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Author Topic: network hub for Senn. G3  (Read 2502 times)

Jens Palm Bacher

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Re: network hub for Senn. G3
« Reply #10 on: November 14, 2012, 03:34:35 pm »

Why is there no mic transmitter on? The RF level of background noise is meaningless without a reference to what the mic transmitter is putting out. The "level" on the vertical axis does not represent normal RF type levels, which would have noise in the -100dB to -80dB range and mic transmitters in the -60dB to -20dB range. What does that scale represent?
Mac
A competent RF tech would easily spot that the Sennheiser G3 and 2000 systems use dBuV in their rf signal strengt metres, why is that not normal rf type levels?

The top of the scale is 40dBuV = 100uV = -67 dBm in a 50 ohm system.

I agree that the scale should go higher, at least 50 dBuV
« Last Edit: November 14, 2012, 03:46:17 pm by Jens Palm Bacher »
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Mac Kerr

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Re: network hub for Senn. G3
« Reply #11 on: November 14, 2012, 03:56:17 pm »

It looks to me like WSM is using 'absolute numbers' , albeit they may not be referenced to some existing standard, they still appear consistent between all graphs. 

Therefore using these graphs to compare the noise (relative to the fixed squelch setting) introduced by the three different AP devices , and to compare the different physical positions (console, floor, next room) appears to be a valid analysis.

With the level of the mic transmitter off scale at the top of the chart there is no way to compare that level to the noise level. There is always noise at some level, what is important is how far above the noise the desired signal is.

It is always good practice to keep your RF mic receivers separated from other equipment that has RF output. This includes both intentional output, like your AP, or IEM transmitters, as well as unintended output, like the spurious output of other devices like computers and other electronics. If you have the AP in the rack with the receivers you should have remote antennas for the mics. Better yet you should also have a remote location for the AP that connects with cable to a small basic switch in the rack.

If as Jens mentions, the 40dB is really representative of -67dBm, that puts the noise level in your first graph (highest noise level) at about 20dB below that, or -87dBm, a slightly high, but not unreasonable noise level considering you are measuring near a transmitter and a digital console.

Whether or not that is a workable noise level depends on what the RF level of the mic is in normal operating conditions.

Mac
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Matt Tudor

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Re: network hub for Senn. G3
« Reply #12 on: November 14, 2012, 05:54:30 pm »

Hi,

Racking up our Senn. G3 receivers into 4-way racks I'd like to connect the ethernet management ports into a 5-way hub (1 in, 4 out) for quick setup.. and ideally one with a built in wireless AP like the TP-Link TL-WR743 or similar.

Should I be concerned about RF noise? .. is placing an ethernet switch or AP very close to a bunch of receivers likely to cause issues?

1  -has anyone had problems?
2 - any recommended make / models - We use Apple Airport Express in back of our M7's & LS9's for the audio port.. but obviously need something with at least 5 ports for a 4-way Senn RX rack... would a metal-cased unit like the Netgear Pro range help reduce noise?
3 - should i steer clear, use longer UTP cables and have a simple hub sat a few feet away?

Thanks

.gh

I have a wireless rack including 4 300G3 units with an ASA-1 splitter. I put a small 5 port Belkin router in the back of the rack. The antennas for the splitter are the little whips that came with it, mounted on the front of the rack. Never had a problem. 4 short Ethernet runs from the router to the receivers, 1 short run to an EtherCon jack on the back of the rack to get to the outside world.
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Mac Kerr

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Re: network hub for Senn. G3
« Reply #13 on: November 14, 2012, 06:01:32 pm »

I put a small 5 port Belkin router in the back of the rack. The antennas for the splitter are the little whips that came with it, mounted on the front of the rack. Never had a problem. 4 short Ethernet runs from the router to the receivers, 1 short run to an EtherCon jack on the back of the rack to get to the outside world.

That's not the same as the wireless access point Mark is dealing with.

Mac
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Jason Glass

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Re: network hub for Senn. G3
« Reply #14 on: November 15, 2012, 11:39:03 am »

A competent RF tech would easily spot that the Sennheiser G3 and 2000 systems use dBuV in their rf signal strengt metres, why is that not normal rf type levels?

The top of the scale is 40dBuV = 100uV = -67 dBm in a 50 ohm system.

I agree that the scale should go higher, at least 50 dBuV

A competent RF Tech doesn't make assumptions based on the look of the scale.  For example: WinRadio's SA window shows the same scale reference as WSM, yet when you look in the WinRadio manual, it says, "dB above the noise floor of the hardware."  If the user made the same assumption you described, his measurements would be inaccurate.
« Last Edit: November 15, 2012, 11:42:04 am by Jason Glass »
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Jens Palm Bacher

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Re: network hub for Senn. G3
« Reply #15 on: November 15, 2012, 02:06:24 pm »

A competent RF Tech doesn't make assumptions based on the look of the scale.  For example: WinRadio's SA window shows the same scale reference as WSM, yet when you look in the WinRadio manual, it says, "dB above the noise floor of the hardware."  If the user made the same assumption you described, his measurements would be inaccurate.
I didnt guess it by looking at the scale, but by seeing the tech data, that show the squelch to be adjustable from 5-25 dBuV, which corresponds with how the squelch treshold is displayed on the meter.
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Jason Glass

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Re: network hub for Senn. G3
« Reply #16 on: November 15, 2012, 06:59:20 pm »

I didnt guess it by looking at the scale, but by seeing the tech data, that show the squelch to be adjustable from 5-25 dBuV, which corresponds with how the squelch treshold is displayed on the meter.

I humbly stand corrected.  ;)
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