WLIU had been using Musicam USA's CDQ Prima 220s to send programming to our sister station, WCWP, via fractional T1. This setup had been functioning reliably for the past five years with few outages. However, in January of this year the Long Island University's IT department informed us that the T1 was being replaced by an OC48 metropolitan area network link and we would have to replace the Prima's with equipment that would work over Ethernet. The university has had success with a VoIP telephone system, so I started looking at various music over IP codecs on the market. One unit that stood out was the Netstar 500 by Musicam USA. Because we had good results with the Primas, I decided to try the Netstars.
Once they arrived, I set them up in the shop with a back-to-back connection using a crossover cable. The units came preprogrammed with IP addresses for testing. After several minutes of getting used to the menus on the front panel, I was able to connect. I set the compression algorithms to none and used linear PCM with a 44.1kHz sample rate. The audio sounded exactly like the source. Using the menus, it was easy to try out the different compression schemes that were included with the Netstar - MPEG Layer 2 and 3, MPEG 2 AAC, MPEG 4 AAC-LD, G.711 and G.722.
Performance at a glance
|IP or ISDN-capable codec|
Analog or AES-3 inputs
The built-in Web browser made setup a snap. At a glance you can see the status of the current connection and what configuration you have on the near end and also the far end. And you can change the settings on the far end if needed. This can save a lot of time by not having to walk people through the configuration changes if any problems should arise.
The Netstar features analog in/outs along with AES in/out ports. These are selectable from the front panel or the browser. There is a front-panel headphone jack that is selectable for sending or receiving audio, or both simultaneously. The reference level and peak hold times for the VU meters are selectable.
The encoder can be set to match the incoming signal, therefore you can change the near end and the far end will automatically follow when reconnecting.
On the down side, the VU meters do not show up on the Web browser. Although a value can be accessed via telnet, this is only useful for assessing steady tone levels.
The Netstar Web interface provides access to the unit''s functions and settings.
In addition, the Netstar is a full ISDN codec and has a built-in terminal adapter. The U interface is standard but an S interface can be activated by an internal cable change. More than 200 numbers can be stored as user profiles with various settings stored for each number. These can also be used to store IP addresses and settings for Internet connections. These user profiles can then be dialed or connected to with two clicks on the browser. The algorithms available for ISDN are Layer 2, Layer 3, AAC, AAC-LD, G.711 and G.722. Making ISDN calls was as easy as using IP and once the settings matched the Zephyr that we have, the call went through each time.
Besides using the Netstar on the university's network, I tried it on the cable modem that we have. After enabling the DHCP mode and rebooting the modem and the Netstar, I was able to connect to Musicam USA's IP address over the public Internet using MPEG Layer 2 at 128kb/s. Although the audio sounded fine, the connection did not hold any longer than three minutes at a time. Cablevision noted that the signal to the modem was weak and causing packet loss. This was probably causing the disconnects.
Construction of the unit was first rate with a substantial front panel. The keypad is a membrane click type and looks like it will survive for years, unlike the Prima's spongy pushbuttons, which had no tactile feedback. Inside, the Netstar has an Intel D845 micro ATX motherboard with a solid drive memory module installed in the IDE slot. Power is supplied by a standard slim-line PC Power and Cooling supply. The proprietary Musicam cards were horizontally installed on a vertical riser on one of the PCI slots on the motherboard. The motherboard and the riser card had metal bracing to the chassis, which ensures that nothing will work loose over time.
We have been using the Netstar 500 as an STL on the university's network for the last 90 days without any dropouts or connection problems. Because the audio is uncompressed, the quality of the sound on WCWP has improved considerably over the Prima's 128k we had been using. We have also used the return feed to send live music broadcasts from the Tilles Center at the CW Post Campus to WLIU and back again to WCWP with no noticeable audio degredation.
Anderson is chief engineer for Long Island University's WLIU Southampton, NY, and WCWP Brookville, NY.
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