit... that is, when I don't get the freezes.

    Eric
     
  7. G0GSR

    G0GSR Ham Member QRZ Page

    Hi Eric.
    Sorry to hear about the "freezes" that could be literally anything.
    Why not open up a terminal and type "top". That will give you a live view of how much memory and CPU time each process is using.
    Keep any eye open for things hogging CPU and memory, see if you can narrow it down to one app.
    Just a thought...

    Re. recording using 32 bit float. Don't forget that the audio stream you are recording is only 12kb/S at 16 bits.
    If I remember correctly, the Pulse audio mixer resamples everything to 44.1k so it can mix different sources together so it maybe worth limiting Audacity to this to see if it helps.

    Frank
     

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