Background "humm" on my Feed

Hello,

I am the Broadcaster for the feed
Smyrna Police and Fire

I was wondering if someone could load the above link and listen for a few minutes. There has always been an annoying "humm" in the background ever since I set up the feed. Looking for any suggestions to resolve this issue. Thanks in advance for your assistance!

John Carmichael

high pitch

could it be fan noise ? are all the inputs set right like mics are off?

Google 'ground loop'.

a ground loop is an unwanted current in a conductor connecting two points that are supposed to
be at the same potential, often ground, but are actually at different potentials. Ground loops are a
major cause of noise, hum, and interference in audio, video, and computer systems.

maybe this link will help you too:
http://siber-sonic.com/electronics/GLoopwhatis.html

Good luck.

Have you tried adjusting the sound level, both the radio volume setting as well as in your streaming program?

Whelen said:

Hello,

I am the Broadcaster for the feed
Smyrna Police and Fire

I was wondering if someone could load the above link and listen for a few minutes. There has always been an annoying "humm" in the background ever since I set up the feed. Looking for any suggestions to resolve this issue. Thanks in advance for your assistance!

John Carmichael

Click to expand...

The hum sounds higher frequency then 60 cycle so don't think it's a ground loop issue. If you are using RadioFeed, The Spectrum Analyzer can determine the frequency and it can be notched out to eliminate the hum.

Try using a different power outlet, sounds like it is hooked to a noisy lamp maybe a touch lamp or a florescent.

Try transformer coupling out of the receiver. Use a 1:1 audio isolation transformer, and don't let the ground side of the output cable connect directly to the chassis of the receiver.

Are you by chance using a RS/GRE/WS scanner? I found the later RS USB programming cables to be incredibly noisy, so much I have ditched using my RS scanners for feeds. If you have one plugged in, try removing it.

The hum sounds higher frequency then 60 cycle so don't think it's a ground loop issue.

Click to expand...

I agree.

Here's a sample of taken from the silent interval. Harmonics begin about 208 Hz extending up to 5388 Hz in 215.5 Hz intervals.

One other thing I noticed is that during a transmission the audio is being clipped. This usually means the audio is too 'hot' for the sound card.

If possible, use the LINE-IN connector instead of the MIC connector on the sound card. Keep gain settings on the mixer set as low as possible for the input you are using, and keep the other inputs muted.
If using the MIC connector is the only option, check the mixer setting again for some kind of boost setting and be sure it is NOT checked.

It sounds to me like there is just some normal low level noise that is being magnified through use of the MIC jack and/or it's mixer settings.

Thanks for all of the suggestions. I am actually using a Motorola Spectra for the feed. I will go check the software settings and follow up.

Ok Folks, the "Mic Boost" was enabled, so I disabled it. It appears to have eliminated most of the buzz. Take a listen and give me your thoughts, Smyrna Police and Fire

quite quiet

much better thanks.

Be carefully with a radio. They have an amp in the speaker output and can easily damage the sound card.