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The New Mobile Broadcast via AoIP
The evolution of the Telos Zephyr has produced the Z/IP One, a single rack-unit, full-duplex codec. This device has two mic/line level balanced inputs and two balanced (analog) outputs. For communications, it has two integral Ethernet connections; one can be used for streaming, while the other is used for control purposes with its built-in Web browser (it can also be configured via its front panel.) The codec supports Livewire. Additionally the unit is supplied with a Wi-Fi stick, and you can plug a 3G modem in to its USB port. A feature that Telos calls ACT (agile connection technology) senses network conditions and dynamically adapts the codec performance to provide the best audio. There is an 8-bit parallel GPIO port for signaling and control, along with an RS-232 channel. The Z/IP One has a large set of codecs available: AAC-ELD, AAC-HE, AAC-LD, MPEG Layer 2, MPEG 4 AAC LC, MPEG 2 AAC LC, G.711, G.722 and linear PCM. On the far end, you would have another Z/IP One.
Worldcast (APT) has a line of IP codecs, and the one we'll look at is the Horizon NextGen. This is a single rack-unit, full-duplex codec, two channels in and out, available via line-level balanced or AES-3. (Another Worldcast codec would be on the far end.) It has two integral Ethernet ports; one can be used for streaming, and the other for control (using the Worldcast GUI or a browser). Alternatively, there is an option called SureStream, which allows the user to set-up two simultaneous independent IP streams that can be configured go out on a per-port basis, or together on the same port (either one). Both Ethernet ports can be configured for static IP or set for DHCP. Included algorithms are Enhanced apt-X (16 and 24-bit) and linear PCM (16, 20, 24-bit). Optionally, MPEG 4 AAC HEv1/2, MPEG AAC LC, MPEG 4 AAC LD are also available. GPIO consists of four optically isolated inputs, and four relay outputs. An RS-232 path is also available for the transmission of ancillary data. There aren't any front panel controls, so you will need to have a device that can run a browser along with you when you use this device.
Musicam offers the Suprima, a 1RU full-duplex codec. (Another compatible Musicam codec would be on the far end.) This device supports two channels of audio, with line-level balanced inputs and outputs (along with AES versions of each on a db9 connector). It has an integral Ethernet connector used for streaming as well as control (via embedded Web server). Coding algorithms supported are MUSICAM MPEG1/2 Layer II/III, MPEG2/4 AAC LC, MPEG4 AAC LD, MPEG4 AAC-HE, Standard & Enhanced apt-X, G.722, G.711, and uncompressed PCM. GPIO provisioning allows for up to seven contact closures; serial data is supported when using either apt-X or MPEG algorithms. Like the Musicam Road Warrior I mentioned earlier, this codec can communicate via ISDN, as well as X.21 or even V.35; so it might be a good choice if you want to segue into IP from ISDN, instead of going cold turkey.
I keep hearing stories about how some phone companies, in various parts of the country, are no longer accepting ISDN orders. Here in New York, Verizon still does, but the writing is on the wall. No matter where you are, and no matter what your local phone company supports today, tomorrow could easily see a big change.
Irwin is transmission systems supervisor for Clear Channel NYC and chief engineer of WKTU, New York. Contact him at firstname.lastname@example.org.
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