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Wireless antennae: on cart or remote


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I notice that in most cart pix I'm seeing that you guys are mounting your RX antennas to the cart itself.  This is obviously working

for you or you wouldn't do it, but I've found it useful to be able to put the antenna where I want it--usually a lot closer to the action than where my cart can be.  Are you cats always on those cart-mount antennas, or do you sometimes supplement w/extra ones closer?  How high do you run those cart antennas? 

Philip Perkins

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Guest tourtelot

Very rare that I run an antenna away from the cart  Find that I almost never need too.  Lectro Venue with two Lectro GPU antennas as "first up" and then to Sennheiser shark-fins if necessary.

D.

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I notice that in most cart pix I'm seeing that you guys are mounting your RX antennas to the cart itself.  This is obviously working

for you or you wouldn't do it, but I've found it useful to be able to put the antenna where I want it--usually a lot closer to the action than where my cart can be.  Are you cats always on those cart-mount antennas, or do you sometimes supplement w/extra ones closer?

Many days we have to move the cart constantly and quickly.  It becomes a nuisance to have two more things to collect, cable back in, and then set and cable out again once repositioned.  If there are RF issues, sure, we might run the antennas out farther, but if there is no reason to (eg good RF performance from the cart) it becomes more of a pain than a help.  Similarly (as you are no doubt already aware) adding lengths of many types of cable to the antenna can make it more lossy, even if it is physically closer to the action. 

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Many days we have to move the cart constantly and quickly.  It becomes a nuisance to have two more things to collect, cable back in, and then set and cable out again once repositioned.  If there are RF issues, sure, we might run the antennas out farther, but if there is no reason to (eg good RF performance from the cart) it becomes more of a pain than a help.  Similarly (as you are no doubt already aware) adding lengths of many types of cable to the antenna can make it more lossy, even if it is physically closer to the action. 

Us too--moving a lot, hence our use of a single cart (no follow cart).  But often I end up with a wall of metal (grip and electric) between me and the talent, and it seems helpful RF wise to be able to repo the antennae (2 fins on a crossbar, one stand, 30 ft max of cable).  I seem to end up outside of buildings, around corners, behind trucks etc a lot....  But maybe I'm overtraining w/ the ant.s.

Philip Perkins

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Us too--moving a lot, hence our use of a single cart (no follow cart).  But often I end up with a wall of metal (grip and electric) between me and the talent, and it seems helpful RF wise to be able to repo the antennae (2 fins on a crossbar, one stand, 30 ft max of cable).  I seem to end up outside of buildings, around corners, behind trucks etc a lot....  But maybe I'm overtraining w/ the ant.s.

With a 30' piece of cable, considering that 10' of that is going to get chewed up by placing the antennas high on the stand and another 7' or so is going to have to be taped down on the ground so nobody trips, it seems like the difference one could make in terms of subject to antenna distance is pretty negligible.  But yes, I do it also sometimes if it becomes absolutely necessary.  If the situation calls for it I prefer to try and switch antennae (from a dipole or log to a yagi, for example) if I'm having trouble than physically move everything closer as it's easier to do.

As to whether or not you're overdoing it, it really comes down to whether or not you are having problems.  Most wireless mics have some sort of RF meter on them and one can usually get a pretty good idea of performance that way.  Whenever possible we also try and do a walk test before wiring talent or making a boom wireless so we can make an educated decision about which frequencies have the best performance and whether or not we need to move closer.  But if it's working well from the cart position, I usually have enough else to do that fixing unbroken things falls pretty low on the priority list.

Regards,

Noah Timan

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With a 30' piece of cable, considering that 10' of that is going to get chewed up by placing the antennas high on the stand and another 7' or so is going to have to be taped down on the ground so nobody trips, it seems like the difference one could make in terms of subject to antenna distance is pretty negligible.  But yes, I do it also sometimes if it becomes absolutely necessary.  If the situation calls for it I prefer to try and switch antennae (from a dipole or log to a yagi, for example) if I'm having trouble than physically move everything closer as it's easier to do.

As to whether or not you're overdoing it, it really comes down to whether or not you are having problems.  Most wireless mics have some sort of RF meter on them and one can usually get a pretty good idea of performance that way.  Whenever possible we also try and do a walk test before wiring talent or making a boom wireless so we can make an educated decision about which frequencies have the best performance and whether or not we need to move closer.  But if it's working well from the cart position, I usually have enough else to do that fixing unbroken things falls pretty low on the priority list.

Regards,

Noah Timan

Yeah we do all that too.  But in downtown SF or near the water every inch of proximity seems to help.  (So many RF squatters!)

I think I need some kind of clamp arrangement that will allow me to mount the stand on the cart, then pull it off w/o disconnecting--I think some of you are doing this already  (Darrren?).

thanks

Philip Perkins

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  • 3 weeks later...

I have a 12' antenna mast mounted on the main cart with a Remote Audio antenna bar. This holds four Lectro folding dipoles (two for wires, two for T1 transmitters). i also keep a Lectro log periodic on a Bogan Magic Arm with a 30' cable to quickly throw up when needed. I find myself needing it more and more these days.

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From a boom op's perspective,

as soon as we (myself and mixer) hear anything remotely sounding like RF interference, we are quickly moving the receivers closer to the transmitters, and when you're in the heat of battle, it's nice to have a cart with a receiver already attached to a 30' coil hanging there ready to go.

This reminds me of another recent post where someone mentioned politics on the set regarding quality of sound vs. keeping the finger of delay from pointing at our department. We don't want to hold up production, but still we want the best sound possible(the discussion: cable vs. wireless).

Therefore, maybe the little (to most people in the listening audience) lossy sound from a thirty foot cable is okay when compared to the minute and a half to move the sound cart or attach a run. A minute and a half can seem like forever when there are eighty people looking at you waiting to shoot.

Nothing is more satisfying than the AD catching us doing something unplanned and asking "how much time do you need?" and we respond  (as we lay down that attached cable), "don't wait for us, we're ready to go."

There are legitimate concerns over losing signal quality with extended cables. I have heard extreme differences from the same system with the antenae cable being the only thing changed. What I have noticed, the variable has not so much to do with the length of the cable as with the its quality (obviously you dont want to put a two hundred foot cable on your RX, I'm just talking about thirty feet or so). It would be worth it to spend the extra on the quality.

Doug

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Therefore, maybe the little (to most people in the listening audience) lossy sound from a thirty foot cable is okay when compared to the minute and a half to move the sound cart or attach a run. A minute and a half can seem like forever when there are eighty people looking at you waiting to shoot.

I think there is some confusion here -- making a longer antenna run (or using lossy cable) with the wrong kind of cable (or too much of it) does not cause lossy "sound", but it can cause lossy *RF performance*.  This means that you can lose antenna receiver signal gain (the reason you are moving the antenna in the first place), not that you lose audio fidelity per se.  The antenna being closer helps, but the tradeoff is the gain loss -- which in some situations, makes moving the antenna closer actually *degrade* rather than *improve* RF performance (if you use the wrong kind of cable or use an extremely long run).

nvt

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I'm curious, what kind of cables are wrong to use to extend the antennaes out from the cart?  I don't own antannaes but have used XLR cable to bring a Lectro 2xx receiver closer to set when I've been faced with very thick walls, metal, or just strange situations.

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I'm curious, what kind of cables are wrong to use to extend the antennaes out from the cart?  I don't own antannaes but have used XLR cable to bring a Lectro 2xx receiver closer to set when I've been faced with very thick walls, metal, or just strange situations.

That's a great solution, it's just time consuming and exposes your RX to damage on set.  To extend my log periodics I use 50 ohm coax, but not a whole lot of it (like 30').

Philip Perkins

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Guest Eric Lamontagne

Moving my antenna(s) a short distance is really only ever helpful when I want to get closer to line of sight, ie away from a wall/metal/concrete OR when I want to shift away from a strong local source (meaning close to my operating frequencies or powerful tx or both ***read: HD Viper systems).

I use a pair of Lectro powered filter amps (SNA) and a pair of LPDA directional antennas. 10ft 50ohm BNC on cart and 40ft extensions. I notice huge distance gain with the SNA inline. I notice specific directionality with the LPDA.

If I had more options with frequency agility I would not have discovered this 'radical' antenna aproach.

Once - in an emergency like only when my cable got cut, I have used a huge 50-100ft length of RG59 borrowed from the video dept and notice significant improvements in RF reception when placing the antennas away from camera/HD and towards the action. I would only assume this improvement occured because I moved the antennas away from RF interfierence and was using an amplifier which compensated for the ohm loss.

photos: http://jwsound.net/SMF/index.php?topic=387.0

Good Luck,

Eric Lamontagne

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