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Author Topic: Wireless Mic making noise  (Read 3881 times)

Ivan Beaver

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Re: Wireless Mic making noise
« Reply #10 on: August 17, 2016, 05:04:13 pm »

How do you have your antennas positioned?

MANY people get it wrong.

They should be at 90* to each other.  So either one pointing up and the other to the side.

Or each one at a 45 OPPOSITE angle.

I know it looks weird, but you will get the most benefit from the diversity that way.

It could be that the particular spot he is standing in is causing a reflection issue and loss of signal.  Moving the antennas (like you already tried-I assume the antennas were moved along with the receiver?) is a good first step
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Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Ivan Beaver

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Re: Wireless Mic making noise
« Reply #11 on: August 17, 2016, 05:05:46 pm »

Being digital does not imply anything about what frequencies it uses. Some of the digital units do use the 2.4gHz band but most pro units do not. I avoid the 2.4 gHz band for anything if I can. It is overloaded.



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Plus the wavelengths are so short that it does not take much to interfere with them.

Just like the high freq in audio, little things make a big difference.  Lower freq just kinda go everywhere.
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Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Jonathan Johnson

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Re: Wireless Mic making noise
« Reply #12 on: August 17, 2016, 05:39:49 pm »

How do you have your antennas positioned?

MANY people get it wrong.

They should be at 90* to each other.  So either one pointing up and the other to the side.

Or each one at a 45 OPPOSITE angle.

I know it looks weird, but you will get the most benefit from the diversity that way.


^^^ This.

If I had a nickel for every diversity RF kit I've seen with the antennas pointing the same direction, I'd probably have a dollar. Or two. If I had a dollar for every time I fixed the same kit over and over again....

Think of a TV with a single "rabbit ear." Or an FM radio with the telescoping antenna. You move it around to different angles to find the optimum reception.

With a "diversity" microphone receiver (whether VHF or UHF), there are actually two radio receivers, and the system automatically switches to whichever one has the strongest RF signal. There's one antenna for each radio. So think about it: if both antennas are at the same angle (parallel to each other), both radios are going to get approximately the same signal strength. So when one loses signal, the other does too. You start to hear interference as the RF signal-to-noise ratio falls because the receiver's automatic gain control increases the RF gain, lifting the desired signal to maintain a steady output but also lifting the noise to an audible level.

So by putting the antennas at different angles, you increase the chances that as one receiver's signal drops out, the other receiver's signal will be stronger, so you have less chance for the signal-to-noise ratio to fall to levels where the noise becomes audible, and less chance of losing the signal altogether.

This works because the transmitter's antenna is not omnidirectional (it's more like a doughnut), and the receiver's antenna is also not omnidirectional in sensitivity. As you move the transmitter around, its "cloud" of signal strength moves around too, so by having your receiver antennas splayed one or the other will always be more optimally positioned.

That's a gross oversimplification, and there may be many technical errors, but the basic concept still applies.

* * * *

If the receiver can be moved closer to the stage, that can also improve the RF signal-to-noise ratio and reduce fading and dropouts. Human bodies are very effective RF shields.

If you're not getting interference (just dropping signal-to-noise ratio), and changing the antenna position and/or receiver placement fixes the issue, and you don't lose signal, there probably is no real good reason to replace your existing wireless microphone kit.
« Last Edit: August 17, 2016, 05:44:41 pm by Jonathan Johnson »
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Isaac South

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Re: Wireless Mic making noise
« Reply #13 on: August 23, 2016, 09:38:55 am »

How do you have your antennas positioned?

MANY people get it wrong.

They should be at 90* to each other.  So either one pointing up and the other to the side.

Or each one at a 45 OPPOSITE angle.

I know it looks weird, but you will get the most benefit from the diversity that way.

It could be that the particular spot he is standing in is causing a reflection issue and loss of signal.  Moving the antennas (like you already tried-I assume the antennas were moved along with the receiver?) is a good first step

Thank you, Ivan.  Moving the receiver has really helped a lot.  In fact, this weekend at church I only heard that noise one time (when the preacher walked about 50 feet away from the receiver).

I will change the antennas to 90 degrees.  I didn't realize that. 
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Isaac South

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Re: Wireless Mic making noise
« Reply #14 on: August 23, 2016, 09:40:28 am »

Jonathan, thank you for explaining that in more detail.  That really makes sense.
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Isaac South

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Re: Wireless Mic making noise
« Reply #15 on: September 06, 2016, 09:11:43 am »

Sorry...one more question.  Could a low battery cause it to make that noise as well?  It's been doing really good until last night.  It started making that noise a few times.  We are really unsure when to change the battery.  I guess we should change it every weekend, but I don't want to waste batteries if it's not necessary.
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Keith Broughton

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Re: Wireless Mic making noise
« Reply #16 on: September 06, 2016, 09:45:31 am »

Sorry...one more question.  Could a low battery cause it to make that noise as well?  It's been doing really good until last night.  It started making that noise a few times.  We are really unsure when to change the battery.  I guess we should change it every weekend, but I don't want to waste batteries if it's not necessary.
A low battery might contribute to the problem this so when it happens, change to a new battery and see if that clears up the noise.
I take it the system has no battery indicator so get yourself a battery tester.
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Jonathan Johnson

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Re: Wireless Mic making noise
« Reply #17 on: September 06, 2016, 12:12:34 pm »

A low battery might contribute to the problem this so when it happens, change to a new battery and see if that clears up the noise.
I take it the system has no battery indicator so get yourself a battery tester.

Looking at the manual for the T2 system, it looks like the mic has a low battery indicator (just below the power indicator). When it is lit, the battery should be replaced.
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ProSoundWeb Community

Re: Wireless Mic making noise
« Reply #17 on: September 06, 2016, 12:12:34 pm »


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