Archive for July, 2011

4G mostly eliminates voice delays in remote broadcasts

July 4, 2011 Leave a comment

Sprint and Verizon are in a pitched battle to sign up people for their fourth generation, or 4G, mobile wireless networks. AT&T seems behind the 8-ball on this, which may be why the next iPhone will still be a 3G phone.

I’ve been using Verizon’s 4G for data for several months. As I’ve written, it’s demonstrably faster than the company’s 3G data network, but it doesn’t work as fast as the 802.11G wireless network in my house that connects to a FIOS fiber connection. I can tell when I upload or download multi-megabit MP3 sound files to and from Federal News Radio using a PC in my house. Sometimes I can’t get more then two bars to show for reception strength, which may be why the 4G feels slightly sluggish in some applications. I haven’t tried Sprint 4G.

Recently I found one application where 4G makes a definitive difference. Comrex Corp. makes a funny-looking gadget that is a stable of radio stations, including my own, Federal News Radio, and our sister station, WTOP. The Comrex is basically a Linux computer with a coding-decoding circuit for transmitting analog voice by digital means. When we do live remote broadcasts, it connects the remote person — often me — with the mixer in the studio operated by the anchor. With the Comrex, you get the good sound that comes with high bandwidth. That is, it sounds as if the remote person is in the studio, as opposed to that over-the-telephone sound.Until this year, we’ve been using the Comrex with a 3G access card. It works, but there’s a noticeable delay, often one second or longer. This has made it difficult to carry on natural-sounding conversations between the field and the anchor in the studio. We’ve designed our remote broadcasts around this limitation. We conduct interviews entirely between the on-location subject and the on-location host (me). The studio anchor is just monitoring until the remote person signs off. It’s how we avoid the listener hearing the awkward pauses or two-at-once talking caused by the delay.

But using a Comrex equipped with 4G, it was possible to have a delay-free conversation with my co-host, Amy Morris, when I was at a remote location in the Washington, D.C. area. Nearly delay-free; there is still a very slight delay. But we overcame it with a couple of moments’ practice.

Now we’re equipping our Comrex units with 4G Verizon cards. Brian Oliger is one of WTOP’s top technical guys. He keeps tons of radio equipment running, from microphones to antennae high up on towers. He told me two kinds of delay occur when using the Comrex. The coding-decoding process can introduce delays of fractions of a second. But network delays can induce delays of up to 6 seconds. With the 4G, Oliger says, the network-induced delays have all but disappeared. WTOP/WFED owns 14 Comrex portables, all of which will be equipped with 4G by the end of the summer. (An additional three rack-mound Comrexes reside within the studios. A couple more exist at the stations’ transmitters, which are remote from the studios.) New Comrex portable models lack PCMCIA card slots, but instead have USB 2.0 ports to accommodate the new way carriers are delivering their networks to computers.

Oliger, an old hand at new technology, is reserving final judgement on the 4G until it becomes popular and there is competition for the bandwidth. Dropped iPhone calls on 3G networks are maddening. But in broadcasting they’re an application-killer.

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