optimizing audio quality of my feed

[gargamello]

Hi,

If this post is not appropriate in this forum section, feel free to move or delete.

I just yesterday got my first feed up and running. I'm using DarkIce on a Raspi with a conventional analog scanner (BCT8) with an audio cable into a USB sound card. Listening to the scanner audio directly, when there's no over air audio, (I've adjusted squelch) it's perfectly silent.

However over my feed I hear a faint, but steady popping or beating noise. I've messed with alsa input levels but that doesn't seem to matter.

Is this a noise issue between my scanner and USB soundcard, a software issue or something else?

Here's the feed in question.
https://www.broadcastify.com/listen/feed/27342

Thanks

 

[Chronic]

I have a sound on a feed and the popping sound is almost perfectly timed to the blinking light on the wifi / or network link light .

 

[gargamello]

I'm using an external USB sound card with blinking LED. Maybe I should introduce a USB extension cable with ferrite beads. I found this helpful when I was playing with SDR dongles. Getting the receiver further from the laptop...

 

[ChrisABQ]

I ordered this noise eliminator and it has virtually eliminated any background noise on my feed. https://www.amazon.com/gp/product/B019393MV2/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

 

[flythunderbird]

I had one of those $5 USB adapters from Amazon to use on my feed and while it did work, it put a lot of noise in the audio. I tried this and it fixed all of my noise problems:

https://www.amazon.com/Behringer-UCA202-BEHRINGER-U-CONTROL/dp/B000KW2YEI

I run it on a Windows-based thin client, but people have been using it with Linux for years.

 

[K9DAK]

Not sure if the Pi will run this... but I've used the Orban Loudness Meter for years with great results: https://www.orban.com/free-orban-loudness-meter/

Set the output level of your scanner maybe 20% below the point where it overdrives the sound card input, and lower the input level so the signal goes no higher than -3 dbFS on the PPM scale (read the Readme on the Orban website). That should give you the best S/N ratio.

Then, after a period of activity on your feed, download an archive mp3 file and look at it with Audiacity... you should see the waveform peaking at about 90% full scale.

This has worked great for my feed: Quad 3 and Lake Zurich Fire

Hope that helps...

I've messed with alsa input levels but that doesn't seem to matter.