[Discuss] Antenna Signal Issues

[matt at mattshields.org (Matt Shields)]

I'm also an Audio Engineer and Guitar/Bass player, just out of the
engineering "mix" for a few years and I haven't kept up with wireless audio
tech.

We've already tried putting transmitters(IEM) and receivers(mics) on a 6'
tall projector stand so it raises them above the audiences heads.  As
mentioned, already eliminated WIFI signals.  And we've used the built in
spectrum analyzer to figure out which frequencies have issues and made sure
we stay away from those channels.  We're pretty sure it's signal dropout
due to distance.

Unfortunately for the IEM's we have 8 musicians and we all want our own
mix.  The great news is we purchased all brand new equipment including a
Behringer X32 digital mixing board, the downside is now everyone (including
me too) wants to take advantage of being able to have their own mixes in
their ears.  Who wouldn't want to be able to use your Android or IOS device
to be able to control your own mix live.

One other solution we're considering is to move all the wireless equipment
onto the stage, but there are logistical issues with this, which we're
willing to accept.  One being the audio engineer doesn't have immediate
access to the transmitter/receiver if necessary.  Second being that's
channel on our digital snake that are consumed by wireless devices.  So the
ideal solution would be to come up with some type of better antenna array
at the FOH board.



Matt


On Wed, Jun 4, 2014 at 3:46 PM, Stuart Conner <genuineaudio at gmail.com>
wrote:

> I'm a sound guy with experience in wireless.
> I don't know from your post if you're having dropouts on the mic side or
> the monitor side of the equation.
>
> First off forget about combining antennas for mics and monitors.
> Nevermind the different manufacturers, the 566MHz and 2.4GHz are different
> areas of radio spectrum, so an antenna built to be efficient in one range
> won't be for the other.
> With only 4 wireless mics, I don't think an active antenna distro would
> make sense.
> They're pricey and add bulk to the equipment rack.
>
> Modern wireless systems usually have a frequency scanning feature, learn
> how to take advantage of this automatic channel finding feature. Start with
> all transmitters off, do a channel scan on the first receiver, sync the
> first mic to it and leave it on. Now scan with the second receiver, sync
> that mic and so on.
> I remember the old days we had to research ahead of time to know what radio
> and tv stations were in the area and what band our mics used and then
> determine how few channels were left available to use wireless.
>
> Do your best to have the receiving antennas above the heads of the crowd,
> open the rack's back lid and use fresh batteries in the transmitters.
> Bodies block and absorb RF signals, make sure the belt pack antennas are
> free and not hidden under arms or tucked in next to the skin. On hand-held
> mics make sure to know where the antenna is on the unit (usually the bottom
> tip area) and have the performer avoid holding the mic there.
>
> On to the in-ears:
>
> Eight transmitters close together may cause inter-modulation.
> If they're all in one rack, you might want to separate some.
> Perhaps 4 and 4, then put the second rack in another location on stage near
> the performers using them, then use cables or a sub-snake to get the mixed
> signals to them.
> Another solution may be to use an antenna combiner like this:
> http://en-us.sennheiser.com/ac-3 IF that is in fact the problem. It look
> like you would need two of those for your rig if you go this route.
>
> Ask yourself: Are any two or more units transmitting a nearly identical
> monitor mix?
> If so, you may want to just have more than one performer tune their belt
> pack receiver to the same transmitter frequency. It's similar to having
> many people listening to the same radio station. The trade-off is that the
> people sharing the mix won't be able to ask for "more me" in the mix
> without conflict. Remember, this trick doesn't work for microphones, each
> transmitter needs it's own frequency but many receivers can tune in.
>
> Same rules apply for the antennas as with the mics.
> Get them high and open to the air. Make sure each performer has a clear
> line of sight to the transmitter antennas and wears their belt pack on the
> side facing the antennas.
> use the frequency finding feature of the system to find clean channels one
> at a time with the previous transmitter still on.
>
> I always try the easiest, cheapest solutions first. Simpler is better.
>
> Stu
>
>
> On Wed, Jun 4, 2014 at 12:00 PM, <discuss-request at blu.org> wrote:
>
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> > Today's Topics:
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> >    1. Antenna Signal Issues (Matt Shields)
> >    2. Re: Antenna Signal Issues (Bill Horne)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Wed, 4 Jun 2014 09:25:05 -0400
> > From: Matt Shields <matt at mattshields.org>
> > To: discuss at blu.org
> > Subject: [Discuss] Antenna Signal Issues
> > Message-ID:
> >         <
> > CAOTD2YRqNRmFOxYEBOoXwEAWKCo1K1WqS3YwP87UiRk1v_iihA at mail.gmail.com>
> > Content-Type: text/plain; charset=UTF-8
> >
> > This is not computer or linux related but I'm hoping that someone on the
> > list might have some technical experience in radio signals or wireless
> > systems for audio engineering.
> >
> > I have the following wireless equipment.  2 wireless handheld mics, 2
> > wireless headset mics and 8 in ear wireless monitor systems(IEM).  We're
> > having issues with signal dropout probably due to antenna issues, those
> > cheap plastic ones that come with the units.  Both the handheld and
> headset
> > mics run on the 2.4Ghz spectrum and the IEM's run on 566-608Mhz.  We have
> > already figured out which frequencies work best for the environment, so
> > that's not an issue and we don't have any conflicts with WIFI.
> >
> > So the issue we think we have is range issue.  Can I buy a high gain
> > directional antenna and a splitter and run cables to each of the
> > devices(single antenna array)?  Or do I need to have the mic's and IEM's
> > use 2 separate antenna's since one is send and one is receive?  Or do I
> > need to have every system use a separate antenna?
> >
> > A few years back I did something similar with my WIFI router, bought a
> > larger +12dbi gain omnidirectional antenna and my range almost doubled.
> >  The idea is that if I get a more directional antenna I should get a
> decent
> > amount of gain.
> >
> > Here's the equipment I'm using:
> > 2x Line 6 XD-V75 - handheld wireless mics
> > 2x Line 6 XD-V55HS - headset wireless mics
> > 8x Sennheiser EW300IEMG3-G - In Ear Wireless Monitor
> >
> > Matt
> >
> >
> > ------------------------------
> >
> > Message: 2
> > Date: Wed, 04 Jun 2014 11:37:31 -0400
> > From: Bill Horne <bill at horne.net>
> > To: BLU Discussion List <discuss at blu.org>
> > Subject: Re: [Discuss] Antenna Signal Issues
> > Message-ID: <538F3D3B.5060102 at horne.net>
> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >
> > On 6/4/2014 9:25 AM, Matt Shields wrote:
> > > This is not computer or linux related but I'm hoping that someone on
> the
> > > list might have some technical experience in radio signals or wireless
> > > systems for audio engineering.
> >
> > Wouldn't you rather talk about DMARC? ;-)
> >
> > > I have the following wireless equipment.  ...
> > >
> > > So the issue we think we have is range issue.  Can I buy a high gain
> > > directional antenna and a splitter and run cables to each of the
> > > devices(single antenna array)?  Or do I need to have the mic's and
> IEM's
> > > use 2 separate antenna's since one is send and one is receive?  Or do I
> > > need to have every system use a separate antenna?
> >
> > Splitters cost power; as much as 1/2 of your power can be lost when
> > using them.
> >
> > Directional antennas are a double-edged sword: you get /some/added gain
> > in /some/ direction, but they are never perfect, and will tend to leave
> > dead spots in odd places.
> >
> > I suggest you start simply: elevate the transmitters and receivers above
> > the floor as much as you can, for example, by placing them on top of
> > emergency lights. Try to get wireless mic receivers out in the middle of
> > the crowd instead of on the stage: they work better when tied to
> > ceiling-mounted video projectors in the middle of the room.
> >
> > Let us know how well that works. Simplest is always better.
> >
> > Bill
> >
> > --
> > Bill Horne
> > William Warren Consulting
> > 339-364-8487
> >
> >
> >
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> >
> > End of Discuss Digest, Vol 37, Issue 2
> > **************************************
> >
>
>
>
> --
> Thanks,
> Stu
>
> 617-462-0552
> genuineaudio at gmail.com
> blue23 at netzero.net
> stuart.conner at state.ma.us
>
> Stuart Conner
> 62 Rhodes Cir
> Hingham, MA 02043
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