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Title: Extending range of Sennheiser EW100 radio mic
Post by: Gary Fitzpatrick on February 03, 2020, 02:20:17 PM
I have a church looking to increase the range of their Sennheiser EW100 handheld microphone.  I have attached a rough layout of the church with the location of the two existing aerials. The radio mic is a bit patchy down at the back of the church at the main doors. The church want to extend the coverage down to the back of the church for meeting funerals and Easter ceremonies. The existing antenna are half wave whips. Without adding an antenna splitter I am confined to passive antenna. Would either the A1031 or A2003 antenna provide much of an improvement?
Or would I be better installing an antenna splitter and installing an antenna booster be a better bet?

Cheers
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Russell Ault on February 03, 2020, 02:34:58 PM
I have a church looking to increase the range of their Sennheiser EW100 handheld microphone.  I have attached a rough layout of the church with the location of the two existing aerials. The radio mic is a bit patchy down at the back of the church at the main doors. The church want to extend the coverage down to the back of the church for meeting funerals and Easter ceremonies. The existing antenna are half wave whips. Without adding an antenna splitter I am confined to passive antenna. Would either the A1031 or A2003 antenna provide much of an improvement?
Or would I be better installing an antenna splitter and installing an antenna booster be a better bet?

How big is the space?

-Russ
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Ike Zimbel on February 03, 2020, 03:03:49 PM
I have a church looking to increase the range of their Sennheiser EW100 handheld microphone.  I have attached a rough layout of the church with the location of the two existing aerials. The radio mic is a bit patchy down at the back of the church at the main doors. The church want to extend the coverage down to the back of the church for meeting funerals and Easter ceremonies. The existing antenna are half wave whips. Without adding an antenna splitter I am confined to passive antenna. Would either the A1031 or A2003 antenna provide much of an improvement?
Or would I be better installing an antenna splitter and installing an antenna booster be a better bet?

Cheers
Hi Gary, The A-2003 has 4dB of gain, which should help. I would start with a pair of those. You definitely do NOT want to add an "antenna booster" as all that will do is raise your noise floor. All active antenna gain devices are intended to overcome cable losses, not to boost reception.
That said, how long are your antenna cables and what type are they?
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Keith Broughton on February 03, 2020, 04:25:26 PM
Hi Gary, The A-2003 has 4dB of gain, which should help. I would start with a pair of those. You definitely do NOT want to add an "antenna booster" as all that will do is raise your noise floor. All active antenna gain devices are intended to overcome cable losses, not to boost reception.
That said, how long are your antenna cables and what type are they?
A pair of A2003 antennas, pointing down the length of the room should work well.
Keep antenna cable runs short and use good quality cable.
As Ike said...don't use an "antenna booster". It doesn't replace a good antenna and cable solution.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 03, 2020, 04:45:35 PM
I don't get this. If using an antanna booster, wouldn't it just boost the signal from the receiving antenna with close to as much S/N ratio with what the antenna itself is picking up?
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: John Sulek on February 03, 2020, 05:14:57 PM
I don't get this. If using an antanna booster, wouldn't it just boost the signal from the receiving antenna with close to as much S/N ratio with what the antenna itself is picking up?

You want to keep the noise floor as low as possible for best performance especially as the tx/rx distance increases. The goal when adding an active device to the antenna feed is to have a net result of unity gain by matching the amount of active gain to the cable loss.

Try switching an active antenna from 0db or 3db of gain to 10db on a short (10m or less) cable and watch the rf meters on your receivers.
Previously "dark" meters start to show a bit of rf activity. That is the noise floor that you have just raised.
When you get to the fringe areas of reception...your transmit signal may get buried in the higher noise floor.

I'm sure others have a more eloquent explanation.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Don Boomer on February 03, 2020, 05:43:30 PM
Antenna boosting amps do not increase your range, they just increase the voltage. Your receiver doesn’t really care about voltage unless you are very high or very low. With all things operating under “normal” conditions what really keeps you on the air is your carrier to noise ratio. So if you use a line amp you boost both the intended signal and the unintended noise by the same amount (plus adding a small amount of extra noise and distortion as no amp is perfect). Your CNR actually will get a bit worse.

So usually range isn’t the actual issue. If we took your mics outdoors in the middle of a big field and there was no other interference present your mics would likely have a range of 600’. But when you bring them indoors you start having multipath problems plus whatever other interference is local.

Try switching to directional antennas (without builtin boosters) with good quality coax.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Gary Fitzpatrick on February 03, 2020, 07:10:27 PM
Antenna boosting amps do not increase your range, they just increase the voltage. Your receiver doesn’t really care about voltage unless you are very high or very low. With all things operating under “normal” conditions what really keeps you on the air is your carrier to noise ratio. So if you use a line amp you boost both the intended signal and the unintended noise by the same amount (plus adding a small amount of extra noise and distortion as no amp is perfect). Your CNR actually will get a bit worse.

So usually range isn’t the actual issue. If we took your mics outdoors in the middle of a big field and there was no other interference present your mics would likely have a range of 600’. But when you bring them indoors you start having multipath problems plus whatever other interference is local.

Try switching to directional antennas (without builtin boosters) with good quality coax.

Thanks everyone for the advise. The main aisle of the church is maybe 35m long and 15m wide.
I'm not sure of the coax, it was installed a number of years ago and at the minute running new coax may not be feasible. But I will install a pair of directional  antenna and try that first.

Gary
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Tim McCulloch on February 03, 2020, 07:18:09 PM
Gary, I'm not sure what hire shops are near Fermanagh, but consider renting the log-periodic (shark fin) antennae and see if that improves the result.  If you have a buddy in the RF world perhaps they have a TDS (time domain spectrometer) to analyze the coax for you.  TDS can show the distance to faults.

A former coworker's "day job" was installing ILS - instrument landing systems - at commercial airports.  If there was any compromise to the coax it would show up on the TDS, and ALL the RF components used in the installation had to be documented and certified as part of the install.  He showed me a "crushed" coax (stepped on) and an impedance bump cause by a kink in a cable.  This was over 25 years ago and I still remember seeing the display on the analyzer and thinking "this is waaay cool."
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Russell Ault on February 03, 2020, 10:51:46 PM
Thanks everyone for the advise. The main aisle of the church is maybe 35m long and 15m wide.
I'm not sure of the coax, it was installed a number of years ago and at the minute running new coax may not be feasible. But I will install a pair of directional  antenna and try that first.

Maybe it's just me, but if your antennas are already overhead (so line-of-sight is being maintained) I feel like 35m from RX to TX shouldn't be any problem on half-wave whips. Is the mic tuned to a clear frequency? Are the antennas actually half-wave? I'm sure I've seen those mics work reliably over that distance without any trouble, even on the stock whips attached directly to the TX.

-Russ
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 05, 2020, 01:20:28 PM
You want to keep the noise floor as low as possible for best performance especially as the tx/rx distance increases. The goal when adding an active device to the antenna feed is to have a net result of unity gain by matching the amount of active gain to the cable loss.

Try switching an active antenna from 0db or 3db of gain to 10db on a short (10m or less) cable and watch the rf meters on your receivers.
Previously "dark" meters start to show a bit of rf activity. That is the noise floor that you have just raised.
When you get to the fringe areas of reception...your transmit signal may get buried in the higher noise floor.

I'm sure others have a more eloquent explanation.

But.. Still don't get it..bummer. The same signal to noise ratio is still there? As it will boost every incoming signal with the same amount. The only "extra noise" would be from the booster unit itself due to design?

If I use a 10dB booster, then I'd boost "everything" by 10dB, also the Tx signal. But if that signal is crap then it will still be as crap with or without the booster, wouldn't it? One has raised the noise floor, but the Tx signal will be equally stronger at the receiver, but there's more noise (and also Tx) in the chain?
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Caleb Dueck on February 05, 2020, 03:22:05 PM
Maybe it's just me, but if your antennas are already overhead (so line-of-sight is being maintained) I feel like 35m from RX to TX shouldn't be any problem on half-wave whips. Is the mic tuned to a clear frequency? Are the antennas actually half-wave? I'm sure I've seen those mics work reliably over that distance without any trouble, even on the stock whips attached directly to the TX.

-Russ

Agreed, I've used a similar wireless (A-T 4k) hand held around 60m outdoor, line of sight, without issues.  The spectrum was pretty clear though, out in the country. 
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Ike Zimbel on February 05, 2020, 03:33:44 PM
But.. Still don't get it..bummer. The same signal to noise ratio is still there? As it will boost every incoming signal with the same amount. The only "extra noise" would be from the booster unit itself due to design?

If I use a 10dB booster, then I'd boost "everything" by 10dB, also the Tx signal. But if that signal is crap then it will still be as crap with or without the booster, wouldn't it? One has raised the noise floor, but the Tx signal will be equally stronger at the receiver, but there's more noise (and also Tx) in the chain?
While this is essentially correct logic, in practical terms it falls down because there is an upper limit to how much of your wanted signal you can use. So, what you are effectively doing is a) raising the noise floor and, b) limiting the dynamic range. For example, the LED's on a Shure AD top out at -70dB. If you have full bars, and add 10dB of gain, you are raising the noise floor by 10db, and while your signal is now -60dB, it's not really doing anything for you except putting you 10dB closer to an RF overload.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 05, 2020, 04:25:32 PM
While this is essentially correct logic, in practical terms it falls down because there is an upper limit to how much of your wanted signal you can use. So, what you are effectively doing is a) raising the noise floor and, b) limiting the dynamic range. For example, the LED's on a Shure AD top out at -70dB. If you have full bars, and add 10dB of gain, you are raising the noise floor by 10db, and while your signal is now -60dB, it's not really doing anything for you except putting you 10dB closer to an RF overload.

Thank you! Perfect! This was exactly the kind of answer I was looking for with my "teaspoon-question".

And just to ask one more. Shure has an OL LED for RF as far as I know. Sennys do not. I've not been able to see if im close of wherever I'm at for RF overload on Sennheiser G3. How do I see that, even in WSM?

In WSM I use the RF Level Recorder and walk around the coverage area, and look at the screen after the walk, I can see that the reception is in the ceiling of the graph, but I don't see if it has ever been overloaded.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Dave Garoutte on February 05, 2020, 04:46:45 PM
I have a church looking to increase the range of their Sennheiser EW100 handheld microphone.  I have attached a rough layout of the church with the location of the two existing aerials. The radio mic is a bit patchy down at the back of the church at the main doors. The church want to extend the coverage down to the back of the church for meeting funerals and Easter ceremonies. The existing antenna are half wave whips. Without adding an antenna splitter I am confined to passive antenna. Would either the A1031 or A2003 antenna provide much of an improvement?
Or would I be better installing an antenna splitter and installing an antenna booster be a better bet?

Cheers

Just double checking that they aren't 1/4 wave whips, which need a ground plane.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Mac Kerr on February 05, 2020, 08:15:31 PM
While this is essentially correct logic, in practical terms it falls down because there is an upper limit to how much of your wanted signal you can use. So, what you are effectively doing is a) raising the noise floor and, b) limiting the dynamic range. For example, the LED's on a Shure AD top out at -70dB. If you have full bars, and add 10dB of gain, you are raising the noise floor by 10db, and while your signal is now -60dB, it's not really doing anything for you except putting you 10dB closer to an RF overload.

In addition to what Ike explained clearly, any active stage (amplifier) is a potential source of intermodulation effects, which can cause interference.

Mac
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Russell Ault on February 05, 2020, 11:23:42 PM
In addition to what Ike explained clearly, any active stage (amplifier) is a potential source of intermodulation effects, which can cause interference.

...and in addition to that, most amplifiers also produce some non-harmonic distortion (noise) as well, further lowering CNR.

-Russ
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Keith Broughton on February 06, 2020, 06:13:17 AM
Just double checking that they aren't 1/4 wave whips, which need a ground plane.
Just what I was thinking!
If these are the antennas that came with the Sennheiser kit, they are probably 1/4 wave.
Sennheiser does sell a 1/2 wave but it's not a "whip" antenna.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Henry Cohen on February 06, 2020, 09:53:55 AM
...and in addition to that, most amplifiers also produce some non-harmonic distortion (noise) as well, further lowering CNR.

Only if in saturation, or otherwise damaged. As long as the resulting composite amplified RF energy is below the amp's P1, it should still be linear with no discernible distortion, though there will be the inherent noise figure of the component.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Russell Ault on February 06, 2020, 10:34:24 PM
Only if in saturation, or otherwise damaged. As long as the resulting composite amplified RF energy is below the amp's P1, it should still be linear with no discernible distortion, though there will be the inherent noise figure of the component.

I might have this wrong: won't an amplifier in saturation produce harmonic distortion?

The non-harmonic distortion I was thinking of is the inherent noise you mentioned.

-Russ
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 08, 2020, 12:36:37 PM
Sorry to close to hijack this thread. Maybe I should make an own thread..

But regarding noise floor and boosters. Here's a scan of the surroundings I did the other day. As you can see there is "nothing" between the two DTV channels. With this I ask if using a booster is still a such a "bad" thing as if there was a noticeable noise floor present across the current open spectrum. You say it raises the noise floor, but there is "no floor" in this scan. The booster operates at 516-558 so it will raise the DTV, but I don't have any transmitters in those frequencies. They're all between the DTV channels.

Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Henry Cohen on February 08, 2020, 04:31:11 PM
I might have this wrong: won't an amplifier in saturation produce harmonic distortion?

The non-harmonic distortion I was thinking of is the inherent noise you mentioned.

Certainly spurious harmonics are a classic symptom of an amplifier in saturation, but once it is in saturation, an amplifier can can emit all kinds of non-coherent spurious emissions.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Henry Cohen on February 08, 2020, 04:42:55 PM
Sorry to close to hijack this thread. Maybe I should make an own thread..

But regarding noise floor and boosters. Here's a scan of the surroundings I did the other day. As you can see there is "nothing" between the two DTV channels. With this I ask if using a booster is still a such a "bad" thing as if there was a noticeable noise floor present across the current open spectrum. You say it raises the noise floor, but there is "no floor" in this scan. The booster operates at 516-558 so it will raise the DTV, but I don't have any transmitters in those frequencies. They're all between the DTV channels.

There are several issues in play here:

- Since there's no RF level scale in your scan image, we don't know the actual noise floor or the level of the DTV signals.

- The amplifier will raise the level of all RF energy within its passband plus a slope of several MHz below and above (think low Q BPF). so not only will the DTV signal levels be raised, but so will the underlying RF noise floor in the unused channel, which we can't see in this image. That noise floor will rise yet an additional amount due to the composite energy of the strong adjacent DTV carriers.

- The receiver selectivity may not be good enough to filter out the added noise of all the RF energy within the passband, mostly due to the DTV channels.

- The booster amp may be driven into saturation from the strong DTV carriers.

In short, you're far better off running a bigger low loss cable and putting a narrowband channel filter ahead of the receiver. If you insist on using the pre-amp, at the very least use appropriate BPF filtering before the amps.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Jean-Pierre Coetzee on February 09, 2020, 12:08:06 PM
It was also mentioned earlier that what level the receiver is receiving doesn't matter. If you are having dropout issues adding the RF amp wouldn't improve that in any way whatsoever since your SNR is already bad, making it louder doesn't matter. Imagine a channel on your console with a ton of noise and hiss and you can barely hear the instrument through it. Increasing the gain does absolutely nothing to assist the situation.

Henry also mentioned that you may actually oversaturate the amp or even your receiver with the strong out of band signal that is noise. Anything that isn't desired signal is noise if it comes into the input stage of the receiver.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 10, 2020, 09:48:40 AM
Thanks so much. I'm just digging further, theoretically. On the job I sat up there's no RF issues, I just got curious about when not to implement a booster
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Henry Cohen on February 10, 2020, 01:55:32 PM
. . . I just got curious about when not to implement a booster

Only in very rare situations. Essentially, never.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 11, 2020, 10:16:42 AM
Only in very rare situations. Essentially, never.

So, never not implement a booster? :D

Just kidding.

I've used them on 40m stretches of 10dB/100m cables with a barrel extension between 2x20m cables, but I don't get the math to add up, although I was experiencing bad signal/dropouts into the receivers without, but it was good with, and my senn rep told me that I need boosters.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Don Boomer on February 11, 2020, 12:01:58 PM
So if it works, then it works. But there are best practices to follow that would make your system even more reliable. A great number of them are free or very low in cost.

I’m guessing in your case you could switch the cost of a line amp for better coax which will result in at least some improvement in CNR as compared to a booster.  Depending on your local conditions either may work fine but having more stability would be my choice.

I would highly suggest you get a reasonable scanner so you can measure the differences between the two.  Moving forward I believe having a scanner is a requirement for anyone working with wireless mics. The job has just become too difficult to operate reliably without one. 
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 11, 2020, 12:34:49 PM
So if it works, then it works. But there are best practices to follow that would make your system even more reliable. A great number of them are free or very low in cost.

I’m guessing in your case you could switch the cost of a line amp for better coax which will result in at least some improvement in CNR as compared to a booster.  Depending on your local conditions either may work fine but having more stability would be my choice.

I would highly suggest you get a reasonable scanner so you can measure the differences between the two.  Moving forward I believe having a scanner is a requirement for anyone working with wireless mics. The job has just become too difficult to operate reliably without one.

The cables I'm using are equal to LMR400. 
I see a scanner would be handy, but comparing to what jobs we do, it would be merely be recognized as a "gadget". We do maybe four jobs pr year which is 20 up to 28 channels.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Ike Zimbel on February 11, 2020, 02:19:04 PM
So, never not implement a booster? :D

Just kidding.

I've used them on 40m stretches of 10dB/100m cables with a barrel extension between 2x20m cables, but I don't get the math to add up, although I was experiencing bad signal/dropouts into the receivers without, but it was good with, and my senn rep told me that I need boosters.
In this example, you are using the amp to overcome losses in the cable, which is what they are meant for. The math is seldom going to work out exactly, IOW, that the amount of gain in the amplifier is exactly equal to the amount of cable loss. Remember too that there are other areas of loss, like using 2 x 20m cables doubles the number of connectors in the chain, and each connector contributes a small amount of loss. It adds up.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Don Boomer on February 11, 2020, 03:05:24 PM
You say it raises the noise floor, but there is "no floor" in this scan.

There is never zero noise floor.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Jason Glass on February 11, 2020, 03:10:54 PM
There is never zero noise floor.

Truth and wisdom right there, folks.  Whenever you see a theoretical absolute minimum or maximum in ANY measurement, distrust the measurement until you've replicated it with numerous instruments, setups, and operators.  This is true in all disciplines of science and technology.

There are few flat lines in all of nature.  You need to understand that when you see one, it is an approximation either by human design (for various good reasons) or by accident.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Henry Cohen on February 11, 2020, 03:28:08 PM
There are few flat lines in all of nature.

And one of those usually entails a person standing by with defibrillation paddles . . .
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 11, 2020, 03:29:10 PM
Truth and wisdom right there, folks.  Whenever you see a theoretical absolute minimum or maximum in ANY measurement, distrust the measurement until you've replicated it with numerous instruments, setups, and operators.  This is true in all disciplines of science and technology.

There are few flat lines in all of nature.  You need to understand that when you see one, it is an approximation either by human design (for various good reasons) or an accident.

*Sorry quoted the wrong post. Removed.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Ike Zimbel on February 11, 2020, 03:29:20 PM
And one of those usually entails a person standing by with defibrillation paddles . . .
Clear!!!
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Henry Cohen on February 11, 2020, 03:43:03 PM
My tool for the scans are the the antennas connected to the system I use.

This is good practice.

Quote
If they say It's at least a very low noise floor, or "none" where I'll target my frequencies, then that's what i'm getting through that system? I bet there is noise, but why compare noise from a theoretical system A, which I will not use, to noise from system B, which I will use and works at spec, which is the reference for the system I'm setting up? There is noise present, but if it seems good in in a manufacturers view, and I'm using that. And if it works flawlessly, then why bother with "there is never zero noise floor"?

Because, whereas the ultimate goal is to have the maximum and most reliable CNR possible, one needs more than a KUR* (Known to Unknown Ratio) of the environment; one should have quantitative values for the systems used and the environment in which one is operating. Without knowing the actual noise floor, it's impossible to determine CNR and thus stability of the RF system over a longer period of time.
Title: Re: Extending range of Sennheiser EW100 radio mic
Post by: Miguel Dahl on February 12, 2020, 10:19:59 AM
This is good practice.

Because, whereas the ultimate goal is to have the maximum and most reliable CNR possible, one needs more than a KUR* (Known to Unknown Ratio) of the environment; one should have quantitative values for the systems used and the environment in which one is operating. Without knowing the actual noise floor, it's impossible to determine CNR and thus stability of the RF system over a longer period of time.

Righty-O. Thanks again!

I forgot to post a new picture with the actual dBm values for the scan I posted earlier, so here it is, fwiw at this point.