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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 => LAB: The Classic Live Audio Board => Topic started by: Keith Broughton on July 06, 2014, 01:26:06 PM
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I am going to try setting up an RF link to run main stage sound to a remote location.
Sennheiser G2 IEM transmitte to a helical antenna at the main stage.
Remote will be a log periodic ( no helical available) to mic receiver.
Given the frequency is clear and I have clear line of sight and good weather, what would be a fair estimate of the distance I could reliably cover?
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It would be far better to test and be positive at the location on the distance and signal strength.
The wireless mic receivers are stated as 300 ft ?? 150 to 400 ??
You will be limited by how much the transmitter will allow along with FCC legal questions.
You may want to ask around about a ham radio club and see what they can do for you and the signal?
More power available and good publicity for them.
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I am going to try setting up an RF link to run main stage sound to a remote location.
Sennheiser G2 IEM transmitte to a helical antenna at the main stage.
Remote will be a log periodic ( no helical available) to mic receiver.
Given the frequency is clear and I have clear line of sight and good weather, what would be a fair estimate of the distance I could reliably cover?
I would try first with a pair of LPDA paddles. There is no real advantage to the helical when you can set up the polarity of both the send and receive antennas. Get them up high and keep them both vertical or both horizontal.
How far do you need to go?
Mac
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Ditto what Mac said about making all antennas paddles - you lose a little bit when you go from helical to linear polarization, and with a fixed situation you control the polarization angles instead of things being moved around by performers.
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There is no real advantage to the helical when you can set up the polarity of both the send and receive antennas.
What's a few dB between friends?
All antenna discussion aside, the G2 transmitter is only about 30mW and won't get you fantastic distances even with line of sight between directional antennas. My estimate with a single helical and paddle is 850ft, +/-50ft.
Edit: given the right conditions...
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what would be a fair estimate of the distance I could reliably cover?
the G2's can go 1000 ft under the right conditions and antennas. Even at 30mW :-) i say go for it and let us know how it works out.
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I am going to try setting up an RF link to run main stage sound to a remote location.
Sennheiser G2 IEM transmitte to a helical antenna at the main stage.
Remote will be a log periodic ( no helical available) to mic receiver.
Given the frequency is clear and I have clear line of sight and good weather, what would be a fair estimate of the distance I could reliably cover?
Hi Keith,
I did the math for you, using a prototype of my soon-to-be-released Android app that calculates RSSI estimates for the "big 3" wireless systems sold in USA.
These calculations are for a G2 system, as you described, in low power TX mode (10mW, for the sake of being conservative), with a paddle on one end and a helical on the other, and with 25ft. of low-loss cable on each. These results are for a theoretically perfect line-of-sight fixed link in open space. I would cut this estimate in at least half for real world.
The calculation results show 2250ft. to 2500ft. before the RSSI begins to drop below a Sennheiser's nominal 40dBμV.
You can see detailed results in the following screen shots:
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Hi Keith,
I did the math for you, using a prototype of my soon-to-be-released Android app that calculates RSSI estimates for the "big 3" wireless systems sold in USA.
These calculations are for a G2 system, as you described, in low power TX mode (10mW, for the sake of being conservative), with a paddle on one end and a helical on the other, and with 25ft. of low-loss cable on each. These results are for a theoretically perfect line-of-sight fixed link in open space. I would cut this estimate in at least half for real world.
The calculation results show 2250ft. to 2500ft. before the RSSI begins to drop below a Sennheiser's nominal 40dBμV.
You can see detailed results in the following screen shots:
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I am going to try setting up an RF link to run main stage sound to a remote location.
Sennheiser G2 IEM transmitte to a helical antenna at the main stage.
Remote will be a log periodic ( no helical available) to mic receiver.
Given the frequency is clear and I have clear line of sight and good weather, what would be a fair estimate of the distance I could reliably cover?
I did exactly the same thing a few weeks ago using G3's, a helical and a log periodic, and had no issues with the 500' or so I was shooting for.
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I did exactly the same thing a few weeks ago using G3's, a helical and a log periodic, and had no issues with the 500' or so I was shooting for.
I was thinking about the fact that it would probably be better with the LPDA antennas at both ends as polarity would be fixed.
500' would be the real world distance so it looks like a go.
We will run XLR as well, just to have backup.
BTW...that app looks killer!
Thanks for the responses. Will post results.
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...using a prototype of my soon-to-be-released Android app that calculates RSSI estimates for the "big 3" wireless systems sold in USA.
Looks great! Any hope of an iOS version? (Someone had to ask)
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Looks great! Any hope of an iOS version? (Someone had to ask)
Hi Jordan,
I kind of expected that question to come up. ;)
I've researched it, and the folks at Apple make developers jump through hoops and pay some significant fees for the privilege of running on their platform. However, if the Android version is successful and shows promise, and the effort and cost required to go iOS appears recoverable, I'll do it.
Don't hold your breath, though! I'm no coder and my development pace is very, very slow.
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I was thinking about the fact that it would probably be better with the LPDA antennas at both ends as polarity would be fixed.
500' would be the real world distance so it looks like a go.
We will run XLR as well, just to have backup.
Wait wait...
if you're running XLR as a backup, why would you even bother with the wireless link?
am I missing something here?
I wish I remembered who said it first, but the quote goes something like "you can spend thousands of dollars on the best wireless available and it will be *almost* as good as a cable"
Jason
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Wait wait...
if you're running XLR as a backup, why would you even bother with the wireless link?
am I missing something here?
I wish I remembered who said it first, but the quote goes something like "you can spend thousands of dollars on the best wireless available and it will be *almost* as good as a cable"
Jason
my thoughts exactly. If you are running copper, why deal with RF?
- Tony Williams
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I understand - I've heard that from others, too.
Best of luck with it!
I'm always looking for tools like that to add to my arsenal...
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my thoughts exactly. If you are running copper, why deal with RF?
- Tony Williams
My thoughts are along the same lines - I don't care what anyone says: as long as a wired connection is a viable option, I'll pursue that first.
I had an event a few months ago that involved getting RF from outside in a tent to a set of speakers inside a building. I spec'd certain gear, but was only given some of it to complete the task. A Shure PSM1000 unit with matching RX units, but no LPDAs for TX or RX antennas or the ability to remote the antennas. So...I got everything as close to line-of-sight as possible and told the people involved what might happen (dropouts, loss of fidelity, etc.) and they were okay with it for that particular situation (background/area music...low volume with lots of people yakking around).
All that said, it would have been much simpler (and more reliable) to run an XLR or two - and it would have been cheaper, too.
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It's worth the time to use the wireless link in a real-time, non-critical situation. If in the future the wireless option becomes necessary, you'll have had a free trial run under your belt.
Also...redundancy.
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At what range of misalignment between RX/TX LPDAs do they become unmatched polarity?
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I am going to try setting up an RF link to run main stage sound to a remote location.
Sennheiser G2 IEM transmitte to a helical antenna at the main stage.
Remote will be a log periodic ( no helical available) to mic receiver.
Given the frequency is clear and I have clear line of sight and good weather, what would be a fair estimate of the distance I could reliably cover?
read this Shure article: Point - Point RF (http://shure.custhelp.com/app/answers/detail/a_id/3196)
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At what range of misalignment between RX/TX LPDAs do they become unmatched polarity?
Hi Jim,
Polarization orientation angle mismatch losses in dB are roughly as follows:
Circular to linear -3
RHCP to LHCP -∞
0° (aligned) -0
15° -0.3
30° -1.25
45° -3.01
60° -6.02
75° -11.74
90° (orthogonal) -∞
As is the case in many RF calculations, these are valid for free space links, in a theoretically perfect environment. It doesn't account for any of the multipath losses (and gains) that we observe in the real world. We will almost never see a perfect -∞ null in an orthogonal system on Earth, since many reflected paths will exist, and reflections alter signal polarization angle. At least one path will almost surely be measurable at the RX antenna.
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Hi Jim,
Polarization orientation angle mismatch losses in dB are roughly as follows:
Circular to linear -3
RHCP to LHCP -∞
0° (aligned) -0
15° -0.3
30° -1.25
45° -3.01
60° -6.02
75° -11.74
90° (orthogonal) -∞
As is the case in many RF calculations, these are valid for free space links, in a theoretically perfect environment. It doesn't account for any of the multipath losses (and gains) that we observe in the real world. We will almost never see a perfect -∞ null in an orthogonal system on Earth, since many reflected paths will exist, and reflections alter signal polarization angle. At least one path will almost surely be measurable at the RX antenna.
This may be a master of the obvious comment. I have mentioned I am a network/RF engineer for my "real job": Heavy RF, back in the day TV and FM broadcast then cellular. As I continue to understand the science of acoustics the math is the same.
When you start talking about mixing drivers at different phase angles to control audio propagation the same beam steering principals belong to RF. If a RX has a crappy front end changing the antenna polarization can drop the noise floor significantly.
Likewise a direction antenna with gain has no input power so it makes gain my "squeezing" one side of the pattern and adding the energy to the other.
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Topic swerve sorta...
Am I to understand that the G2 & G3 systems are each compatible between the wireless mic receivers and the IEM transmitters (assuming frequency matching)?
Most of the Shure systems are not so this may be the catalyst for me to add some Sennheiser gear.
Sent from my iPad using Tapatalk HD
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Topic swerve sorta...
Am I to understand that the G2 & G3 systems are each compatible between the wireless mic receivers and the IEM transmitters (assuming frequency matching)?
Most of the Shure systems are not so this may be the catalyst for me to add some Sennheiser gear.
Sent from my iPad using Tapatalk HD
Yes, you can transmit from Evolution G1/2/3 and 2000 IEM transmitters to Evolution G1/2/3 and 2000/2050+3732(in HDX mode) receivers. Just set the transmitter to mono, and turn off pilot tone on the receiver.
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Yes, you can transmit from Evolution G1/2/3 and 2000 IEM transmitters to Evolution G1/2/3 and 2000/2050+3732(in HDX mode) receivers. Just set the transmitter to mono, and turn off pilot tone on the receiver.
Thanks. Very cool.
Sent from my iPad using Tapatalk HD
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Wait wait...
if you're running XLR as a backup, why would you even bother with the wireless link?
am I missing something here?
I wish I remembered who said it first, but the quote goes something like "you can spend thousands of dollars on the best wireless available and it will be *almost* as good as a cable"
Jason
It was a chance to experiment while I had a backup rather than try it on a "mission critical" situation.
Wouldn't you rather experiment in a situation where a failure isn't an issue?
It's my time and effort....
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It's worth the time to use the wireless link in a real-time, non-critical situation. If in the future the wireless option becomes necessary, you'll have had a free trial run under your belt.
Also...redundancy.
Give the man a cigar :)