Sennheiser lavaliere interruption
 

Hi!

We have 2 sets of Sennheiser ew100 G2 wireless lavaliere mics.
When we are filming somewhere outdoors (nature, city etc..) we have constant problems with interruptions.
We cannot film even 30 seconds of talk that sound doesn`t get interrupted one or two times. It is like frequency problem, but we have tried to change frequencies many times and it is always the same problem.

Does anyone else have similar problems? How do you solve that? Are there any other better lavaliers that doesn`t have that problems?

Thanks for help

Re: Sennheiser lavaliere interruption
 

Assuming the signal is intermittently dropping out, going silent, it might be that you are experiencing a phenomenon known as "reflectance." That is typically caused by the radio signals bouncing off metal objects (reflecting off) in the immediate area where you are shooting. One way to at least partially solve the problem is to use a "true diversity antenna." You can do a search on this forum. Seems I remember a couple of threads. Also can do a general online search using those terms to learn about the phenomenon. I experienced it while on a shoot at a power plant. Then I bought a receiver with a true diversity antenna. Haven't had the problem again, yet.

Another problem is having the signal blocked by an object.

Another possibility is a bad cable somewhere and you lose the signal when the cable is jiggled.

Drop outs with some "static" are often due to interference from other wireless devices, cell phones, blackberries, tablets, walkie-talkies (Nextel, Radio Dispatched Trucks, Hotel or other venue communication systems).

Sometimes, I have to use cabled microphones, with long xlr cables. There's a saying "when you're able, use a cable..."

Re: Sennheiser lavaliere interruption
 

Can you post a short clip so we can possibly ID whether it is an RF or cable/connection/acoustical issue? What kind of distances are you expecting?
Have you tried the receiver's scan feature and /or Sennheiser's on-line 'frequency finder' utility to find 'unused' frequency channels.. (though I don't know it's availability for your area)
Other than that, keep the transmitter and receiver in 'line-of-sight' and do not let the system's antennas touch skin or be in close proximity to devices that spew RF like cell phones and other wireless equipment... in fact, it's recommended to have these devices turned off.
Are there any other better lavaliers that doesn`t have that problems?
- All wireless systems experience problems.. There are 'better' more expensive systems, but without proper due diligence in set-up, improved reliability would be minimal at best.

Re: Sennheiser lavaliere interruption
 

Some people say it's important to have the transmitter and receiver antennas pointing in the same direction (vertical or horizontal). That worked for me a couple of times when I had breakup like you describe.

Re: Sennheiser lavaliere interruption
 

There are many different things that could cause "interruptions". As Mr. Reineke suggested, posting an example would help us identify what kind of "interruption" you are hearing.

It is necessary to identify exactly what kind of problem you have before we can offer any suggestions. Else we could offer you 50 different things to try, and only 5 might be relevant to your problem.

it would also be useful to give more complete explanation of how/where you are using your equipment. How far apart are the transmitter and receiver? Do you try to make this distance as short as possible? Are you careful to fully extend both transmit and receive antennas? Do you have this problem only when in a city, or out in the countryside also? Are you setting the frequencies of your two systems to compatible frequency channels so they don't interfere with each other?

it sounds like you think it is an RF (interference, or propagation) problem. But are you sure it isn't an intermittent break in the microphone cable, etc?

Re: Sennheiser lavaliere interruption
 

Another possibility is a broken mic. cable.

I have often seen people just wind the mic. cable round the transmitter after use - if you don't leave a loose loop at the start you strain the cable as it comes out of the plug and can cause a break in the cable.

This can cause intermittent operation.

Re: Sennheiser lavaliere interruption
 

I have had a similar problem using my Zoom H2 when it's on the wedding guests dinner table and the symptoms sound a bit like morse code here and there. I'm wondering if it could be down to cell phone interference.

Re: Sennheiser lavaliere interruption
 

Without a listen, we're guessing. Can we hear the problem?

Re: Sennheiser lavaliere interruption
 

Thanks for a lot of replies. Here I have cut some examples where you can hear what am I talking about:
https://www.dropbox.com/s/g4u6ioj225...terruption.wav

@Les Wilson, we will try that, normally the lavaliere on speaker is put verticaly and the one on camera is horizontally. Never thought that can be the problem.

@Richard Crowley, mostly we have interruptions outdoors (especially in cities - we didn`t record too much in nature areas so I can`t say much about that). When we shoot in studio we have that problem very rare. Last shooting that we had was stedicam shot with speaker walking 3-6 meters in front of camera. Transmitter is fixed at the back of speaker on the belt (vertically) and receiver is on the camera (horizontally). The antennas on Sennheiser ew100 G2 are fixed and cannot be extended. Regarding frequency channels as I remember there are 8 of them and we always put the transmitter and receiver on the same channel.

The problem is not with the cable because we tested it and tried 3 different new cables.

Currently I don`t have lavaliers with me but next week I will try some of your suggestions.

Appreciate your help

Re: Sennheiser lavaliere interruption
 

Classic RF dropout. Not a cable fault. My guess is simply the path. There are a few best practice things to do first. Aerials - vertical on both is best, because they should radiate omnidirectionally. One horizontal and the other vertical is the worst setup. On top of this, a horizontal aerial will have it's nulls left and right, so as the unit is turned the received signal can drop down even further.

All that is happening is that the receiver is working on the edge - at one moment there is just enough signal, then a small body reposition, or camera movement, and it drops below the threshold, the squelch shuts and you get the 'phuttt' noise. If the person wearing the transmitter has it under something, so the aerial is up against their body - then the body absorbs a great deal of the output, especially if they are sweaty. At the other end, the receiver can be blocked by anything in the way too - even the metal of the camera.

I'd put the camera receiver vertical, and repostion the transmitter to be clear of the body (if it isn't).

If you separate your receiver and transmitter by around 10 metres, and then wave the receiver around, listening on headphones, you can usually replicate the dropout. horizontal aerial on one pointing towards the other is usually the worst.

Re: Sennheiser lavaliere interruption
 

I concur with Paul.
Furthermore, if the transmitter's antenna is in contact with the wearer's skin, you will loss about 80% of RF gain.
Also keep the squelch set to the default 'Low' setting. The transmitters audio gain (sensitivity) should also be set optimally.
Heed my previously stated recommendations.

Re: Sennheiser lavaliere interruption
 

I completely agree with Mr. Johnson.

Radio signals are polarized, just like polarized light. Both antennas must be in the same plane for maximum transfer of energy. When they are cross-polarized (as you have been doing) you can expect a reduction in RF level of up to -20dB. Mind you, that won't reduce the audio level, but it will greatly reduce the working distance before you have dropouts.

Imagine that an antenna's coverage pattern is like a donut, with the antenna wire running through the center of the hole.

If the antenna wires are horizontal, half of the coverage area will be toward earth, which is of no use whatsoever, and there will be dead spots pointed along the axis of the wire, so when the transmit antenna (or the receive antenna) rotates horizontally, you might encounter a big drop in signal.

If the antenna wires are vertical, the coverage "donuts" will be horizontal, which is ideal: either the talent (transmit antenna) or camera (receive antenna) can rotate 360º in a horizontal plane, and there will be no significant change in the coverage area or range.

Always keep both antennas vertical!

Re: Sennheiser lavaliere interruption
 

.............................. Always keep both antennas vertical

Does anyone know whether this also applies in real world use of the G3 (I note the OP is using the G2).

The G3 receiver brochure states "this diversity receiver uses the ground connection of the line cable as its second antenna to provide improved reception"

and as long ago as April 2009 John Willett posted on this forum in response to "what is adaptive diversity":

It's another name for "antenna diversity".

The camera-mount receiver is too small to be "true" diversity as that needs a second receiver inside (true diversity is two complete receivers feeding a single output stage).

The G3 camera-mount receiver is the same size as the G2 - the second antenna is the output cable. It has a single RF section and a special circuit that monitors the two antennas and uses the one with the strongest signal.

So it's a diversity receiver, but with the two antennas being switched between a single RF stage, rather than two antennas and two RF stages being switched at the output of the RF stage.

It was deemed to be better this way for on-camera use, as it keeps the size of the receiver down.

My thinking is that although normally its pretty easy to ensure that the antenna on the talent is vertical but rather hard to keep it horizontal, the receiver when mounted on cam is going to be horizontal if placed direct in the cold shoe.

Would you recommend using a small ball and socket head to mount the receiver vertically on the cam or is that largely irrelevant when using the adaptive diversity G3? Maybe that would be a good reason for the OP to bite the bullet and upgrade to the newer G3 thereby also sidestepping other potential conflicts due to available frequency changes.

Pete

Re: Sennheiser lavaliere interruption
 

The diversity feature is a neat idea, but using the output cable as an aerial is a bit of a compromise - however - in diversity systems, with two close spaced aerials, the real problem is that if both aerials are close together, and in the same plane, as most are. If the transmitter or receiver is in a null, and thus low or zero signal, the other receive aerial will probably be exactly the same. it's standard practice in mains powered radio receiver racks to have the aerials in different locations, on the premise that if one path is down or poor, the other to the second aerial may well be in the clear. People also develop little tricks with polarisation. If one aerial is vertical, then some people will have the second receive aerial at an angle. The theory is that if for some reason the polarisation of the signal is not vertical, then as the signal strength drops, an aerial with an alternative polarisation should go up! The G3 system with one aerial up, and the other (the cable) diagonal to the XLR socket should cover that one.

I'm not sure that Sennheiser's system could really be described as "better" - as it shares one RF section, but it's clearly better than a non-switching system. I have a transmitter for a guitar that uses the cable as the aerial, and it's not really that efficient, as the aerial isn't resonant, and has to be tuned electronically - which means the aerial just isn't so good at capturing RF energy. Still better than one aerial though!

I always mount mine on the rear, vertically. There are a few pictures of cameras with receivers mounted on the top with the aerial pointing towards the front. This is the absolute worst position. The deepest null is an extension along the aerial's direction.

Re: Sennheiser lavaliere interruption
 

A common practice when one has a pair of close~spaced "whip antennas" is to put them into a "V" formation, rather like the old VHF TV "rabbit ears" from the 1950s. The theory being that having two antennas 90 degrees apart in alignment gives the best possible (in such a limited constraint) coverage of radio waves coming in direct or reflected. It sounds goofy and is counter-intuitive when the transmitting antenna is most likely vertical. But the alignment of a monopole transmitting antenna doesn't really affect the "plane" of the transmitted radio waves.

Re: Sennheiser lavaliere interruption
 

I'd like to see a reference for that statement, as that's quite different from what I consider to be true.

Everything I've learned about antennas -- going back over 40 years as an FCC-licensed broadcast engineer, and over 35 years as a licensed radio amateur -- tells me that if the antenna is anywhere near being a tuned monopole (or dipole, for that matter) then the polarization of the radiated field corresponds to the physical orientation of the antenna wire.

(The only time the transmitted wave has no polarization is when the antenna length is very much shorter than 1/4 wavelength at the frequency under consideration -- essentially a "point source" antenna. In that case, there is no polarization and the radiation pattern is a sphere. But wireless antennas are not nearly small enough to be a "point source" and in fact they're pretty well tuned to the transmit frequency, to achieve reasonably good coupling efficiency with the transmitter electronics.)

The waves from a vertical antenna aren't radiated in a plane. (Or perhaps when you said "plane" you meant "polarization.") As the antenna length increases from the theoretical point source to a vertical wire of tuned length, two things happen: (1.) the signal polarization becomes more and more strongly vertical, and (2.) the radiation pattern becomes more and more flattened or "pushed in" at the top and bottom, changing from a sphere to a torus (roughly a donut shape).

So if the antenna is vertical, the polarization will be vertical, and the torus (showing the signal strength) will be horizontal (in other words, as if the "donut" is laying flat on a table). If you walk around 360º in a horizontal circle, staying an equal distance from the antenna (which is located in the "donut hole"), the signal strength should be equal at all points. OTOH, if you move in a vertical circle, the signal strength will drop as you get away from the plane of the torus, and will theoretically drop to zero when you are located along the axis of the antenna.

Now, indeed, polarization is "mirrored" if the signal bounces off a good conductor (e.g. a large metal structure, etc.). That is important when circular polarization is used: right-hand circular will reflect as left-hand circular, and vice versa. But a resonant vertical transmit antenna will produce a vertically polarized signal at short range, and that will be reflected as a vertically polarized signal as well.

Re: Sennheiser lavaliere interruption
 

What can I say Greg? 100% agree. It's a very curious statement, and seems to go against everything I was also taught.

Re: Sennheiser lavaliere interruption
 

Agreed - Audio Limited do (used to do) a rt.angled antenna so that one was vertical and the other horizontal.

On a mains receiver, having the two antennas as a "V" has the same effect.

Re: Sennheiser lavaliere interruption
 

Wish this thread had a "Like" button..... anyway, how does all this work with plugon transmitters? I use one from my sound guy's mixer to my camera. Is there a preferred orientation for the antenna on my receiver for a plugon?

Re: Sennheiser lavaliere interruption
 

Vertical still works best because the aerial pattern (like a donut, explained above - see torus) has width, but not much up or down, so makes a better match with people moving in front of the camera. The plug in transmitters, or handhelds are always up in the clear, not hidden behind, or in pockets - so the path loss is much better - and dropouts fewer.

Re: Sennheiser lavaliere interruption
 

Unless you have a rigid antenna fastened to some radio-transparent spacer which is attached to the body of the person who remains upright at all times, you don't really have anything near the equivalent of traditional propagation factors of broadcast antennas. More likely, you have a piece of flexible wire hanging at some random angle (or stuffed into a pocket,etc.) and in close proximity to a large RF-absorbing body. And more often than not, that RF-absorbing body is BETWEEN the transmitting antenna and the receiver.

Re: Sennheiser lavaliere interruption
 

Nice bit of fudging - but that's not really been the case since we were working VHF with a screwed up piece of wire dangling down - most UHF aerials are now quite stiff. Whichever way you think about it, a horizontal aerial placement will also have rotational effects, which a vertical doesn't have. Sure - body effect has an impact, but body effect with a potential end on aerial path top the receiver IS worse.

I commercial comms systems, vertical polarisation is the standard for all things mobile. Why? Because it is the most efficient. Horizontal aerials offer directivity.Obstacles can be in the way in any polarisation. Typical video use has movement mainly in the horizontal plane, which makes vertical polarisation the most effective. Just how it is.

Re: Sennheiser lavaliere interruption
 

Perhaps we're picking nits here.

If the wireless mic is used optimally, the antenna wire should end up being much closer to vertical than to horizontal. And therefore the original transmitted signal should be pretty much vertically polarized.

But yes, absorption and reflection can change the polarization from vertical (as it was transmitted) to something else that is not predictable. This problem will be worst when shooting indoors, where there are lots of metal conductors of various dimensions and various proximity to the transmit antenna. If a true vertical signal is reflected by a vertical conductor, the polarization should be unchanged. But if a vertical signal is reflected by an oblique conductor (e.g. the arm of a metal chair) then there may be a change in polarization.

From my past experience, watching the signal indicator lights on diversity receivers, I got the impression that a horizontal antenna got a lot less useful signal than a vertical antenna. (This was with a "mostly vertical" dangling transmit antenna.) But yes, using a bit of a "V" pattern, when one antenna tilts perhaps 15º to the right, and the other perhaps 15º to the left, seemed to work quite well. I've seen this used extensively. The polarization undoubtedly does not stay precisely vertical.

Still, as Mr. Johnson points out, vertical is certainly preferable because of the pattern. A horizontal wire antenna will be dead along the axis of the wire. If you seemingly "aim" the wire toward the transmitter (by sighting along the wire as if it were a pointer) you will be aiming the antenna in the worst possible direction. The horizontal torus pattern of a vertical (or nearly vertical) antenna will obtain the best coverage around the room. And since the receive antenna(s) is(are) (nearly) vertical, you should try to keep the transmit antenna as close to vertical as possible.

Re: Sennheiser lavaliere interruption
 

Here's a summation from my point of view.

Engineers and experienced pros will argue this stuff forever, which is all well and good.

For the practical shooter in the field just trying to record good audio here's the drill.

Wireless is always prone to more potential sound affecting audio issues than wired mics. If you truly need a wireless rig, it's important to make sure ALL the components are in proper operating order. This includes the antenna systems AND a dependable source of power.

In order to get quality results from any wireless system you need one thing WITHOUT FAIL. And that's a monitoring system that lets you hear your audio AT THE LAST STAGE OF THE CHAIN in real time.

That means dependable headphones and a place to plug them in that's not too far down the audio chain to hear problems in later stages.

With such a system in place, if you do experience signal issues - it's pretty easy to test to see where they are coming from. In the case of wireless units, for example, you can simply remove the transmittter from wherever it isn't working and put the transmitter and receiver in closer line of sight proximity. If the problem persists, it's NOT distance or antenna masking. Similarly if you re-orient either the receiving or transmitting antenna and the problem significantly changes, then and ONLY then is it reasonable to assume that the problem is an antenna problem.

Theory is wonderful. Nothing would ever get created without it. But in the field with people waiting for you to deliver results theory is at best, instructive, and at worst, misleading.

I've had to do stuff that people who know the theory behind radio mics would say were butt head dumb (like gaffer taping a body pack transmitter to a handheld transmitter when I needed two signals and the performer costume made it totally impossible to hang a body pack on that person ANYWHERE! ) but at the time it was the ONLY way to solve my problems and the gods smiled and it worked great. Would I recommend it? Hell no. But my job isn't to get the theory right, it's to get the performance capture right. Period.

For my money, the real thing that matters in this thread is the practical figuring out where the problem is coming from in real time - and fixing it RIGHT THEN. It sounds like on your set someone let the problem get baked into your signal out in the field rather than stopping to fix it at the time.

That's the big lesson. And the most valuable one you can get here. Much more valuable than all the antenna theory in the world.

My 2 cents, anyway.

Re: Sennheiser lavaliere interruption
 

Mr. Davis:

I agree that, in the field, a quick solution, and sometimes trial-and-error, are needed, obviously.

The reason I thought it would be helpful to interject some antenna theory is that the OP stated:
The OP had the problem repeatedly, and did try to solve it in the field (e.g. he tried several different interconnect cables to isolate the problem). But since he did not know antenna orientation was a variable, he never tried that. So, clearly, the OP needs some information.

I suppose one could just say "try moving the antennas" but I don't think that's really enough. For example, he might change from a horizontal antenna perpendicular to the transmitter, to a horizontal antenna pointed toward the transmitter. Neither one would be the ideal solution. IMHO it's better to give a little extra information, and let the OP (or any reader) make an informed decision in any given situation.

That's my 2¢ worth...

P.S.: Don't worry... I've never seen any theory that says gaffer tape is bad. ;-)

Re: Sennheiser lavaliere interruption
 

Man, this is just amazing information!!!!! Some of it I'm actually able to follow;-)

You guys are the best.

Jonathan

Re: Sennheiser lavaliere interruption
 

I was looking for a smaller wireless system as currently I use a older azden 500 udr (http://www.azdencorp.com/pdf/TV_Tech...UDR_review.pdf) which I got second hand a few years back but in combination with my smaller camera's it's too bulky. Thing is I heard from colleagues that work with smaller systems, similar to the sennheiser to which is refered to by the op, that they do experience occasional dropouts in sound. This is something I never have encountered with my azden and it is essential to me that this doesn't happen during a live shoot. Beside the direction of the antennas, is there something a wireless receiver must have to perform with a much higher reliability of not loosing the signal? Was I just lucky with my Azden's to never have experienced any issues?
Btw, great info in this thread, only most of the stuff is way over my head :)

Re: Sennheiser lavaliere interruption
 

All joking aside, the most useful thing to remember is that the most expensive radio system is nearly as good as a $10 cable! In theatre we spend an awful lot of our time listening to the radio channels, attempting to predict which channel is going to be a problem, praying that the talent doesn't take a step rightwards into the RF hole you know is there. When you hear a 'phutt', were you quick enough to spot which channel it was - or not?

You stick the pack onto somebody, with the aerial sticking up, but you can see the bulge that tells you it's gone horizontal when they sat down, and you are using directional paddles, and the 90 degrees is going to give you problems at any moment.

Despite all the theory we've explained, RF is still a black art, and there is always magic involved.

You can do all the planning you like, but unexpected events always mess up. When I do sports, I often stick a shotgun on a short stand, in clear line-of-sight to my camera up in the stadium - works fine, but last time - the nasty phut in the headphones made me cast a glance towards the mic and there was a big fat bloke sitting down right next to the mic, directly in the way - and RF doesn't like it. All the places he could have sat, he picked there. Yet, I've had complaints a handheld mic was coming through somebody else's PA system over 500m away. Quite funny - they had an outside event that had finished, but they had left their PA on, but in a locked up building - and my microphone was relaying everything to people walking past!

Re: Sennheiser lavaliere interruption
 

Noa, I think you are just lucky. I had that same Azden a few years back and had some similar issues. I loved the professional look of that thing though.

I also have 2 sets of the sennys, the older one and the later ones. The older ones never suffer that problem. The newer one occasionally does.

There is another thread on this board that addresses that issue.

Re: Sennheiser lavaliere interruption
 

If you monitor the RF level at the receiver on ANY system, you will see that for the majority of the time, the level is virtually full, but at the point they go 'phutt' the signal strength drops to virtually nothing. With 50mW or so that's not really very much, so finding nulls is very easy. Diversity reception is by far the best solution, but it's still not perfect. Apart from dropouts, we also have co-channel interference, intermodulation interference, and of course receiver desensitisation. I've got many different makes of kit, and all of them, at one time or another have been compromised.

Re: Sennheiser lavaliere interruption
 

The antenna of a plug-on will tend to have slant polarisation and could move from horizontal to vertical.

The best is to put the receiver antennas as a "V" as I suggested above with an angle between them of about 90°.

Re: Sennheiser lavaliere interruption
 

Just a thought - years ago, we used to use aerial combining for point to point links to squeeze an extra 3dB. Using a short matching length of coax in a small housing. Just kept impedance at the correct 50Ohms, yet allowed extra gain.

It occurred to me that John's classic V compromise to allow for polarisation shifts could be paralleled in this way, then another identical one fed from the other aerial socket to a remote position. This would provide better protection from nulls, yet cope better with polarisation shifts. AND - it wouldn't cost very much.

As a quarter wave working without a proper ground plane isn't really a proper 50Ohm match, you'd probably want to use dipoles in an 'X' formation, but I've not heard of anyone trying this. I've never liked paddles very much, as log periodics, especially short ones don't really make much sense unless they're the right distance away as the polar pattern on a smaller stage makes placement critical. You often see them pointed from the wings, straight across the stage, but this wastes the audience side of the pattern, and can offer dead spots upstage.

We started with a 'fault' that could have been all sorts, got it tracked down to RF issues, and are now etting quite deep. Ironically, the G3, with dangly output cable might well offer the best out of the box solution to polarisation issues.

What is certain is that the worse case must be this:
http://www.thecameraclass.com.au/ima.../SonyZ7P13.jpg

Re: Sennheiser lavaliere interruption
 

Hey guys,

I know I am late ot the party, but I would like to get some recommendations for better wireless systems that are less prone to this interference.

I have had a couple Senn. 100 systems which are now illegal and they have always suffered from this Phut, pzzzt behavior. I try to keep the aerials upright but it always seems to happen during live events where you can not stop and go change something.

It does seem like distance plays a part and the distance on these mics seems to be a lot sharter for perfect operation than we typically use them.

So, I was wondering if you could advise from personal experience which system would be an improvement in range and reliability of signal.

Thanks for your input.

Re: Sennheiser lavaliere interruption
 

Your system is likely not set-up properly. Have you checked and avoided TV station frequencies in your area and done a scan prior to shooting.
An occasional RF hit is common to all wireless systems. Lectro, Zaxcom are more bullet-proof but cost 3x that of the G2/3 systems and increased range would not be by much if at all.. if fact, some tests indicate further range than the $3k Lectro systems.
Multi-path dropouts can be reduced by using a diversity system. The G3 is a diversity system, the G2 is not.

Re: Sennheiser lavaliere interruption
 

The problem is not the Sennheiser, it's the frequency you have chosen and how you have set it up.

Try and keep the antenna off the body - if the transmitter antenna touches the body you will attenuate the signal by as much as about 70dB! Even a short distance off the body improves transmission amazingly.

This will be true for all radiomic. transmitters, not just Sennheiser.

Your problem sounds like either what I have described above and/or you have chosen a frequency too close to another/more powerful transmitter which is causing interference.

You should get a good 100m range with evolution systems and maybe mote (depending on the receive antennas used and how you have set them up).

I have had three-quarters of a mile range on a Sennheiser system with good antennas.

Re: Sennheiser lavaliere interruption
 

I knew I had posted before about how far the Sennheisers can reach under ideal conditions, but it took me a while to find it: post #7 in this thread

Re: Sennheiser lavaliere interruption
 

Thanks for your reply. It is tough to get the transmitter away from the body when a person needs to wear it! I try to have folks put it in pockets if possible, but they want to hide it.

The trouble with choosing a frequency is that the interruptions are random in nature. So you can set the thing up, go live then the "stuff" happens. How does one know these things?

Re: Sennheiser lavaliere interruption
 

I found Potential for LTE interference to Wireless Audio Report (OFCOM) interesting reading, but it is obviously targeted at the UK situation with the dreaded 'Digital Switchover' and the introduction of 4G. Pity it doesn't name the brands and models tested, but it does seem to indicate that you get what you pay for to some extent.

Re: Sennheiser lavaliere interruption
 

It's not the transmitter that has to be away from the body, but the antenna.

A good way with the Sennheiser systems is to reverse the belt clip and mount them with the connections pointing down. Clipped to the belt this often holds the antenna off the body.

Also, make sure you put the mic. on properly, hide the cable underneath the clothes, etc., and not just leave it all hanging.

Re: Sennheiser lavaliere interruption
 

On radio systems everything conspires against you. We're talking low power, very inefficient aewrial systems both ends of the chain, and proximity to sponges that soak up RF energy - as in people! In clear space, as John says, distance can be pretty remarkable, but equally I find getting it to cross an 8m stage intact can be quite a challenge. Diversity receivers can help, but in many cases, the benefit of these is only evident when the receiver aerials can be some distance apart. Very rarely is distance the real issue, because a quick look at the signal strength meters shows that they usually sit on either maximum or zero. The two feet of travel that the wearer needs to do can slam it from full strength to zero in one pace, and you only know where the null is when it happens. If you watch the Grand Prix you see people with their radio systems aerials on their headsets, up in the air, clear of obstacles and the improvement is pretty drastic. With packs in a pocket, pressed up against a body, instead of omni directional output, up to 180 degrees has to go through a body. add in more loss from angle mismatches between TX and RX aerial polarisation and it's a wonder we ever get them to work. In my theatre work, where budgets are always tight, we still find the money for somebody to look after radio mics - because they're that much trouble. Batteries, dodgy cables, dodgy mic placement, RF issues, the problems go on and on.