standing waves in wireless sys
in [Live Sound]
|
Prev: Comperssor Help
Next: Comperssor Help
From: Ty Ford on 26 Jun 2010 10:38 On Sat, 26 Jun 2010 10:21:28 -0400, alex wrote (in article <4c260cea$0$31379$4fafbaef(a)reader1.news.tin.it>): > Il 26/06/2010 16.16, Phil Allison ha scritto: >> "alex" >>> >>> can two parallel walls generate a standing wave on the carrier of a >>> wireless system and affect the reception of the signal, just like in >>> sound? >>> >> >> ** The reflectivity of a solid wall to RF signals in the VHF /UHF band is >> not nearly so strong as it is for sound waves - so the behaviour is not the >> same. >> >> Certainly, a radio mic's signal can bounce off a wall and arrive at the >> receiver out of phase with the direct signal from the same transmitter >> causing reception to almost disappear - diversity receivers using twin >> antennas and RF stages are designed to defeat this phenomenon. >> >> >> >> .... Phil >> >> > thanks phil, > but in the situation described above i had shure diversity system that > almost refused to work. > > alex Last time I had that happen some of the people I tried to mic had not turned off their personal communications devices. I had walk tested the mics to 50 feet or so before these folks showed up. Range went to 2 feet when they were there then went back to 50 feet when they left. Regards, Ty Ford --Audio Equipment Reviews Audio Production Services Acting and Voiceover Demos http://www.tyford.com Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA
From: bob u on 26 Jun 2010 10:46 On 6/26/2010 9:21 AM, alex wrote: > Il 26/06/2010 16.16, Phil Allison ha scritto: >> "alex" >>> >>> can two parallel walls generate a standing wave on the carrier of a >>> wireless system and affect the reception of the signal, just like in >>> sound? >>> >> >> ** The reflectivity of a solid wall to RF signals in the VHF /UHF band is >> not nearly so strong as it is for sound waves - so the behaviour is >> not the >> same. >> >> Certainly, a radio mic's signal can bounce off a wall and arrive at the >> receiver out of phase with the direct signal from the same transmitter >> causing reception to almost disappear - diversity receivers using twin >> antennas and RF stages are designed to defeat this phenomenon. >> >> >> >> .... Phil >> >> > thanks phil, > but in the situation described above i had shure diversity system that > almost refused to work. > > alex And you had an antenna manifold with remote antenna paddles on stands in different locations? Having two antennas 6" apart does not solve many issues if you left them on the receivers in stock out of the box form. bob
From: Ron on 26 Jun 2010 11:04 On 26/06/2010 15:38, Ty Ford wrote: > On Sat, 26 Jun 2010 10:21:28 -0400, alex wrote > (in article<4c260cea$0$31379$4fafbaef(a)reader1.news.tin.it>): > >> Il 26/06/2010 16.16, Phil Allison ha scritto: >>> "alex" >>>> >>>> can two parallel walls generate a standing wave on the carrier of a >>>> wireless system and affect the reception of the signal, just like in >>>> sound? >>>> >>> >>> ** The reflectivity of a solid wall to RF signals in the VHF /UHF band is >>> not nearly so strong as it is for sound waves - so the behaviour is not the >>> same. >>> >>> Certainly, a radio mic's signal can bounce off a wall and arrive at the >>> receiver out of phase with the direct signal from the same transmitter >>> causing reception to almost disappear - diversity receivers using twin >>> antennas and RF stages are designed to defeat this phenomenon. >>> >>> >>> >>> .... Phil >>> >>> >> thanks phil, >> but in the situation described above i had shure diversity system that >> almost refused to work. >> >> alex > > Last time I had that happen some of the people I tried to mic had not turned > off their personal communications devices. I had walk tested the mics to 50 > feet or so before these folks showed up. Range went to 2 feet when they were > there then went back to 50 feet when they left. > > Regards, > > Ty Ford I've found that Blackberry devices can trash the agc on some Sennheiser mikes leading to (I presume) the mike seemingly increasing it's own gain into feedback. Ron
From: alex on 26 Jun 2010 11:14 Il 26/06/2010 16.46, bob u ha scritto: > On 6/26/2010 9:21 AM, alex wrote: >> Il 26/06/2010 16.16, Phil Allison ha scritto: >>> "alex" >>>> >>>> can two parallel walls generate a standing wave on the carrier of a >>>> wireless system and affect the reception of the signal, just like in >>>> sound? >>>> >>> >>> ** The reflectivity of a solid wall to RF signals in the VHF /UHF >>> band is >>> not nearly so strong as it is for sound waves - so the behaviour is >>> not the >>> same. >>> >>> Certainly, a radio mic's signal can bounce off a wall and arrive at the >>> receiver out of phase with the direct signal from the same transmitter >>> causing reception to almost disappear - diversity receivers using twin >>> antennas and RF stages are designed to defeat this phenomenon. >>> >>> >>> >>> .... Phil >>> >>> >> thanks phil, >> but in the situation described above i had shure diversity system that >> almost refused to work. >> >> alex > > And you had an antenna manifold with remote antenna paddles on stands > in different locations? Having two antennas 6" apart does not solve > many issues if you left them on the receivers in stock out of the box form. > > bob yes, tried with and without antenna distibution system and moving antennas back and forth. Almost no change whatever i done. I tried also to move the receiver from the desk position to stage area. Still no effect. changing brand of system (thus freq range) solved. Outside the church no problem even at 70 meters distance. That sounded to me like a phase related problem on the carrier, because i was 100% sure no interference from other radio sources where there. Actors were dressed in costume and i'm sure they had no comm device at all. alex
From: Phil Allison on 26 Jun 2010 20:32
"alex" Phil Allison > "alex" >>> >>> can two parallel walls generate a standing wave on the carrier of a >>> wireless system and affect the reception of the signal, just like in >>> sound? >>> >> >> ** The reflectivity of a solid wall to RF signals in the VHF /UHF band is >> not nearly so strong as it is for sound waves - so the behaviour is not >> the >> same. >> >> Certainly, a radio mic's signal can bounce off a wall and arrive at the >> receiver out of phase with the direct signal from the same transmitter >> causing reception to almost disappear - diversity receivers using twin >> antennas and RF stages are designed to defeat this phenomenon. >> >> >> > thanks phil, > but in the situation described above ... ** Looks to me that you described nothing. .... Phil |