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Smoke in the Modem - IP Audio

By Kirk Harnack [TWiRT] on Nov 1, 2013 4:59:00 PM

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TWiRT 189Chris Crump of Comrex discusses the latest in remote broadcast technology on "This Week in Radio Tech."

Remember POTS line frequency extenders? Then in the 1990’s we did remotes with POTS codecs and ISDN codecs. Now IP is transporting remote audio back to the studio, and for more radio stations, live video is a key part of their digital strategy. Chris Crump with Comrex is bringing us up to date on video remotes and shows off the Comrex Liveshot.



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Announcer: This Week in Radio Tech, Episode 188, is brought to you by the Telos VX multi-studio talk show system. Telos VX is the first and only multi-studio talk show system designed for radio and TV broadcast production. Improved audio quality and cost savings from day one. On the web at Telos-Systems.com/vx.

And now, our feature presentation [two words]. IP Audio is huge in radio, and now wireless IP video is helping radio and TV stations brings back remote TV shots.

[INTRO 00:00:45]

Calm down, he says that to everyone. From his palatial office of important business, or in a choice hotel in a distance land, this is Kirk Harnack. Chris Crump with Comrex joins Chris Tarr [SP] and me with the latest digital strategy for radio. It's video. You're dialed in to This Week In Radio Tech.

Kirk: Hey, welcome. It's time for This Week in Radio Tech. I'm Kirk Harnack, your host. I'm glad you're with us. This is the show where we talk about radio technology, and man, there is a lot of it out there. I just got back from a big [SDE] national meeting, and to see the awards that are given out for engineering excellence, and the keynote speech by Paul Brenner, who's been a guest on this show. There's so much going on out there, and technology is just-there's so much to keep up with.

And this is the show where we at least keep you up on some of it. Introduce you to new ideas and talk about old ideas and make sure that we all understand some of the basic concepts. So, "This Week in Radio Tech" is the show. It's our 189th episode. I'm Kirk Harnack. I work for the folks at Telos. I'm the VP of the Telos division. And also, one of our regular co-hosts is with us, and that's Chris Tarr, calling in today from Milwaukee, Wisconsin. Hey Chris, how are you?

Chris Tarr: Hi there, Kirk. I am the Director of Engineering and Operations for 88.9 radio Milwaukee, which is where I'm at today in our new conference room. I'm working through our semi-annual membership drive downstairs. So, I've been working hard all day. I'm also a contract engineer all over the state of Wisconsin, a contributing writing to Radio Guide Magazine and oh so much more.

Kirk: Yeah, you are so much more. Appreciate that. Also, give a plug for your website, the info website. What is that?

Chris Tarr: It's virtual engineer, and it's at broadcastengineering.info

Kirk: At broadcastengineering.info you'll find forums there, and people who are helpful when you have problems.

Chris Tarr: Exactly. Correct.

Kirk: And if you're a helpful engineer, maybe you could be helpful yourself and answer somebody's problem. Broadcastengineering.info. Our show is brought to you by Axia Audio and the Axia x switch. Does that sound exciting? Maybe not, but it'll solve a problem for you, so, I'll tell you about it later. Hey, and I want to welcome in our guest, Mr. Chris Crump from Comrex. Chris is the sales and marketing director, and he is a wealth of technical information. Chris, welcome in from-you're in the Atlanta area right now?

Chris Crump: I am in lovely Buford, Georgia, with my family and . . .

Kirk: Buford?

Chris Crump: Yeah. Buford, Georgia, with my little puppy Olive, who is sitting on the sidelines, just looking at me.

Kirk: Well, if you get tired or bored, just put Olive on. We'll carry on.

Chris Crump: She can be much more entertaining than I am on many levels.

Kirk: Chris, I think you may have been with Comrex for about as long as I've known you. Tell us-Comrex is a name like Telos, it's just everywhere in the broadcast business. Tell me a little bit about Comrex, and how you all got started, and it's interesting that Telos and Comrex have made competing products for years and yet we've always been pretty good friends in broadcast. I know at NAB shows, sometimes somebody will ask a question, "We need a product that does this," and our answer will be, "Well, we don't have that, but the folks at Comrex sure do."

Chris Crump: And we do the same thing. Like Stereo SDN codex, if you need that, go talk to Telos. Those are the guys that do it. Comrex has been around since 1961, and a lot of people aren't aware of the fact that our very first products were for television. We were making audio products for television. Things like wireless microphones, VHF monitors, IP queuing systems that were [twenty-six based]

Kirk: Oh yeah...

Chris Crump: So a lot of that stuff, our first ten years in the company's existence, when John Cheney, our founder, basically started to put these products out into the market, was revolving around television. And it wasn't until frequency extenders basically popped into our line that we discovered that we could allow radio broadcasters to do much more creative remotes using just a regular analog phone line by shifting around the frequencies down in the 250-Hertz range. So it actually made a remote set a lot more natural over a phone line, for those that couldn't get an equalized line in.

Then we started to develop a line of ISdN codecs in the '80s, followed by a POTS codec in the '90s, and the 2000's got us into the IP queue world. So now we're making IP audio codecs, telephony interface products like telephone hybrids and talk show systems. And to make your point, even though we've been making somewhat competing products, it never seems like they directly compete. We kind of fill a niche, and you guys fill a niche. So I think we kind of complement each other in a lot of ways.

Kirk: Yeah. So, a couple of years ago, we had on the show a friend of yours and a colleague, Tom Hartnett. Unfortunately, I couldn't be here for that show. I was on a plane to Singapore, I think, at the time. But Tom came on, and Chris Tarr, you were here for that show, weren't you?

Chris Tarr: I believe I was. Yes.

Kirk: Crazy thought. Chris, why don't you tell us everything that Tom told us in that show?

Chris Tarr: Right. We've only done 189 of these, so I probably couldn't tell you.

Kirk: I am sorry I missed that show, but, what does Tom Hartnett do for you guys at Comrex?

Chris Tarr: Lead Technologist?

Chris Crump: Tom is our technical director, and basically, he helps develop, or creates the products that I get to sell. He's the guy that sits in his office and swirls the misty mists of the future to determine what technologies are out there that we can take advantage of to make really cool products for broadcasters.

Kirk: I want to run back to something that you mentioned. That was the frequency line extenders. We're going to dip into history for a second here before we move into the present and where the future's going. Because we got some cool future stuff to talk about-well, what you said stations are doing now. I think it's going to be very prevalent. But this frequency extender idea. I got introduced to these, I guess, years ago, although I worked in a little, small market, where we had, of course, dial-up POTS phone lines was how we did baseball games, and car dealer remotes, and church services on the radio, but in this little town of Berea, Kentucky, the local phone provider was GTE. GE? No, GTE.

And, for whatever reason, on a local phone call, they did not high-pass filter the phone call. You had frequency response down to almost DC, which was unusual. Anywhere else in the country, you pick up the phone, you call across town, and you're 300 Hz, about, to 3 kHz. That was kind of unusual, wasn't it, for somebody not to high-pass filter?

Chris Crump: I would say so, but not to be disparaging against Berea, Kentucky, which I think is off of I-75 as you're headed through that state.

Kirk: Yeah

Chris Crump: Might have been one of the technical guys who said, "What's this thing? I don't know, let's unplug it, see what it does."

Chris Tarr: When you only have four lines in the state to connect, it's pretty easy to do.

Chris Crump: And they were all on a party line, too.

Chris Tarr: Right. You were three rings, right? Your phone number was four. I, on the other hand, use Comrex frequency extenders all the time. I worked in smaller markets like you, and I don't know how many Friday night football games were carried over a Comrex frequency extender.

In fact, we had set up, back in the good old days of the 5 Watt bag phone, we had a frequency extender wired into an analog cell phone with a [00:08:11 inaudible] jack and everything else, and it kind of replaced [Marty]. Those frequency extenders were fantastic devices. You really couldn't go to any radio stations that didn't have one of those frequency extenders sitting in their studio. It just opened a whole new world for remotes, because again, a lot of times you're tied to [Marty] systems, with which you couldn't always get a good signal.

Or, it was picking up the telephone and getting that telephone quality sound. The frequency extenders were a fantastic product for their time, because all of the sudden now, if you could find a phone that you could plug this thing into, you were good to go.

Chris Crump: And it's funny because occasionally we get calls from people that have a bag phone and they've got a frequency extender and they say, "Hey, can I get this thing to work?" And it's like, "No, they turned off the amp service that your bag phone uses about ten years ago." So, it's going to be a real trick.

Kirk: One thing that we ought to cover real quick-I'll give the five- sentence explanation of this if I can, then Chris and Chris, you correct me if I'm wrong here. Back when a lot of remotes were done over local phone lines, and a local dial-up telephone line, typically, frequency limited between about 300 Hz, so the bottom end of male voices do not get carried though. It's 300 Hz up to about 3 kHz. And there's signaling that used to go on above 3kHz, and a lot of times, the carbon button microphone in the phone itself would self-limit you to 300 Hz.

If you did that, you always got that nasally, telephony sound. And if you could have gotten through some of the more base frequencies it does make it sound more natural. It makes the brain work less hard when it hears audio. Your brain's trying to fill in what it's used to hearing.

So, Comrex came up with this way to take audio out of a microphone, out of a mixer, and shift it up in frequency by about 250 Hz. Shifted it up, so if you'd listen to this raw audio coming out of this thing, you'd hear it shifted up in frequency. And then, you'd shove it through the phone line at this shifted up frequency, and then at the other end, when you'd receive it from the phone line, you'd shift it back down by 250 Hz. And this had the effect of allowing the base frequencies to get shifted up, pass through the phone line, and then get shifted back down to their original base frequency.

And since our ears-we hear audio frequencies based on octaves and not based on decades. If we can add audio between 300 Hz all the way down to 50 Hz, we've added a couple of octaves, and we've just lost a portion of an octave. We've lost 250 Hz up near 3 kHz of audio as the trade-off. And that' s a great trade- off for comfort and intelligibility. It doesn't give you more high frequencies, in fact, you lose a little bit of high frequencies. But you gain two octaves of low frequencies and it just made it sound better. Now, Chris Crump, did I say that about right, or am I off base?

Chris Crump: I'd like you to repeat that whole thing again...

Kirk: [laughs]

Chris Crump: ... because I was taking notes. No, that's pretty good. I really couldn't add to that. Tom Hartnett could certainly contribute to that conversation, but that's essentially what these things did. Nowadays, some people still use them, but it still kind of sounds like you're talking into a box, in a way. But at the time it was pretty amazing, even though it only took you up to the 3 kHz. The bottom actually made the audio sound so much more natural. On the other end, talking about technology today, on the extreme, you've got what CDMA telephones are doing to the quality of the human voice.

In a presentation I did yesterday at the SBE meetings and the Indiana broadcast association, I ended up talking about how CDMA phones basically rip all the humanity out of the phone, because it's digitized, it goes through a bow-coder, and any semblance of a human voice is all ripped out, so your brain has to work harder to fill in all the holes. With smart phones, you would think that audio would be getting better, but it's actually getting worse. But there are ways that you can make it better, and that's some of the technology that we're working on these days.

Kirk: Yeah. We're going to get into that, with you guys putting Skype into your on-air phone systems so people can talk that way, like we're doing now, except without the video. And maybe there's some more ideas, too. But you're right about this other impairment. When we went to digital cellphones and the cellphone providers went to either proprietary or other very low bit-rate codecs, we've all struggled sometimes to understand somebody on the phone and sometimes we're operating down at four or five or six kilobits per second for a codec to get audio from the phone to the phone company.

It may get turned back into G.711 or maybe G729, but whatever codec that some people have used, or modes that they may operate in when they need low bit rates... Oh my gosh, they can be terrible. And it's this kind of impairment that you can't really just go measure with frequency response, or maybe distortion, because it's not tonal based. There's psycho-acoustic encoding and a lot of math going on.

Chris Crump: Yeah, they do what's called pseudo-noise encoding. The bow cutter is a part of that, and what they're trying to do is they're trying to take eight voice calls and cram it down a single voice channel so they can get more calls on their network.

Kirk: Somebody in the chat room mentioned a two-line frequency extender. Was this something that Comrex did, as well?

Chris Crump: Oh yeah, that was big time. A lot of people used those. We actually came out with a three-line extender as well, which was a little challenging. I think people were happy with the two- line. The three-line got a little bit difficult to get all the lines in sync.

Kirk: So with two lines, you were shifting one audio up 250 Hz, another audio you were probably shifting up about, probably 2500 Hz or so.

Chris Crump: Yeah, so you brought back a little bit more of the higher frequency response.

Kirk: Yeah. So in the end, you'd get about 5 kHz of audio response out of two ordinary dial-up phone lines, yeah?

Chris Crump: That was exactly it. It was a magic 5-kHz box with two phone lines. We sold a lot of those, and we still get those in for repair occasionally.

Kirk: Wow.

Chris Crump: It's funny because-I have to tell you, at Schwartz, for Sirius XM, right after that little announcement from Verizon came about them discontinuing a typical PRI or BRI service on the East Coast, Ed Schwartz sent me a note saying, "Hey, do you have any of those two-line frequency extenders left?" I was like, "Maybe we could go back into production on those. That would be awesome."

Kirk: Is there a reason why those wouldn't work over VOIP circuits? I mean, not connected directly, but if you had an ATA, if you were a POTS connected to an adapter, and then your infrastructure was VOIP. Any reason why that wouldn't work?

Chris Crump: You know something? I really have no idea. This is full disclosure. Those are actually before my time. I never actually used one. I just see them come in from time to time. Honestly, I wouldn't know.

Chris Tarr: Let me tell you why you young whippersnappers...

Chris Crump: Yeah, you guys have to tell me this stuff.

Chris Tarr: It actually should. There's no reason why it wouldn't work. As long as it comes out the other end with that audio pitch shifted, it should work. There's really nothing secret about them.

Kirk: Yeah. Certain things, like fax machines, don't work well over regular VOIP lines, but there is a standard that it can invoke to get that.

Chris Tarr: Well, there's a difference, too, because with a fax machine you're trying to throw bits out. This is actual analog audio that's shifted, so there's no reason why it wouldn't work. On the other hand, if you're doing an ATA to ATA call over VOIP, you already have much better bandwidth than you did over a POTS line anyway, so you'd probably have about the same qualities as if you used an extender.

Kirk: Depending on what codec that the VOIP provider is using. Hopefully, they're using G.711, but a lot of them use G729 or other codecs. Now that bandwidth just keeps getting cheaper and cheaper and cheaper, if you've got a VOIP provider that is giving you some crappy codec because it's lower bit rate, you need to talk to them or change providers. There's really not an excuse to at least use G.711.

Chris Tarr: My provider we have G.711. You can definitely tell when somebody else calls in with that because it sounds phenomenal.

Kirk: Yeah.

Chris Crump: And there's at least [inaudible 00:17:12] providers that are out there. So, plenty to choose from.

Kirk: So, Chris, the next thing I want to ask you about is, for some years, we had this technology of dial-up modem type calls that we ran digital audio through that. Right?

Chris Crump: Yeah.

Kirk: So tell me about...

Chris Crump: ... service.

Kirk: Yeah. But we had a box we'd take out, we took it to a POTS phone line, established a call to a similar box back in the studio, which was also on a POTS line, and then run some fairly low bit rate audio. There'd be a codec there to run your typically mono audio through all of that. Tell me about that era. Is that about the time you joined up with Comrex?

Chris Crump: Yeah, just about. The POTS codec technology came about as a result of computer modem technology being able to digitize audio, send it across as packets, across a circuit switch data network. And it required that you had the ability to pass serialized data across that network, which is why you can't do it on IP or voice over IP. But it was relatively simple technology. Basically, you just dial up a phone number on the POTS codec, which is the receiving end, they establish a connection, and they're capable of doing up to 15 kHz dual mono back and forth over a standard phone line.

Kirk: So what codecs were-Comrex made a number of products like this, and I believe Tieline did, too. Telos really only made one product that worked in any kind of way like this. I think you had the Blue Box and the Vector. What other products did Comrex make?

Chris Crump: The very first product was the Hotline.

Kirk: The Hotline.

Chris Crump: Yeah. That got us kind of on the map. There are people who still use those on a regular basis. So it was a huge product for us. That was early on, and then, as computer modem technology developed, we were able to put in new devices that actually improved the fidelity of the call. Different components have improved it quite a bit as well. After that came the Vector, which was kind of a cool box. Then we did the Matrix, which was a POTS ISDN codec. We did Blue Box after that. So, we had a really good line of successful POTS codecs that really carried us for a couple of decades.

Kirk: It seems that POTS codecs, just like computer modems that you'd have in your laptop or desktop machine, the technology of a computer modem, with the squeaks and the squawks, getting every bit of bits through a connection by frequency and frequency shift keying, and all this, through a given connection-that's what all the squeaks and squawks are, setting up the characters of the phone line.

It seems that this always worked best on what I call real by golly phone lines. Not a university's PBX with a 12-volt battery or something like that. What was your experience and what were your customers' experience in finding out-I know we're talking about ten years or more. Where did a Comrex Matrix work really well, and where would this kind of technology get challenged in terms of the type of phone line you were connecting to?

Chris Crump: Well, there were so many issues a customer's confronted with because not all phone lines are the same. You could have a pair of copper that your phone line is delivered to you on, and the wires could be cracked and it could be lying in a trough full of water and shorting them out. Creating just enough noise on that line so that the lines would equalize and pass the data through sufficiently.

Actually, an equalized line was a great line to be able to use for that. Definitely not a PBX, because that caused some expense in terms of bandwidth that was available for you to transmit. But there are so many-another big issue we had was calling across a lattice between states or providers. That could always cause problems. So many issues that I'm glad that I'm into the IP world, because it kind of brings back a lot of headaches and bad memories of...

Chris Tarr: It's interesting, because as engineers back in the days, I bought one of the first Hotlines that came off the assembly line. You learned as an engineer, you had this checklist of things that you worked on when you're going to do a remote because you knew those things. You also kind of had a bag of tricks. Like, I had an adapter that allowed the Hotline to connect through a PBX system through the headset, so that if you had a data or a true PBX line, it's not analog, so you couldn't actually dial out on it. Or if you plugged it in, the voltage would smoke the modem.

Chris Crump: Yeah.

Chris Tarr: You had those adapters that you could insert in between to get audio. You'd always check the checklist. You'd go in to do a remote and you'd check the internal wiring, you'd check the demark, you'd kind of see how things would work and then usually a pre-remote checklist would involve dialing it up and leaving it connected, or at least knowing how to set the maximum rate, crank it down so that it wouldn't constantly renegotiate.

You tended to learn pretty quickly the ways to efficiently set up those codecs so that they were pretty reliable. And again, that was one of those situations where that opened up a lot of possibilities for a lot of stations. I still-the sports station here with Intercom that I still do some work with, they still use a Matrix. And they still use it for POTS and also for switch data over cellular for that codec. And it works spectacularly, because again, IP's great, and we love IP, and if you can get good IP, it works. On the other hand, still to this day, nothing beats a good, solid POTS connection.

Kirk: Nothing?

Chris Tarr: Nothing. Nothing.

Kirk: For a POTS codec.

Chris Tarr: Correct. You either get ISDN or POTS. You generally don't have the same potential issues that you do with IP. Because again, you order these remotes, what do you get? You've got the remote, the business's house system, which is usually Wi-Fi or a cable modem or DSL, and then you've got to get it back over the public Internet. The IP codecs have gotten much better with that. I call it the law of averages. When you're doing a sports talk show, and you're talking live for 45 minutes out of the hour, the odds of having an IP issue or an IP drop-out are much greater than, for example, if you're a music station and you're just doing some quick talk breaks through an hour.

Kirk: Ah. Yeah. Sure.

Chris Tarr: Often times, with a situation like that, if I can't be certain that the quality of the IP connection's going to be really good, I'll usually default to a POTS codec. Especially on AM, it really doesn't sound back at all.

Kirk: Chris, you sound like you've had some better luck with POTS codecs. It seems like in the late'90s, early 2000's, a lot of POTS connections weren't really POTS. They switched to VOIP somewhere nearby, or they went through some kind of muxing thing, the phone company was out of facilities. They put little boxes around that let them get three or four phone circuits into one pair. They started using a lot of digital technologies, which if you were a voice talker, you couldn't tell the difference. But a modem wouldn't work well over that. Have you not experienced that kind of problem?

Chris Tarr: I'll answer that question quickly, at least for my neighborhood. At least in the Midwest, especially in our area, AT&T hasn't moved a whole lot to fiber yet. So, for example, ISDN lines are easy to get and plentiful, POTS connections are generally true POTS connections. There isn't a lot of fiber conversions. I understand that out East especially, that's a whole different situation, and Chris, you probably get this all the time from your travels all over the country.

Chris Crump: Yeah. And I had a lot of calls from customers, probably about 10 years ago, when they were making a lot of conversions within central offices because the phone companies have told us that they want to get rid of circuit switch data services. They don't want to have to support these huge, mechanical rooms of switches within the central office. They just want to put Cisco routers and switches and hubs in there, and get rid of the five ESS switches and all the circuits switch data equipment. I would take calls from customers that were just livid because their Matrix stopped working all of the sudden and they wanted to know what I did to it. And I'm like, "I didn't do anything to it. Has your phone company made any changes within their central office?" "Yeah." "What did they do?" "Well, they did some VOIP thing."

So, they would basically connect, and it would stutter, stutter, stutter, drop. And that's again, because the POTS codec relies on that serialized data stream to be able to get from end to end, and if any of those packetized pieces of serialized data are interrupted, don't have a connection.

Kirk: Maybe somebody in the chat room knows differently, but it was always my impression that the phone company has been G.711 inside the phone company for a long, long time. So if you go from an analog phone line, into a proper G.711 converter, and now it's carried as very simple G.711 in the US U-law coding, and then you come out the other end, from G.711, wherever it gets switched, and then to a POTS line and then back into a POTS codec-that works. That's not a problem. G.711 is very accurate and not problematic for modem type signals.

It's when they went to other codecs, especially psycho-acoustic codecs. G.711 is not psycho-acoustic. It's just math. It's just fast math, low delay, and low frequency bandwidth, but it matched what analog circuits were designed for. But when they started going to other codecs to get lower than 64 kilobits for the bit rate... Remember 15 years ago when everybody had to have a fax line as well as their usual lines? The phone companies in some places had to increase their capacity for 30, 40, 50 percent because of all the fax lines that were being bought back then.

Anyway, my point is that there were technologies that, to my understanding, screwed up your modem type connections. Remember the days you took a laptop to a hotel and it just wouldn't connect very well? That's the kind of thing I'm talking about. Either crappy PBX or psycho-acoustic encoding, which is fine for voice, but not fine for when you've got to transmit, frequency shift key with lots of carriers. It doesn't work so well for that. I'll get off this subject. Anything else to add about what I said?

Chris Tarr: I think the phone companies have actually been pretty good about the copper to VOIP transition, because there are still a lot of fax machines out there and they all work. So, obviously there's a pretty good chance that if you're hooking up to a POTS line, that a voice codec like that will work. That's number one. And number two, I know that, as an engineer, I always have to be specific nowadays with businesses that are going to use one of these devices.

And I have to say specifically, "Do you have a fax line?" Because a lot of times, they say, "Oh, yeah, we've got a phone line." And you go in and it's a VOIP line, and you go, "Well, that's not going to work. I need a fax line." Like I said, knock on Formica here, I really haven't had any issues. Every time I've ordered a POTS line, unless it's wired improperly or something like that, I've always been able to get a Hotline or a Matrix or what have you. I've always been able to get it to work on POTS, and in fact, a lot of times it works better than anything else.

Kirk: You live there in the Midwest, where people are nice and the engineering is good.

Chris Tarr: And the POTS flow free.

Chris Crump: And I have to tell you, one of my favorite Comrex tech notes-when I first joined the company-basically told you how to make friends with your local Telco guy. So that's just another little trick in your tool bag where you basically give them a pair of concert tickets, a tee shirt, some station mugs. It's amazing how many people have had to rely on that kind of bribery to get their remotes on the air.

Chris Tarr: Oh yeah. I agree completely.

Kirk: And we thought that was just in third world countries. But no, bribery works here, too.

Chris Crump: Even in Milwaukee. Right, Chris?

Chris Tarr: That's right. Well, you know, bribery is the international language.

Kirk: Hey, you're watching This Week in Radio Tech or listening to it. I'm Kirk Harnack, your host, along with Chris Tarr from Milwaukee, Wisconsin, and Chris Crump, director of sales and marketing for Comrex. Makers of fine codecs. IP and POTS codecs, and phone systems and something really cool we're going to talk about in just a few minutes.

Our show's being brought to you by my employer and my friends at Axia Audio, makers of something kind of new. Actually, it's just been shipping now for three or four months. It's the Axia x switch. Axia brought out live wire, live audio over IP. Very low latency, very high quality. They brought that out, gee, it's been almost fourteen years ago. Steve Church gave a talk about this in 2002. I think we started shipping some products in 2003 and 2004. So, it's been out there for a while.

One of the things that some engineers have had some trouble with, is getting switches, typically those are high quality switches from Cisco or HP, and getting them configured right. Inside a Cisco switch, there are a ton of command line configurations that can be done, and some of them do need to be done to work with extremely low latency, live wire IP audio packets.

Well, Axia decided, "Hey, let's make our own switch. Let's make our own switch that's pre-configured, that's guaranteed to work." Now, it works with all other kinds of traffic, too. It's fully compliant with any kind of traffic that you want to throw at it over an IP network. But it also comes ready to work with live wire IP audio. Also, in fact, it uses the same chipsets that are found the really expensive iron. Chipsets from Marvell, for example. Another thing that the x switch does is it gives you some ports that are PoE. Power over Ethernet. And that's pretty cool, too.

So, the x switch is very easy to set up, there's virtually no configuration. I think there's a couple options if you really dial into it. It's powered by AC, of course. It's just a half rack wide. Let's see, you know I should have been a little better prepared. Let's take a closer look at the back side of one of these. It's got two of those SFP ports-small-form factor pluggable.

So, will it connect to fiber? Absolutely. Just buy a fiber adapter for it and this is a real standard, off the shelf thing, and it's got two ports for that. It has I believe two gigabit ports on it, and it's got eight 100 megabit ports on it. 100 megabit ports are what usually connect to all kinds of peripheral devices around your studio. Any kind of live wire stuff from Telos, or Omni, or Axia, or from other companies that have a live wire port on their gear. And four of those ports provide you with power over Ethernet, PoE.

So, if you've got VOIP phones, like these that are behind me for your phone system, you can plug them right into that. The power will come right from the switch. It'll power the phone, plus give you the full Ethernet capability right there. The x switch, easily deployable in studios, if you just need, "Oh, you know what, I've got to put a switch here," you don't want to buy a Cisco switch that's maybe kind of big or takes a lot of time to configure. You just don't want to mess with that? Get an x switch from the folks at Axia.

By the way, it's the same physical form factor as also the Axia x node. So, if you need a couple things on a rack, like an x node to provide you with analog or AES audio in and out of your live wire network, pair it up with an x node right next to it. And that x node will, of course, run the x switch, and can run other things as well. I'm sorry, the x switch will run the x node. And other things as well.

Something else to consider-the Axia's x nodes-this is the audio interface that's available for, you know, old-fashioned stuff that uses analog or AES-these can be powered with AC power or with PoE, power over Ethernet. The power budget for an x node is about 15 Watts. And so you can power it with PoE-power over Ethernet. You can get that PoE from the x node in the same rack, or in one RU, or elsewhere in the room. The point is, you can dual power your x node with AC power and PoE from, say, one of our x switches.

So, if you want to check it out on the web, got to Axiaaudio.com/xswitch. Make that like one word. The letter x and the word switch. And you can read all about the x switch there. It's really cool, our guys in R&D have just done a fantastic job of designing this thing and setting it up and making it super easy to use. All right. Thanks a lot for Axia Audio being our sponsor in "This Week in Radio Tech." Oh, by the way, it's got this really cool OLED display on the front, and you can see at a glance the status of all of the ports, including the gig ports and the SFP ports, and whether they're providing power or not to devices they're hooked to. Check it out, Axiaaudio.com/xswitch.

All right, you're watching episode number 189 of This Week in Radio Tech. I'm Kirk Harnack, along with Chris Tarr, and our guest, Chris Crump from Comrex. Chris, we've been talking about the past here, I guess it's time to shove right here into the past and the future.

Chris Crump: And thank you very much for doing the future because I have left so much of that behind me. My brain is so full of everything I'm doing now.

Chris Tarr: It's like we're causing you flashbacks.

Chris Crump: I'm like, "Oh my God, I don't remember any of this."

Kirk: Chris, earlier this afternoon, we were talking about your recent experiences. Walking into radio stations and being a little surprised at the non-radio things that you see. Tell us about what trend you're noticing.

Chris Crump: I travel all over the world, and I'm into radio and television stations all the time, and it's been really surprising, the number of radio stations that have either a full video editing suite, or studios that are just filled with cameras and lights because they're basically contributing to a television morning show, or they're broadcasting their shows on cable. I'm seeing it with a lot of sports talk stations in major markets. Look at what Kidd Kraddick does with his Dish Nation, and all of the stuff that they're doing video wise.

So, radio has really started to make a leap away from just being an audio source. They're become content creators, and they're basically contributing content for cable channels, cable networks, and even just local television shows. And the web, of course. That's a big part of it as well.

Kirk: Alright, so, I've tuned around to some European radio stations on the web and seen them producing video, and Chris Tobin, who's one of our regular co-hosts on this show-not here this week but usually he is-often mentions that the CBS radio stations in New York actually produced a lot more video every day than the CBS television stations. It typically wasn't broadcast over the air, it was streamed on their website, but if you wanted to watch a talk show being made, there it was. Chris, I take it you're seeing a lot more of this outside the US? What are you seeing in the US as far as video?

Chris Crump: In the US, you talk about CBS, it seems like all of the groups in major markets that are consolidated, they all have a digital media director in that market who's responsible for the video content for the website, or streaming, or however they want to present. But it's really a big part of what CBS is doing. I was in ClearChannel San Francisco a couple of weeks ago and was really amazed, because they have a full-blown editing suite that rivals a lot of TV stations that I see. So, stations are investing in video because, what is TV other than radio with pictures? Don't tell that to a TV guy.

Kirk: Chris Tarr, at either of your facilities-you used to take care of Intercom, or where you are now, at Milwaukee's 88.9-what are you seeing?

Chris Tarr: Same thing. Same thing. With Intercom, I'm still involved with them and they have a director that does essentially nothing but video all day. And they go out and they shoot. When we built the facility here, we had video in mind when we planned it, and we have a professional guy who does a lot of our video.

I think everybody's doing it now. It's just a matter of, you know, starting small and ramping that up. I think the price points have come down, and the quality of the tools have gone up enough, to where, in the hands of a skilled producer, it's not all that difficult for radio stations to produce video content. I think what Chris is seeing is pretty common across the country. I think we're seeing more and more of that.

Again, we have the on-air component, which is great. It's our audio, it's what's on the radio, it's what's on the website, but we have to come up with ways to bring people back to our websites to do things. Websites typically have been static, not changing very much, kind of entities, where you go and visit it once and you don't go back. Same thing with Facebook and other types of social media. It's great that we're posting status updates about what the jocks are doing and things like that, but that's not really compelling.

On the other hand, when you can create video content that includes their favorite radio presenters, and some of the things that go on behind the scenes, and even some of the in-studio concerts and things, that's compelling video. That brings people back to their websites and engages them in social media. So, it's almost something you have to do at some point or you're going to miss the boat.

Kirk: Interesting. Interesting. At my small stations, I was thinking that we don't do video, but yeah, we do. In American Samoa, we actually have a very manual-we have some lipstick style cameras around the studio, and we hire a guy to come in and push buttons and switch cameras. And then when songs are playing, I think we're running video billboards, "Happy Birthday, fo-lo-lo," you know, that kind of thing in American Samoa. I feel like I'm a bit out of touch with some of the bigger markets and what they may doing in terms of video.

But one thing I have noticed, I don't want to spill all the beans here,-we're going to get another tour later on-but Gary Klein was on here ten episodes ago or so back, and he gave us a tour of the new Nash facility in Nashville, of the new Blair Garner studio there, and it's fully outfitted with HD cameras. They're not streaming anything yet, but they will be sometime early next year, along with social media stuff and weather forecasts, and just all kinds of fancy-schmancy stuff.

So, yeah, it's really going to be video. But I didn't mean to run off on that tangent. We're here to talk about Chris, and Chris, what you and Comrex are doing, what you have to offer to video content and producing that content. Tell us where Comrex comes into that.

Chris Crump: Well, obviously we have a lot of experience with pushing IP over data networks; whether it's the public Internet, 3G wireless, 4G wireless, and just regular IP type networks. At NAB several years ago, we just got bombarded with people that came up and they looked at the Axis audio codec, which is kind of our flagship product, and they said, "We love the form factor of this. It would be great if it did video." "Well, we don't do video, we're an audio company." And then we had conversations about it internally, and we figured that we could probably do a video codec and kind of go back to our early roots of television.

So, we spent a lot of time and resources and engineering effort to develop the Comrex LiveShot, which is our video over IP codec, which is essentially does for video what our Axis does for audio. And I just happen to have one right here. Look at this.

Kirk: What? That's tiny.

Chris Crump: It is. It's very tiny. So, it's not a lot bigger than our Axis audio codec, and it's designed to fit onto the back of a standard Anton Bauer mount for a professional video camera. The Anton Bauer battery just chunks on to the outside of it like that, and then you take the output of the camera, whether it's - let's see if I can get this out-okay, there we go. Whether it's HD SDI, SDI, composite, or HDMI. There's an SDI loop for feeding a monitor, or some kind of recording device.

The interesting thing about this is it's a full duplex audio and video codec. So, not only can I send high quality audio and video back to the studio over IP, but it can also take a return as well. Kirk, you could be doing a weather forecast out in the field, and you get green screen back. As long as your green screen doesn't blow away in the tornado behind you.


Kirk: Yeah. So it's fully two way, then? One has to ask, there are other live multi-modem solutions out there, but I hear some of them just have incredible delay. I think you guys have a much shorter delay than some of your competitors do.

Chris Crump: Optimally, we shoot for like 200 ms of in -ode delay and that's pretty average. Regardless of the bandwidth that you're using. The propagation delay might be an additional second or two at the most. Our whole goal is, with your full duplex interaction of your broadcast, you're able to actually talk to the-Ow, I just hit myself. You're able to talk with your host, your anchor back in the studio, from the field and have a comfortable conversation back and forth. That's kind of the whole purpose of this product. Low latency, high quality audio and video, with an audio queue channel as well. So, you could have a completely discrete IFB, or audio queue channel offline so your cameraman can get directions from the director back in the studio, in addition to having program audio and video return.

Kirk: Yeah. The form factor you're showing there-now, that's a form factor that a lot of radio engineers, including myself, were not very familiar with until you explained it to me. You said, "That's the standard mount on the back of a camera," for I think you said, an Anton Bauer battery. There's a couple different mount styles, aren't there?

Chris Crump: Yeah, the other one that's pretty popular is the Sony B mount, which you would find on a Sony camera. That's pretty popular in Europe, but in the United States this seems to be the dominant mount. On the West Coast you have a lot of folks who use the Sony B mount, but we have adapter plates for that. The two basic industry standard mounts in the television industry, or the video industry, are the Anton Bauer mount and the Sony B mount.

Kirk: [country accent] Now, what are those two goose-neck microphones there on the top?

Chris Crump: [country accent] Well, if you want to talk, you just talk into it like this.

Kirk: What are we looking at?

Chris Crump: This is a little Comrex innovation. You asked what Tom Hartnett does. This is what Tom Hartnett does. He comes up with these cool innovations. This is actually a USB mast. What this does is it keeps the devices separated from each other so there's no RF interference, and also gets it away from the cameraman's head, so he doesn't get a [Schwarzenegger voice] tumor in his brain. We kind of like to keep these up and out of the way of the cameramen so you get a little bit better reception on these devices. So you can plug in...

Kirk: As engineers, we believe that that would be helpful. Do you find empirically, that getting the antennas up and out of the way and apart from each other is, indeed, helpful to the signal [mounts]?

Chris Crump: We do find that it really helps. In some cases, we might have to add-; because these things radiate maybe a Watt, or sometimes a little bit more, so we can put an RF choke on this to improve the signal as well. There are a lot of little tweaks that we have been making on this device over time. It's been a really nice device, and right now, we've got several stations in the country around the US that are using it, but it's really popular in Italy right now. They're loving it over there. They're actually using it on KA band satellite, and they're doing live broadcasts from all over the country of Italy over satellite.

Kirk: You showed it with some modems there. Can it also hold a Wi-Fi USB stick?

Chris Crump: Yeah, this is our dual band Wi-Fi that comes with it.

Kirk: Oh.

Chris Crump: The great thing is, I could have a Verizon and an AT&T. I could have a Sprint, I could have Wi-Fi 3G, Wi-Fi 4G. Basically, the technology we've developed-it's called CrossLock technology- creates a secure VPN tunnel between this portable unit in the field and a rack mount unit in the studio. It basically [muxes] all these channels, it bonds these devices together so you can take advantage of cumulative upload speeds and download speeds in both of these devices. It does a very intelligent, sophisticated analysis of what's happening on the network. So, if it senses that the bandwidth is being throttled, it can load balance to the other device. It can actually do some variable bit rate encoding on this as well, so that it can reduce the amount of bit rate required if the bandwidth on the network reduces.

Chris Tarr: Yeah. Yeah.

Chris Crump: And it does that dynamically. You might lose a little bit of fidelity in the image quality, but it will ramp back up as it improves.

Kirk: I was going to ask, I think I asked you that, but I want to make sure I understand; at first, you said you can aggregate the speed of these two devices. Maybe it's two different 4G on two different carriers, maybe one's Wi-Fi going to a good hotspot and the other one's going to a carrier- whatever it may be-but you've got two streams available here and you can aggregate those and get a higher overall throughput and then a bigger bit rate for your video and audio, but I take it that if one of them is getting impaired pretty badly, you're going to want to throttle the bit rate down. How do you decide whether you want to use it for more bit rate or for just redundancy that you may be needing because you're in a bad spot? Is there, like, an automatic algorithm that decides that?

Chris Crump: There is, and the engineers won't tell me how they do it. They say, "Oh it's secret sauce. It's too complicated for you to understand. It's magic."

Kirk: The box at the studio, what does that look like?

Chris Crump: I don't have one here right now, but you can see it on our website. It's just a 19" rack mount device. It has a little navigation button and an LCD panel on the front, and then it has analog AES audio in and out, it also has that audio queue channel in and out. Then it has a couple of B and C connectors for HD SDI in and out, composite in and out, and then there's an HDMI output for monitoring. Relatively simple box, but it's essentially this box in a different form factor and slightly a different package.

Kirk: You call this a LiveShot and, obviously, you put this on the back of a camera and you do a live shot back to the studio. Is there any reason why you couldn't-let's say your wanted to do a remote production with two or three cameras. Could you switch them and use that LiveShot as kind of a fixed base, and shoot that back to the studio?

Chris Crump: Yeah. That's kind of what the CrossLock technology-Well, first of all, you could actually have multiples of these associated with a rack device back in the studio. And you could switch between them. But yes, you could actually have a rack mount in the truck and a rack mount in the studio and just transmit over IP, take your output off your switcher into that device and send your audio and video over IP back to the studio.

Kirk: Wow. What do radio engineers think when they begin to get presented with this notion of, "Hey, you're going to have to do video now, too." I haven't had to do that much yet. And I know a little bit about video anyway, but what do you find in the field? How do engineers take to this?

Chris Crump: I find that they can be hyper-critical of video quality. So, their tolerance is a lot less than professional video engineers.

Kirk: Really?

Chris Crump: Yeah. Because I think they take it very seriously and they want to make sure that it's done really, really well. Because they are radio engineers. That's been the case with some of the folks that I've talked to. But some people really embrace it. A lot of times, if you look at a group like Journal, for example, where they've got co-located radio and television, there's a natural synergy there, and they can kind of lean on television to make that work. Capitol Broadcasting would be another example. There's some synergy between radio and TV, so they kind of lean on their video engineers. All of us who are radio people first and foremost, we're going through a really intense education learning about video. It's not an overwhelming challenge, but it's certainly a lot of stuff you've got to learn to basically make all this stuff work

Kirk: Chris Tarr? You still with us?

Chris Tarr: [snoring] Huh? No, Chris is absolutely right. There's a learning curve for us, and I do think that a lot of times we're more critical of the video than TV engineers, just as probably TV engineers are more critical of audio than we are. It's one of those things where we think that we need to be, because this is something that we're not as tuned to as TV engineers are. However, I do see things like these coming into play in radio.

You know, wouldn't it be great if-I know, for example, the top 40 station here, an Intercom station, does a Kissmas bash every year, which is a big event. Wouldn't it be great if you could do that live on the web? Professionally. I know with us, sometimes with 88.9, we do concerts outside of the building. Wouldn't that be great? To be able to do those from a remote location.

Right now, I find a lot of times, radio stations with their video, it's all locally produced or it's acquired and recorded off-site and then put online afterward after it's been produced. We're just now getting those capabilities of doing a live broadcast and also having live video accompany that. I think that's going to be in the future for sure. And I think that if you're a radio engineer and you're not looking at these things, and you're not thinking about those things, you're going to be in trouble because it's going to get to the point where you're going to be forced to, and you should probably start brushing up on it now while you can.

I am excited, I saw little glimpses of that Comrex product in some of the trade magazines. It's really interesting to see that in person. And it also leads me again to my half joke where I walk around and say, "Oh, Internet. Is there nothing you can't do?" Because it really has-; I mean, if you think about 10 years ago, some of the things that we're talking about right now. Imagine trying to do those 10 years ago. Just the costs involved in doing those things.

All of a sudden, the Internet has come around to be this great equalizer, and we have these innovative companies, like Telos, and Comrex, and Tieline, all looking at IP technology and creating these-they're not cheap, but they're lower cost ways to do all of these things that we could never imagine before. It reminds me that it's a great time to be doing this. It's a lot of fun.

Chris Crump: One thing that I will say, in terms of video for television; this is focused primarily on doing a remote broadcast, getting audio and video from a remote site back to a studio or even from a remote location wirelessly back to a truck, and then microwave or satellite back to the studio. I've been really amazed as I've traveled around the county at how many radio stations own technology like a Newtek Tricaster, which is basically a little TV channel on a box. So, basically it's production, editing, and streaming all in one. Or a rush work system. There are scads of others. So, I think people are making an investment in this technology so that they can provide that content and, like Chris said earlier, not be left behind.

Kirk: So, Chris, I'm curious, and people in the chat room are asking a bit, with your audio codecs, you guys have done some development of your own codec, and you've used some industry standard codecs. What kind of video codec is being used for this transmission? From the LiveShot.

Chris Crump: We're using H.264. That's a pretty standard, ubiquitous coding. It's basically MPEG-4 for video. H.264 is the standard. We are doing something a little bit different. A lot of people just use, like, the main profile of H.264. I have a chart around here somewhere, but there's like seven different profiles within the H.264 encoding algorithm, and you could leverage those to get better image quality, lower latency, lower bit rate or a higher bit rate, depending on what you want. So, there's a whole slew of those that you can choose from. We use all of those based on what profile you've selected.

Kirk: Ah, got you. Got you. Chris Crump has been our guest on This Week in Radio Tech. We've spent half the show talking about how to get video, and how to get video from a remote site back to your radio or TV station. That's pretty interesting. I think we're going to see a lot more video, as Chris Crump has seen himself, at various stations. And Chris Tarr has been involved in this too. Going to see more and more video at radio stations. It's something that we're going to have to learn about.

First it was IT, like in the period of this show's operation, IT has come along, IP has come along big time. And now video, we're going to need to be adding that too. Chris Crump, thank you for being with us. Anything you'd like to add about where to contact you and how to find out more about the LiveShot or other Comrex stuff?

Chris Crump: I will say one thing. One thing I've noticed with radio stations doing video-a lot of times they don't get the lighting right and that's really a huge part in making sure you have good video. So, there are so many things you have to consider when you're looking at doing video. But, if you want to look at what we've got for doing remote broadcast for video, you can go to comrex.com, C-O-M-R-E-X dot com. Feel free to give us a call. In Devens, Massachusetts, 800-237-1776.

Kirk: Alright. Chris Crump, thanks for being with us. And Chris Tarr, I understand you've got to go, buddy, but thank you for being along with us and taking the time to get on the special time of This Week in Radio Tech.

Chris Tarr: Glad to be here. I got to get back to trying to raise some money for Radio Milwaukee. One thing you just mentioned that I wanted to reinforce is that video is now radio tech. It really is. It kind of encompasses all of those things now. It's interesting, you know, how we've progressed. Being a broadcast engineer in radio means, not only the transmitter, but IP and video and all these other things. So, pat ourselves on the back for being so gosh-darn talented.

Kirk: We're going to have to do some how-to shows about video. About what HD SDI means, and what is HDMI? And do we still use composite here and there? What to buy when your GM says, "We're going to do some video of the morning show on the website." What do you got to do? You got to stick a webcam up and get on Ustream or something more sophisticated? It's going to be interesting. Alright. Chris Tarr, thanks for being with us. Chris Crump, thank you for being with us also from Buford, Georgia. Appreciate you.

Chris Crump: Thank you, Kirk.

Kirk: Alright. Our shows' been brought to you by Axia Audio and the Axia x switch, the newest member of the Axia family. It's a little Ethernet switch that has really a lot of power in it and handles live wire streams just perfectly, plus anything else you want to throw at it in the IP world. Check it out on the web at axiaaudio.com/xswitch.

Thanks to Andrew [Zarian] for producing today's show, and you can always check us out on our website at thisweekinradiotech.com. You can watch, listen, or download, or subscribe to our episodes. You can do the same things at the GFQ website, gfqnetwork.com. And check out of the other shows available on the GFQ network as well. There are some pretty good ones out there, and you're going to have a good time watching them. We'll see you next week, folks, on This Week in Radio Tech. Bye-bye everybody.

Announcer: That's all the bandwidth we can pilfer this week. Another torte has propagated. All the transmitters and audio equipment live happily ever after, thanks to the handsome engineer and his kind, benevolent care. We'll be back next week. This Week In Radio Tech. Subscribe to iTunes and you'll never miss a show. Search for This Week In Radio Tech in the iTunes store. Soliciting is strictly encouraged.

If you like today's show, tell a friend. If you didn't like it, we were never here. Kirk Harnack's wardrobe provided by the Salvation Army and the Red Cross Disaster Relief Services. Hair and makeup provided by Penny Lope Garcia Hernandez Weinberg. This ends this transmission. Tango, Whiskey, India, Romeo, Tango, signing off.

Topics: IP Audio Network Routing & Control


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