Wireless RF Issues

We are having issues with RF dropouts with our wireless mics. We are running
3 ULXD4Q G50 band (for a total of 12 channels)
7 AudioTechnica 3000 series D band
2 AudioTechnica 3000 series C band
2 Audio technica antenna distribution D band
2 Shure SLX G5 Band
2 Acacia Audio IMCTU12(655-679)

Heres how this is all setup:
We have 2 Audiotechnica Paddle antennas with their antenna outs feeding 2 AudioTechnica Active Antenna Splitters. One of the outputs of the antenna splitter feeds one of the audiotechnica antenna distros and the cascade output of that distro feeds the input of the next distro. The other output of the antenna splitter feeds The Shure ULXD's using the input of the first one and the cascade out to the in of the next one. The extra audio technica and the 2 Shure six's and the acacia audio are all fed just using the supplied whip antennas and I have no problem with those.

The problem:
We are getting way too weak RF signal on most mics. It is causing dropouts. I have tried using different antennas and not using the active antenna splitter and both have not helped.

If anyone has any suggestions it would be awesome. Our show is on Friday:(.
 

Attachments

  • IMG_2562.JPG
    IMG_2562.JPG
    148 KB · Views: 319
  • IMG_2561.JPG
    IMG_2561.JPG
    93.2 KB · Views: 315
  • IMG_2563.JPG
    IMG_2563.JPG
    52 KB · Views: 330
How far away from the stage are the paddles? Are the paddles active or passive? The picture of the back of the rack unfortunately isn't all too helpful as I can't follow the cables with my hands! :( I know it seems obvious, but are the frequency ranges of all the distro units in use compatible with all the receivers (ie, are you using wideband distros)?

As a baseline test (before you reconfigure the whole setup) - connect the paddle antennas directly to a known "trouble" system (singular receiver) that you're having issues with. Then, connect the paddles to a known "good" system. Do the issues go away or remain the same? Essentially, let's bypass all the distro units and see if this is a pure RF coverage/interference issue (which would be a whole different can of worms, as I assume a frequency coordination has already been completed) or something in the distro setup.
1: ANT-A--->RX-A
ANT-B--->RX-B

If the above test goes well, feed a distro directly with the antennas and test the results of the immediate 4 receivers connected to the distro that is being fed directly by the antennas.

If I'm understanding your setup correctly, is this what it looks like now? (EDIT: I just looked over the photos again, I'm guessing that I missed something somewhere, or i'm missing a device (See my note below regarding the splitters vs distros). Try configuring as below (you'll lose 4 receivers, though) and let's see what the results are.)

2: ANT-A--->DISTRO-1 INPUT A--->RX1A/RX2A/RX3A/RX4A
ANT-B--->DISTRO-1 INPUT B--->RX1B/RX2B/RX3B/RX4B
DISTRO-1 CAS A--->DISTRO-2 INPUT A
DISTRO-1 CAS B--->DISTRO-2 INPUT B

DISTRO-2 Outputs feed RX 5-8 respectively. If you have a cascade output on DISTRO-2, feed #9 receiver.

If this causes issues, it would lead me to believe there's a frequency compatibility issue somewhere within the equipment.

The active antennas splitters you describe - are those the distribution units we're observing in the second photo, or is there some other device between the first distro and the antennas? (Based on the cable size I'm seeing, I'm guessing the active splitters you're describing are the rack mounted distro units.) If my assumption is correct about the heavier cable being the antenna feed, I believe your second distro should be connected via those empty "cascade" ports next to the antenna inputs (though that wouldn't explain why the receivers connected directly there would have issues).
 
A few things set off alarm bells for me. First off, some of these systems are in the 600 MHz band. With the TV repack going on, you could be getting nailed by new cell or TV signals. Spectrum that used to be quiet is getting lit up right now. Even if they are on different frequencies, strong signals can cause receiver desensitization. The >600 MHz equipment needs to go away now, and will be illegal in mid 2020.

You didn't provide model numbers, but you indicate the two, main antenna DAs are frequency tuned for band D. If so, that means it filters out signals outside of that band. Other frequency ranges are are not passed through by the DA. Receivers outside band D will need different antenna systems.

And finally, that's a large number of channels in use. As the number of frequencies in use grows, the chance for intermodulation products grows exponentially. Intermod products are mathematical mixes of the signals. That means the frequency selection has to be done very carefully with a software program, such as Wireless Workbench. The software will pick combinations of frequencies that don't cause harmful mixes or active TV channels.

You have a fairly big mess on your hands with a show on Friday. I suggest renting a full system that has been set up and frequency coordinated for your location. After you get through the show, you'll have time to methodically sort out the problems.
 
A few things --
1. If you didn't coordinate, then this is going to be a mess. I just ran a Transmitter report for a Northern VA ZIP Code, and while you can make your entire system work, if you were just guessing on frequencies you're going to get nailed. Channel 33-38 are no good, as are 40, 42, 44, 46, 48, and 50.

2. You have no reliable way to coordinate your Acacia wireless, as the manufacturer does not provide a frequency table.

Anyhow, here is a very tiny, but still readable screenshot of a valid coordination for your wireless that has taken intermod into account. The only thing it doesn't plan on is the Acacia stuff. If you didn't actively coordinate your 3000 Series D Band, I'm sure they were getting absolutely killed by interference.


Screen Shot 2018-04-21 at 3.25.18 PM.png
 
T- Mobile 600 mHz service in Morgan and Berkeley counties in VA is already hot and running.

New map of T-Mobile roll outs here
 
and last but not least, you probably know this already, but the paddle antennas should be 60 to 90 degrees off vertical axis with each other in order to get true diversity as the RF has only one axis polarity and if both are just vertical, you will have dead zones as the packs rotate as they are being moved.
That said, I tend to agree that the biggest problem is that the 600mhz band is pretty much trashed now that the changes took place.
 
Thanks for all the replies! I figured the problem was how many units I was cascading together. I fixed the problem by just using the included whip antennas for the ulxd's. I got the same reception with the whip antennas on 1mw power then I was getting with the 20mw power through the paddles. I have been using WWB to frequency coordinate. Yep those acacias are annoying, I have extra AT's on hand but no extra elements for them, so have to use the acacias(or get really good at soldering). 600 MHZ mics are getting replaced for us soon with more ULXD's :).
 
Thanks for all the replies! I figured the problem was how many units I was cascading together. I fixed the problem by just using the included whip antennas for the ulxd's. I got the same reception with the whip antennas on 1mw power then I was getting with the 20mw power through the paddles. I have been using WWB to frequency coordinate. Yep those acacias are annoying, I have extra AT's on hand but no extra elements for them, so have to use the acacias(or get really good at soldering). 600 MHZ mics are getting replaced for us soon with more ULXD's :).

I thought something looked odd about the empty cascade ports on the first DA with the antenna feeds. Hope your show goes well.
 

Users who are viewing this thread

Back