Hello all, one of our in-ear RF channels seems to drop out more than the others. We have seven channels, using Shure PSM900 systems. They are combined with a Shure PA821A combiner through 50 ft. of RG59 tothe antenna. The measured loss of the coax (with my service monitor) is 4.5 dB. We are using a Professional Wireless helical transmit antenna 50 ft. max from the talent on stage.
The user of the monitor in the 470 mc. range complains more about dropouts than the other six users which are between 598 and 626 mc. We have coordinated all in-house frequencies using Wireless Workbench, and included any active TV channels and anything else I can think of. I understand that some users may complain quicker than others about problems.
I took a long listen to the offending IEM receiver during rehearsal Tuesday night and found only a couple of random drops. They were hard to replicate a second time as far as trying to find the exact physical location. The next day I again listened to that channel, with no modulation this time, and can carefully find several very small areas where the signal gets noisy, and with careful movement will completely close the squelch.
Such is the nature of multipath, I know. I just would not expect to experience it's effects so close to the transmit antenna. I have checked all seven channels for proper RF output level, along with the output of the combiner to the antenna. All measurements are what I would expect. I have listened carefully to the problematic receiver for interference present while it is at the point of weakest signal, just before the squelch closes, and found little if anything. A spectrum scan with a number of mics and all IEMs operating shows nothing not expected, although I know that will not see products generated within equipment. A spectrum scan with all transmitters off also shows nothing not expected.
The one 470 mc. receiver seems to be the worst, but I can find slightly noisy multipath areas on stage with the other receivers too; it seems to be just a matter of degree.
So what is the 'normal' experience on stages. Is it expected that there may be the occasional IEM dropout with a setup such as ours (not using diversity receivers)? Is perfection within 50 ft. of the boresight of the antenna too much to ask? Is there something I have not checked?
Thanks!
Laryn
The user of the monitor in the 470 mc. range complains more about dropouts than the other six users which are between 598 and 626 mc. We have coordinated all in-house frequencies using Wireless Workbench, and included any active TV channels and anything else I can think of. I understand that some users may complain quicker than others about problems.
I took a long listen to the offending IEM receiver during rehearsal Tuesday night and found only a couple of random drops. They were hard to replicate a second time as far as trying to find the exact physical location. The next day I again listened to that channel, with no modulation this time, and can carefully find several very small areas where the signal gets noisy, and with careful movement will completely close the squelch.
Such is the nature of multipath, I know. I just would not expect to experience it's effects so close to the transmit antenna. I have checked all seven channels for proper RF output level, along with the output of the combiner to the antenna. All measurements are what I would expect. I have listened carefully to the problematic receiver for interference present while it is at the point of weakest signal, just before the squelch closes, and found little if anything. A spectrum scan with a number of mics and all IEMs operating shows nothing not expected, although I know that will not see products generated within equipment. A spectrum scan with all transmitters off also shows nothing not expected.
The one 470 mc. receiver seems to be the worst, but I can find slightly noisy multipath areas on stage with the other receivers too; it seems to be just a matter of degree.
So what is the 'normal' experience on stages. Is it expected that there may be the occasional IEM dropout with a setup such as ours (not using diversity receivers)? Is perfection within 50 ft. of the boresight of the antenna too much to ask? Is there something I have not checked?
Thanks!
Laryn