Field Report: Tieline Technology Patriot

The Patriot from Tieline Technology delivers bi-directional 15kHz mono audio over a standard phone line using its special codec and a custom-made modem to provide solid performance. The Patriot will communicate with other models within the Tieline family, including the Commander with ISDN and the I-Mix ISDN and POTS codec.

I can describe the Patriot in two words: stable and dependable. This product left an indelible first impression in our shop. Here is a device that addresses many of those woes and headaches we've all experienced in field production and broadcasting.

Tieline's proprietary coding algorithm provides the most stable performance I've ever witnessed in a POTS codec. It achieves compression factors on the order of 20 times or more. This allows remarkable communication at a rate of 28kb/s, comparable to Layer II and Layer III that need rates of at least 64kb/s to 128kb/s to be effective. It even delivers fairly good audio quality down to rates as low as 9.6kb/s.

Performance at a glance
Stable performance
Superior audio quality
Remote control of audio from either end
Loop back and tone generator aid setup
Toolbox software support package
9,600 baud data stream concurrent with audio
Low delay
Negotiates data rates up and down

The unit is the lowest-priced Tieline codec product, but certainly not at the bottom on quality and features. The retail price per unit makes it affordable even for a penny-conscience operation. Some stations are using these units as cost-effective backups for their studio-to-transmitter links.

Out of the box

In the middle of the Patriot is a large rotary-encoder knob for navigating through the menu-driven setup. A 10-button soft-touch keypad, including user-assignable function keys, allows quick access to various features and dialing functions.

A useful feature on the Patriot is the ability to remotely control volume levels from either end. Even if the remote engineer gets distracted and levels get out of hand, the studio engineer can control input levels to the remote unit via front panel controls or with the Toolbox software package. In the event that field and studio engineers become distracted, the intelligent gain control (IGC) sets levels based on program material over a five-second duration.

A built-in 400Hz tone generator and loop-back feature assist in testing and troubleshooting connections between the studio and the remote site. Once a link is established, the Patriot negotiates for optimum performance, changing data rates up and down until a stable link is established. Line quality (LQ) can be monitored on the LCD display. Line quality of 35 percent or better is acceptable while levels below 20 percent prompt the unit to renegotiate the rate for a more dependable connection. A new rate can be renegotiated in about 1.5 seconds.

Dialing up the studio has never been easier. The Patriot has a 50-number memory and can redial the last number used. In the event that the connection is interrupted, the codec can be programmed to auto reconnect.

The codec sports a number of convenient interfaces, including solid XLR audio connectors for switchable mic and line levels as well as RCA jacks. A 3.5mm cell phone jack provides an interface for standard cell phone audio. Four audio controls are located on top of the case, two for input audio and two for monitoring outbound send and return audio from the studio.

A 200b/s serial port provides data communication to a laptop computer for remote control, chat or setup using the Toolbox software. The software is included with the purchase of the Patriot. One CMOS relay contact is available on the nine-pin female connector for a user-defined remote control function. Soon to be released will be a secondary nine-pin male connector for 9,600 baud data communications.

It uses Windows

The Toolbox software application aids configuration, remote control and monitoring of the Patriot. If Toolbox is running on computers at both ends, a chat window facilitates communications between the studio and remote operator. Even faster communication rates are possible over the secondary data channel using terminal emulation software. Data is transferred using a standard computer or laptop and a serial RS-232 connection. Toolbox helps keep the phone book up to date as well as upload the most current system software.

An additional tool within Toolbox is the Line Quality Monitor. Samples of LQ are taken every 30 seconds and displayed on a graph in one-hour blocks. Scroll through the history to observe LQ over a period of time for advanced phone line troubleshooting.

The ultimate test

Our test package had no more arrived when it was on the road to a remote. One of our regular engineers called in sick at the last minute and everyone else was booked. I had just a few hours to pack, drive through rush hour traffic and set up for an afternoon sports talk show in a neighboring town. It was the worst combination of circumstances possible.

“Where are your phone lines?” I queried while dropping 50 pounds of equipment on the floor. With 30 minutes to air were patching cords at a fevered pace. I thought to myself, “This was not the best time to try something new.” Finally, the proprietor of the restaurant showed me the phone line. It was a POTS line but routed through a PBX. Could things get any worse? Earlier in the day I had set up the studio unit temporarily on one of our PBX POTS lines just for sake of testing with no intention of actually going on the air.

Five minutes to air and I'm dialing up the Patriot. The unit negotiated and locked at 24kb/s even through two PBXs. Sound checks came through loud and clear. Even at 24kb/s the sound was amazing with just a hint of digital artifact that was noticeable to a well-trained ear, but imperceptible over the air. I thought that digital delay was inevitable at such a connection rate. As published, the delay was insignificant (about 100ms) and the remote talent interacted smoothly with callers live over the air. My line quality remained around 34 percent with no dropouts.

Tieline Technology

Later, I took the time to examine the Patriot under less hostile conditions on the bench at the station. The audio was superb down to even the lowest of connection rates, considering that this was carried over POTS. Playing my favorite classical CD, I was impressed with how smooth the response was in music mode. As data rates dropped, high end disappeared and digital artifacts became more pronounced, yet the audio was still acceptable and air-worthy.

For improved low data-rate/narrow-band response, Tieline developed a special voice mode algorithm to minimize digital effects. While the Patriot was intelligible down to a rate of 9.6kb/s the sound was a bit grating. This lowest rate is probably practical for short news clips over worst-case phone lines. Total harmonic distortion was around 0.4 percent from 800Hz to 12kHz at a 33.6kb/s connection rate. Voice mode figures varied from 2 percent at 800Hz to 7 percent at 5kHz at a 28.8kb/s rate. Despite what the numbers reflect, to the instrument that counts the most (my ears), the sound was pleasing.

The Tieline Patriot fits the bill for bare-bones, dependable and cost-effective POTS codec transmission. Sales, promotion and accounting alike are singing the praises of this little box. Oh, and let's not forget, engineering is rather partial to it as well.

Chestnut is assistant chief engineer at Entercom, Kansas City.

Editor's note: Field Reports are an exclusive Radio magazine feature for radio broadcasters. Each report is prepared by well-qualified staff at a radio station, production facility or consulting company.

These reports are performed by the industry, for the industry. Manufacturer support is limited to providing loan equipment and to aiding the author if requested.

It is the responsibility of Radio magazine to publish the results of any device tested, positive or negative. No report should be considered an endorsement or disapproval by Radio magazine.

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