by Scott Helmke

In 2021, we featured a round of special webinar presentations from industry veteran and RF expert James Stoffo. Both sessions are available to view on our YouTube channel.

This blog post is the sixth entry in an ongoing series all about wireless systems – background info, best practices, and useful tips & tricks. Click here to get caught up on the previous articles.

This is the sixth blog article in our wireless series.  In the previous article I wrote about using frequency coordination software to help decide what frequency bands to use when buying wireless gear.  In this article I’ll be writing about deploying antennas, and why you need “antenna distribution” instead of the usual tangle of individual antennas on your rack.

Antenna Deployment Guidelines

Assuming you’ve just got one channel of wireless (i.e. one transmitter and one receiver), you probably have two receiver antennas.  The reason is because things don’t tend to work all the time with just one antenna. Wireless signals tend to be a bit finicky, which makes sense when you understand that they’re moving at nearly light speed and constantly bouncing off anything made of metal. What can happen (in fact, often does happen) is that two or even more reflections of the same signal will arrive at the antenna, but at slightly different times.  Because of the time difference what the antenna picks up might be a massively degraded signal, and what you end up hearing is the audio dropping out for a moment.  The solution for this is “antenna diversity”, which is a fancy way of saying “two antennas”.  Simply put, the odds of weird stuff happening at one antenna are pretty high, but much lower with two antennas.  So you get two antennas, the receiver has two places to plug in antennas, and the most important thing to do is locate the antennas away from each other.  Most receivers that have the antennas attached only give you a few inches of separation, but a couple feet is much better.  Also it can help to put the antennas at different heights, with different angles, etc.  Remember that word “diversity”.

Beyond just having antenna diversity, it’s important to place the antennas where they can “see” the wireless microphone.  Wireless works best on “line of sight”, where there is open space between the transmitter and the receiver antennas.  If the receiver is mounted in a metal rack away from where the microphone will be used, then the antennas need to be mounted somewhere out in the open, not buried inside the rack where the metal walls will block any RF signals (yes, I’ve found installations where this had been done).  Antenna mounting kits and extension cables are available for this purpose.

Antenna Distribution

What if you have more than one microphone and receiver?  What if you have a dozen microphones and receivers?  Having all those antennas tangled together around the receivers is not only inconvenient and looks silly, but it can also cause reception problems.  That’s because as the RF signal is moving all over the place and bouncing off everything made of metal, they’re bouncing off the antennas as well.  Having two antennas close together means that neither one will work as well, and a whole bunch of antennas is even worse.  The solution is antenna distribution systems.

Antenna distribution is actually pretty simple. It’s exactly the same concept as running a splitter off your cable TV service to connect more than one television.  You’d have one antenna connected to a splitter, which has several outputs to feed several receivers.  In the wireless microphone world everything is doubled because of antenna diversity, but it’s the same concept.  Everything looks cleaner, and because you only need one pair of antennas you can buy better antennas and share the benefit over all your receivers. And manufacturers make it easy by selling antenna distribution units matched to their products – often the antenna distributor will include power outputs so you can get away from using all those wall wart power supplies for the receivers.

Conclusion

What if you absolutely can’t afford antenna distribution?  Maybe you’re even using wireless so cheap that the antennas are permanently attached to the receivers?  Well, you can still use some of the above guidelines to improve your reception.  First thing is to make sure your receivers have a clear view of the action!  Put the receivers up where there is line of sight to the microphones.  And spread the receivers out so that the antennas have some space.  Don’t just stack everything in a pile, spread them out as much as possible.

Now that we’ve established some guidelines for antenna deployment, your next question might be: “What kind of antennas should I actually use?”. While your first thought might be to use the “whip” antennas that come bundled in with the purchase of a wireless system, there are many other options available that can greatly improve the performance of your wireless systems. Please join me in our next blog article “Fancy-pants antennas and why should you even care?”.

Interested in purchasing a wireless system? Reach out to our Sales Team at 847-367-9588 or sales@tcfurlong.com for comprehensive help selecting the right wireless system for your needs, complete with antennas and all the other accessories you’ll need.

We also carry hundreds of channels of production wireless equipment in our rental inventory, and our experienced Project Managers can help design and implement a wireless system for your next show. Reach out to them today at 847-367-9588 or rentals@tcfurlong.com to get started.

by Scott Helmke

In the months of May and June 2021, we featured special webinar presentations from industry veteran and RF expert James Stoffo. The first webinar, Antenna Theory for Wireless Systems, was held on May 25th 2021, and a full recording is now available on our YouTube channel. Our second webinar featuring a presentation from James, Strategies for Large Scale Wireless System Deployment, is available as well.

This blog post is the fifth entry in an ongoing series all about wireless systems – background info, best practices, and useful tips & tricks. Click here to get caught up on the previous articles.

This is the fifth blog article in our wireless series.  In the previous article I wrote about standalone frequency coordination software, and I recommended you actually download Shure’s Wireless Workbench (WWB) and spend some time learning it.  At our office we use WWB quite a bit, and sometimes long before we’ve even got wireless systems to coordinate.

This article is about actually choosing what wireless gear to buy or perhaps rent.   On the surface it seems simple, you have $X and you need quantity (Y) microphones, right?  Well it starts that way.  You figure out you can buy four (4) microphones, you call up a dealer (timely reminder that TC Furlong Inc. is an authorized reseller for all major manufacturers of production wireless equipment, and that we carry hundreds of channels of wireless mic, IEM, and intercom systems in our rental inventory), and the second question they might ask is “which frequency band do you want?”.  Right about there is where the plan starts going off the rails.  You have to choose a frequency band?  How do you do that?  You just want some microphones!  While we are always more than happy to make recommendations on the best frequency band for your purchase or rental, understanding the subject will help you quite a lot too.

What are Frequency Bands?

The story with “frequency bands” is that a wireless microphone system can only tune to a limited range of frequencies.  The cheapest stuff is built with one frequency – that’s it.  If there’s a TV station on that frequency, you’re out of luck.  The most expensive wireless has a wide tuning range, such as Shure’s Axient Digital which can tune over the whole legal UHF TV band.  Your budget will likely fall somewhere between the two, meaning that the manufacturer might have two or three different frequency bands to cover the UHF TV band for the wireless series you are buying.  There might also be a couple bands available in a different part of the spectrum, such as Shure ULXD in VHF.  

So what you need to be able to do is figure out what frequency band would work best for you, in your specific location.  This is where frequency coordination software is invaluable.  Not only will it help you avoid buying into a frequency band that has very little space available for microphones, but it can also help you avoid buying gear that will interfere with wireless you might already own.  We do this a lot in our sales and rental offices, using WWB to play “what if” games based on a customer’s location and existing wireless gear.

How to Choose a Frequency Band

Without getting into trying to teach everybody how to use WWB (Shure has some great videos available on the subject), the process is just to start up WWB, put in the local postal code, and enter in all the wireless gear that might already be onsite.  It’s even possible to put in the specific frequencies that are being used.  After saving that as a “show” file in WWB so that it’s easy to start over, just put in the microphones or other wireless systems you are thinking of buying.  Maybe put in extra channels, just to see how many frequencies WWB can find for that specific make, model, and frequency band.  It’s pretty easy to see whether there’s space available or whether you need to try a different frequency band. Below is an example of WWB displaying available bands of Shure QLXD wireless. The vertical red bars represent TV stations to avoid.

There are some strategies to consider while doing this, beyond just finding what might fit.  If you already have a Shure wireless microphone receiver that can connect to WWB, you can usually use it as a “scanner” in WWB to see what’s actually in your local spectrum (though only for the frequency band of that receiver).  You may also be able to rent a compatible receiver or scanner that will cover the whole spectrum that you’re interested in.  

Also, it’s good practice to put microphones and in ear monitor (IEM) or intercom systems into different frequency bands when possible.  Keeping the powerful IEM transmitters out of your microphones’ frequency band will help reduce interference and intermod problems.

Conclusion

A final consideration for choosing specific gear is just the practical.  Buy the best you can afford, and if somebody generously offers to buy a bunch of cheap wireless be prepared to politely explain how those systems wouldn’t work in your situation.  Good wireless isn’t cheap, but the good news is that even the less expensive systems from reputable manufacturers are still pretty good quality.  Please don’t buy “too good to be true” systems from eBay; often these are cheap clones of the real thing and might not even be legal to use.

So, is that all there is to it? Actually, we’ve now covered the most important steps to having a successful wireless deployment.  But there’s more – in our next blog article I’ll be writing about antennas, how to use them, and the importance of proper antenna distribution systems.

Need help with a frequency coordination for your next show? Frequency coordination is just one of the many services we offer.

Interested in purchasing a wireless system? Reach out to our Sales Team at 847-367-9588 or sales@tcfurlong.com for comprehensive help selecting the right system – in the right frequency band – for your needs.

We also carry hundreds of channels of production wireless equipment in our rental inventory, and our experienced Project Managers can help design and implement a wireless system for your next show. Reach out to them today at 847-367-9588 or rentals@tcfurlong.com to get started.

by Scott Helmke

This blog post is the fourth entry in an ongoing series all about wireless systems – background info, best practices, and useful tips & tricks. Click here to get caught up on the previous articles.

This is the fourth blog article in our wireless series. In the previous article I wrote about actually finding (or more often, predicting) good frequencies for wireless microphones and other wireless audio devices using simple built-in features. This article will be about using standalone frequency coordination software.

There’s a saying that goes something like “Marconi invented interference when he built his second transmitter”. We can’t really confirm that, but there’s a lot of truth to the saying. And I would imagine that like every other successful inventor he had to come up with a solution, possibly one that Tesla had already found, but that’s a different topic altogether.

What Do Frequency Coordination Softwares Do?

Wireless systems manufacturers have been providing some type of system for dealing with multiple channels for many years now. While it’s straightforward to calculate intermod frequencies and generate lists of safe frequencies, it’s only been in recent years that the average audio tech has had access to enough computing power to actually do it themselves for large systems. And today we have several choices in standalone software to help coordinate large groups of wireless systems.

These software applications do roughly the same thing. You enter your location (usually just a postal code), and you enter information about the wireless systems you want to use. For instance, you might have six channels of Shure ULXD in the G50 band, along with four channels of Sennheiser Evolution IEM in the A band. The software uses your location to figure out which TV channels to avoid, based on FCC databases of TV broadcasters. The software then calculates frequencies for all the gear that you have entered. There may also be remote control of attached wireless gear, including the ability to use attached receivers to scan the local RF spectrum instead of relying on downloaded information.

Which Frequency Coordination Software Should I Use?

The first really modern software application dedicated to coordinating large event wireless is Intermod Analysis System (IAS) from Professional Wireless. This software downloads FCC data on TV stations and includes a large database of wireless products from different manufacturers. It’s not cheap, being about $550 for the professional version. But for years it was the only solution available for coordinating large wireless systems, and it has been a mainstay in the professional event world.

The main competition to IAS is Shure’s Wireless Workbench (WWB). This software started as a tool for coordinating and controlling only Shure wireless products, originally the UHF product line which had an early system for networking receivers together. As Shure has developed more and more products with modern networking they’ve continued to update the software, and within the past few years Shure added other manufacturers’ products to the coordination database. With the most recent versions of WWB it is possible to coordinate large events spread over multiple stages, even if you are not using Shure gear. Below is a recording of a webinar we hosted with Shure in 2020, where we discussed the features of the latest WWB update, and analyzed a coordination done in WWB for a large multi-stage music festival:

Other manufacturers do have software for coordination, but limited to compatibility with their own products and with limited coordination tools. Sennheiser’s Wireless Systems Manager (WSM) does allow users to create profiles for non-Sennheiser gear, whereas Shure already has many profiles included in WWB.

Which software should you use? Shure’s WWB is an easy choice, since it is completely free to download and use. Professional Wireless’s IAS is more of a professional tool, allowing you to trade certain risks in return for more frequencies. If you have a large amount of Shure systems which can be controlled by WWB, then being able to deploy your coordination to the equipment with just a few mouse clicks is a huge time saver compared to manually tuning everything. If you have a large Sennheiser system then you might find it worthwhile to use WSM even with its limited coordination features.

Conclusion

The uncomfortable truth about coordinating large wireless systems is that a lot of people are doing it, and a lot of those people are not professional wireless technicians. Quite often it’s the school theatre teacher who has been “gifted” with a motley assemblage of different wireless systems from different manufacturers, and who has to figure out how to make them all work together. For almost anybody who works in live audio and might be using wireless microphones, I strongly recommend downloading Shure’s WWB and watching a few videos to learn to use it. It’s not especially difficult to learn, and can make a huge difference in the success of your events.

Stay tuned for the next article in the series. Next up, we’ll give you some guidance to help you choose the right wireless gear for your next rental or purchase.

Need help with a frequency coordination for your next show? Frequency coordination is just one of the many services we offer.

Interested in purchasing a wireless system? Reach out to our Sales Team at 847-367-9588 or sales@tcfurlong.com for comprehensive help selecting the right system – in the right frequency band – for your needs.

We also carry hundreds of channels of production wireless equipment in our rental inventory, and our experienced Project Managers can help design and implement a wireless system for your next show. Reach out to them today at 847-367-9588 or rentals@tcfurlong.com to get started.

by Scott Helmke

This blog post is the third entry in an ongoing series all about wireless systems – background info, best practices, and useful tips & tricks. Click here to get caught up on the previous articles.

This is the third blog article in our wireless series.  In the first article I talked about how wireless microphones fit into unused space in the TV broadcast spectrum, and in the second article I talked about other frequency bands outside of the UHF spectrum.  This article is about actually finding (or more often, predicting) good frequencies for wireless microphones and other wireless audio devices.

What is Intermodulation?

Now that we know roughly what space we have available for our wireless channels, we can talk about actually deciding what frequencies to use.  If it’s just one channel, we can usually just pick a random frequency in between TV stations.  But if we’re using two or more channels then we have to work around a rather inconvenient problem with wireless audio devices – frequency intermodulation or, more commonly, “intermod”.

Intermod is the result of what happens when two (or more) transmitters or other devices are placed close together.  Because the circuitry inside isn’t especially linear, and because a full RF shield around the circuitry would be cost and size prohibitive, the signals that are being transmitted by one device will leak into the circuitry of the other device. This results in extra frequencies being generated, based on the design of the transmitter circuitry and other things. If you hold two transmitters together in your hand, a frequency scan will show those two frequencies along with others that have been generated by intermod. In the image below, the small “spikes” are frequencies generated by intermod. And those extra intermod frequencies will cause interference just as much as any “real” frequency transmission.  This adds a huge amount of complexity to finding frequencies to assign to our wireless channels.

The good news is that intermod is predictable.  Based on the characteristics of the circuits inside wireless systems, we can calculate the likely intermod frequencies and avoid using them. This becomes a huge amount of math to do, so specialized software is used to do the calculations.

Finding Good Frequencies & Avoiding Intermod

The simplest way to find good frequencies is to use the groups and channels that are loaded into wireless systems.  These are calculated by the manufacturer and take intermod into account – each group will have a number of channels which can be used together safely, assuming you don’t try to use more than one group.  This is often supplemented by a webpage provided by the manufacturer that will recommend specific groups and channels based on your location.  For example, Shure has their Wireless Frequency Finder page which allows you to enter your location (just the Zip code is enough) and which product series you are using.

Another approach to finding frequencies is to use the built-in scanning function found in most wireless receivers. The usual process is to turn off all your transmitters, run the scan on the first receiver, and use the first frequency it finds.  The associated transmitter would be turned on and programmed to that frequency, and then the process is repeated on the second receiver.  This approach has the advantage of avoiding any local interference, but the downside is that it is tedious to perform on a large system.

Conclusion

The frequency finding methods I’ve talked about so far are good if your wireless microphones are all the same – same manufacturer, same model, and the same frequency band.  Typically you can get away with using the above methods if you have more than one frequency band, as long as the bands do not overlap.  But if you have gear from more than one manufacturer, and/or different product lines, you can’t use the built-in groups and channels safely.  And the scanning functions may not make good predictions for avoiding intermod.

The answer is to use software which can coordinate frequencies for large systems, such as Shure’s Wireless Workbench or Sennheiser’s Wireless System Manager.  In our next article, we’ll take a look at frequency coordination software, and discuss how it can aid in larger scale wireless system deployments.

Interested in purchasing a wireless system? Reach out to our Sales Team at 847-367-9588 or sales@tcfurlong.com for comprehensive help selecting the right system – in the right frequency band – for your needs.

We also carry hundreds of channels of production wireless equipment in our rental inventory, and our experienced Project Managers can help design and implement a wireless system for your next show. Reach out to them today at 847-367-9588 or rentals@tcfurlong.com to get started.

by Scott Helmke

This blog post is the second entry in an ongoing series all about wireless systems – background info, best practices, and useful tips & tricks. Click here to check out the previous article and get caught up.

In the previous blog post I wrote about using production wireless systems in the unused gaps between TV stations in the UHF band, and how we’ve lost a lot of the spectrum that we used to take for granted.  The obvious next question is “is there any other spectrum available for production wireless?”

The answer is generally yes, although there isn’t a lot of spectrum lying around empty and available for us to use. 

VHF

The two VHF frequency bands (88-108MHz and 174-216MHz) are available aside from avoiding TV stations.  However, using those lower frequencies usually means larger antennas are needed.  Also, there are some other sources of interference which could cause problems.  RF noise radiating from unshielded network cabling (and almost all Cat5/Cat6 cabling is unshielded) is much more of an issue in the VHF band than in UHF.  I have also seen LED stage lighting to cause a lot of noise in the VHF band, even in cases where UHF microphones were not affected. Interestingly, it also appears that modern digital TV works better in UHF than VHF, and so nobody is in a hurry to start a new DTV station in the VHF spectrum.  

As far as VHF products go, Shure manufactures a VHF version of their ULXD microphone systems, including VHF antennas.  Radio Active Designs makes the UV-1G wireless stage intercom system which uses a proprietary AM technology to fit a large number of frequencies into the VHF band.  And if you’ve still got some old VHF relic that still works, it’ll probably still function just as well as it ever did.  TC Furlong Inc. has ULXD in both UHF and VHF bands available for rentals, as well as a RAD UV-1G wireless intercom system.

2.4GHz

A popular frequency band for inexpensive microphone systems is the 2.4GHz WiFi band. A large number of products are available for this band, usually marketed for amateur uses.  This frequency band is often usable for one or two channels of wireless audio, but rarely more than that simply because of the limited amount of space available and because it is shared with many other devices.  This can be a risky place to put wireless microphones, because you usually don’t see much interference until the audience shows up and starts using the WiFi on their phones.  On the plus side, wireless microphone systems in this band tend to be very easy to set up and use, since frequencies are chosen automatically and will adjust or ‘frequency-hop’ to avoid interference if possible.

900MHz

There are some specific frequency bands in the 900MHz range available for production wireless.  902-928MHz is available, though it can suffer from the same problems as the WiFi band.  Microphone systems in this band tend to be inexpensive, and carry the same concerns as 2.4GHz systems.

Another band is 944-952MHz, which is actually *not* available unless you have a specific license and are able to coordinate with other licensed users in that band.  944-952MHz is the “Studio Transmitter Link” (STL) band, which as the name suggests is allocated for broadcasters to connect studio locations to broadcasting towers. While many such studio links are now being done over the Internet, this band is still tightly regulated.  Manufacturers of wireless microphones in this band tend to be picky about who they will sell to because of the licensing concerns. Shure sells their PSM1000 systems in the X1 band, for instance, but recommends that potential users use Shure’s Wireless Workbench software and suitable hardware to scan for unused frequencies.  My own advice on using the 944-952MHz band is that you should work with a regional RF coordinator to make sure that you aren’t causing any problems for the primary users of this (or any) frequency band. For a deeper dive and more resources, head to the National Spectrum Management Association website.

The DECT Band

The DECT band (short for ‘digital enhanced cordless telecommunications’), 1920GHz-1930GHZ in the USA, is used for things like cordless phones.  It’s also used by some wireless intercom systems such as Clear-Com’s FreeSpeak II. This band has the same limitations as the 2.4GHz WiFi band, though the ‘frequency-hopping’ technologies in higher end products like FreeSpeak II allow for reliable performance in all but the most adverse conditions. FreeSpeak II in the 1.9GHz DECT band is available in our rental inventory.

Conclusion

To sum up, UHF is still the best spectrum for high quality wireless microphone and IEM use.  It’s the spectrum with the best RF characteristics for wireless audio, but also where you’ll find the highest quality products.  Other bands are available but limited in various ways.  If you need to have more channels of audio than you can fit into UHF in your locale, then consider prioritizing critical channels for UHF and moving other channels (such as backstage intercom) to other bands.

Stay tuned for the next article in the series. Next week’s topic: finding good frequencies. What is intermodulation and how can you avoid it? What is the basic process for setting up a simple system with a few channels of wireless? Check back in for the answers.

Interested in purchasing a wireless system? Reach out to our Sales Team at 847-367-9588 or sales@tcfurlong.com for comprehensive help selecting the right system – in the right frequency band – for your needs.

We also carry hundreds of channels of production wireless equipment in our rental inventory, and our experienced Project Managers can help design and implement a wireless system for your next show. Reach out to them today at 847-367-9588 or rentals@tcfurlong.com to get started.