OT: Where wireless mics are headed

Coursedesign wrote on 7/8/2007, 11:13 AM
This is the end of traditional narrow RF channels and worry about whitespace (abandoned analog TV channels taken over by others after the switch to digital TV, etc.), interference, and more. I don't see how the other manufacturers aren't already working on this also (possibly using a certain different non-UWB technology with similar advantages):

Audio-Technica announces 6GHz SpectraPulse wireless

At the recent InfoComm show in Anaheim, Audio-Technica introduced SpectraPulse, a pulse-based ultra-wideband (UWB) wireless microphone system.

A completely new application of UWB technology, SpectraPulse operates in the 6GHz range, bypassing congested RF environments to deliver clear, intelligible audio without the performance and setup issues associated with conventional wireless systems. Using wireless boundary mics, the system uses up to 14 simultaneous channels without RF competition, frequency hunting/coordination, white space issues or infringement from other wireless systems or radio sources. Audio response is optimized for voice intelligibility.

[...] The SpectraPulse system represents one of the first commercial sound implementations of UWB technology, which has recently been licensed for indoor commercial use by the FCC. The technology allows the wireless transmission of data in short-duration pulses over a wide spectrum of frequencies. Operationally, a series of nanosecond pulses, occupying an instantaneous bandwidth of 500MHz within the 6GHz frequency spectrum, arrives at a single receiver in precisely timed sequences. The SpectraPulse system incorporates the technology to decode these pulses, making the system inherently secure and preventing signal interception by other wireless systems.

For a higher level of security, Audio-Technica will offer an optional encryption package that meets the AES 128-bit encryption standard developed by the U.S. government.

SpectraPulse components include: the mtu101 microphone transmitter unit; drm141 digital receiver module; aci707 audio control interface; and cei007 charger encryption interface. The mtu101 microphone transmitter unit features a programmable touch-sensitive switch and nine-hour rechargeable battery life. The digital receiver module consists of an integrated UWB antenna and 14 channels of digital wireless transceiving, with power and data carried over a Cat 5 connection. The aci707 audio control interface is in a 1RU package for the demultiplexing and audio output of up to seven channels. Seven distinct line/mic level audio outputs are provided on standard Phoenix-type connectors. A separate charger/encryption unit charges up to seven mtu101s and allows for encrypting of the mtu101 units using optional encryption software.

Manufacturer: www.audio-technica.com.

(From http://broadcastengineering.com/audio/audio-technia-spectra-pulse-infocomm/)

Comments

rs170a wrote on 7/8/2007, 12:42 PM
The folks on the rec.audio.pro newsgroup don't think too much of the technology so far :-(

Mike
farss wrote on 7/8/2007, 1:01 PM
The local AT agent seemed a bit uncertain about it too as it's most likely strictly line of sight. The good news was that hopefully our existing 800MHz spectrum will get shifted down to 600MHz, still using FM modulation.

Bob.
Coursedesign wrote on 7/8/2007, 1:58 PM
Lots of speculation, much of it based on ignorance.

A given chunk of spectrum can hold the same number

The above statement is true in theory (specifically because of Shannon's Theorem), but I don't believe it is anywhere near true with practical equipment.

UWB is not line of sight. If it was, you couldn't use it to penetrate thick cement walls (a major current use in Search & Rescue operations).

UWB is not the same type of limited bandwidth spread spectrum as in say cordless phones that typically hop between 40 channels over a few tens of MHz. UWB hops across a spectrum of several GHz, which makes a big difference.

Thanks to the high data rates, I don't believe latency will be an issue either. And we know from its use in covert communications that it's *incredibly* difficult to interfere enough with it to impact reliable transmission.

Still, I'm expecting to get a few more years of life out of my AT (high end) VHF wireless mic system that I have been using for nearly 10 years all over Los Angeles, including in difficult environments where I would have bet against it working (and I had large spools of XLR cables for backup). Amazingly, I never had a problem with interference (I guess a bit of luck helps :O).

There are actually multiple technologies for avoiding current and future channel problems. UWB is just one of them, and it will be interesting to see how it works in real life products.

If my life depended on reliable sound for film today, I would get Zaxcom's digital wireless systems with recording and on-demand playback built into their body packs. With these, if there is an interference problem, you just press a button and get an error-free signal retransmitted afterwards, with full time code of course.

Steve Mann wrote on 7/8/2007, 6:43 PM
Your analog wireless gear is safe for the foreseeable future, maybe many years. First, the DT switchover has to be final before the spectrum can be auctioned off and there's already requests from some small stations for a reprieve. (Most unlicensed UHF wireless mics operate in the whitespace between the low UHF TV channels).

Next the FCC has to hold their auctions which can take a long time. The last round of spectrum auctions took over two years. Then there will be the usual sour-grapes lawsuits from the losers further delaying the new use of the spectrum by years more.
TheHappyFriar wrote on 7/9/2007, 5:49 AM
question: in 10-15 years won't these mic's use frequency's that get cluttered just like everything else? I mean once everyone starts switching to these frequencies/methods then it won't be as "clean"? Like TV, cordless phones, CB radios, walki-talkies, etc.

Sounds cool. Honestly, I'd hope the FCC DOESN'T auction off a large part of the spectrum & keeps it for general communications/broadcast, etc. So we can have devices that work on UHF from the store, like communication systems, etc. UHF seems to have a decent range with relatively little power consumption (using a Nintendo wireless wavebird as an example here: it's on UHF & with two AA batteries has a range of a hundred+ feet. Even though walls & other things. And no lag time. The blue-tooth & FM gadgets I have can't compare. I even have an ATI UHF remote that worked hundred+ feet away no problem.
Steve Mann wrote on 7/9/2007, 5:05 PM
"Honestly, I'd hope the FCC DOESN'T auction off a large part of the spectrum & keeps it for general communications/broadcast, etc."

Auctioning the spectrum to the highest bidder has been the plan for fifteen years.

When we go digital (as in UWB) we can theoretically put thousands of radios in the same UWB band. You won't ever experience interference as with analog gear, but there's a very real risk of digital delays of a few milliseconds when the spectrum gets crowded. (We're talking Olympics or Super Bowl crowded).
TheHappyFriar wrote on 7/9/2007, 5:10 PM
I know they plan on it, I just wish they'd open it up for development instead of selling it off is all. I've been saying that for ~10 years now. :)
DJPadre wrote on 7/9/2007, 6:58 PM
for 7 years, my G1 Senny has ben going strong (knock on wood) for 4 years almsot, my G2 has been following along quite nicely.. i cant fault them and the only issue i had was shooting my the water with many active boats obviously messing with the UHF signal..

I cant complain, as one dropout in 6 years of use is pretty good odds... If it aint broke, dont fix it
Coursedesign wrote on 7/9/2007, 9:56 PM
There's Wideband and there's Ultra Wideband...

With UWB, there is not what we normally think of as a "band" as in say "the SW band" (3-30 MHz) or "the FM band" (88-108 MHz).

The signal spans a huge frequency range, say 3-10 GHz, which is sometimes described as "line of sight," but this should not be taken literally, in an "everyday" sense. This specific radio communications term merely means that, unlike LW/MW/SW signals, the signal will not go over the horizon.

Extensive experience has shown that the multi-GHz frequencies actually propagate quite nicely in modern cities, as demonstrated for example in the 1.8 and 1.9 GHz mobile phone bands.

Of course we can expect to get some interference from Wi-Fi, microwave ovens, and more, but the strength of UWB implementations lies in their ability to avoid problems with even a larger number of crowded frequency bands within the total Ultra Wide band used by UWB.

I think a lot of people wish that they wouldn't fiddle with the current frequency allocations, and many even think the whole Digital TV thing is just a nuisance, because the analog TV picture quality they are seeing every day is "just as nice as it ever was."

Still, if asked, everybody wants progress.

It's the change they can't stand.

vicmilt wrote on 7/11/2007, 4:20 AM
"Everybody wants progress. It's the change they can't stand."

Oh - I love that!!

Is it yours, or is it a quote from someone else?

I'm gonna use that line somewhere, for sure.

Thanks,

v
Logan5 wrote on 7/11/2007, 9:30 AM
My wireless system the Harpoon 204 on camera receiver - if it detects ANY interference, it will fire a tazer gun like cable into the on-camera talent – then using the cable to carry the RF signal back.

I smile every time I use my system.

www.WireLessLine.com/harpoon

baysidebas wrote on 7/12/2007, 1:47 PM
Well, here's the Roller of wireless mics: http://zaxcom.com/press_april_10_2007.htmZaxcom[/link]
Coursedesign wrote on 7/12/2007, 1:52 PM
"Everybody wants progress. It's the change they can't stand."

Frankly, I don't remember. I've been making that observation for two decades, but I suspect I'm not the first.
farss wrote on 7/13/2007, 6:26 AM
Everything Zaxcom makes has serious drool value although I do prefer the Aaton field recorder. The Cantar X is a masterpiece of engineering, not just waterproof, the dang thing is gas tight. If you ever get near one, pull a knob out to see how they do it.

I was a bit taken aback to learn that the local agent has sold at least 7 of these units this year. That was until I stumbled onto a 35mm shoot by a local film school and the audio trolley had two of them on it.

Bob.
Coursedesign wrote on 7/13/2007, 8:54 AM
The Cantar X is magnificent indeed, a work of art.

But if there is any kind of transmission problem from the wireless mike(s), then it has no input.

Zaxcom's most advanced (and tiny) wireless body pack can also record what it picks up, simultaneously with trying to transmit it to the receiver. If the audio fails during a money shot, it takes seconds to remotely ask the mike to retransmit what was lost, and with time code to boot...

It doesn't get any cooler than that! :O)
farss wrote on 7/13/2007, 2:44 PM
What really caught my eye in the Zaxcom range is that their transmitters are actually transceivers. So a back channel can be used for foldback or so a boom op can hear the director.

I'm seeing the people on the vision side of the business getting more interested in the audio side as well lately so some Zaxcom gear could be on the horizon. What I'm really liking about their RF link is it comes much closer to Wire Less than anything else I've seen.

Bob.
Coursedesign wrote on 7/13/2007, 4:12 PM
The other thing about Zaxcom's Wire Less system is that it sounds like Wired.

Their fully digital system (not hybrid) really sounds close to an XLR cable...
baysidebas wrote on 7/13/2007, 5:21 PM
"I'm seeing the people on the vision side of the business getting more interested in the audio side as well"

And it's about time they do. I learned early in my video career the mot viewers will tolerate sub-par video, but anything less than perfect audio will send them running.