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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Wireless and Communications => Topic started by: Justin Goodman on December 17, 2018, 01:38:52 PM

Title: True diversity or frequency diversity?
Post by: Justin Goodman on December 17, 2018, 01:38:52 PM
Application is wedding ceremonies ... question essentially boils down to - for RF reception - whether I'm better off with a (1) bodypack transmitter and a true diversity receiver (UHF-R) or (2) bodypack transmitters (on the same person) and switching diversity receiver (ULX-D) with the receiver's dual bodypack diversity enabled (basically auto-switching over to backup tx/frequency if it loses one).

Other caveat/consideration is of course that I'm often working with bodypack on a backside/hip of an officiant (try for jacket pocket where possible, but some of these guys wear just a shirt under robes or similar, and most women wear dresses) while I'm 200'+ away with the entire crowd between me and officiant. UHF-R having the higher power output puts my mind at ease a bit there. 

Due to wedding planners' general lack of reasonableness/desire to preserve a super wide angle photo shot, I usually end up with both LPDAs mounted to the same stand (vertically polarized 7' or so high and horizontally polarized around 5' up the stand). 

I've never actually experienced any drop outs, so this isn't necessarily born from a desire to "fix" anything ... but I do have another (install) application where I can use this UR4D (and where I only need 2 channels) and I have a ULXD4Q I could put into wedding ceremony duty (using 2 channels/BPs for officiant).  Really just want to make sure I'm not making the wedding system worse...

Mock up of typical ... usually 150-250' between me and the officiant:
Title: Re: True diversity or frequency diversity?
Post by: Luke Geis on December 17, 2018, 04:50:43 PM
I have two words for you: RF Venue

They make a flat antenna that can be placed under a lecturn or even carpet that sits flat on the ground. It is the answer you seek. You can use the RF Venue and a Paddle if you want. The only kicker is needing a long 50ohm cable to get from your Rack to the Hoopa or ceremony. 
Title: Re: True diversity or frequency diversity?
Post by: Justin Goodman on December 17, 2018, 05:00:38 PM
I have two words for you: RF Venue

They make a flat antenna that can be placed under a lecturn or even carpet that sits flat on the ground. It is the answer you seek. You can use the RF Venue and a Paddle if you want. The only kicker is needing a long 50ohm cable to get from your Rack to the Hoopa or ceremony.

Have thought about a spotlight before -- certainly would install one if I was purpose building a venue and could bury the cable or run it in-wall. 300' of coax is definitely more trouble than I'm looking for. I actually also use an IEM and battery powered speaker (and sometimes a Yeti powerstation if I have no building to draw power from), so I'm 100% wireless.  Coiling up 300' of coax that is thick enough for a run that long is a definite step backwards in that regard, though I so wish it weren't. 
Title: Re: True diversity or frequency diversity?
Post by: Jordan Wolf on December 17, 2018, 05:48:44 PM
Application is wedding ceremonies...
Justin,

If you can get the receivers closer to the stage, the coax run won't have to be that long and the cable as thick.

Have you considered RF over Fiber (also available from RF Venue)? If you do enough of these events to warrant such a specialized solution, it may be time to buy into that kind of solution.
Title: Re: True diversity or frequency diversity?
Post by: Brian Jojade on December 17, 2018, 06:13:50 PM
The advantage of the dual bodypack is that you have a full backup of everything ready to go.  Backup mic, backup transmitter, etc.  You could accomplish almost the same thing by simply using 2 of any wireless system and just having 2 channels on your mixer and manually turning on one if the other fails. I'm not sure if the auto failover feature would work on the ULX-D system if say the mic were to come unplugged for some reason.

I've been using the QLX-D systems which is the baby to the ULX-D.  When using a pair of Audio Technica ATW-A49 antennas (way cheaper than the Shure counterparts...) I've never had a dropout concern, even with occasionally using them at distances over 500' outdoors. Usually, I just end up mounting the paddles on stands right next to the receivers with 15' patch cables.

Now, that's working in relatively clear RF space.  If you're in a congested RF area, then the rules change a bit, and getting the antenna as close as possible can help.  If you're concerned that someone in the next room might turn on another transmitter in the same frequency space, having the 2nd bodypack on a separate frequency is going to give you the ability to keep functioning.
Title: Re: True diversity or frequency diversity?
Post by: Justin Goodman on December 30, 2018, 07:43:42 PM
Thanks for the answers thus far. I would actually probably use the AXT cable to split 1 mic into 2 bodypacks.  Officiants are a fickle bunch ... 2 bodypacks will be enough of a fight.

I guess what I'm asking is that as a matter of signal stability/RF only, is option 1 or 2 more "dropout resistant?"

1. 2 ULXD transmitters and 1 ULXD receiver with antenna switching/predictive diversity. I could orient the bodypacks on left and right back hips/belt to try and achieve quasi line of sight in many cases (or at least not "shoot" directly though the meatiest part of a person), but ultimately I may be trying to transmit 200-300' from behind a person with maximum 20mw and very few RF-reflective surfaces in an open outdoor environment. 

2. 1 UHF-R transmitter and 1 UHF-R receiver with true diversity. Benefit here is being able to crank up the output power to 50-100mw outdoors and obviously true diversity.