A Marriage of Art and Science

Designing a successful baseband modem is quite a challenge. It must be able to operate at a variety of data rates, over a variety of distances, and be able to use several different guages of wire. Furthermore, in each application, a successufl baseband modem must support error-free communication at the greatest distance possible. The design engineers at Patton Electronics Company have met this challenge with the Patton Model 1090 KiloModem PS (TM).

The Patton Model 1090 supports point-to-point synchronous communication over two twisted pair wires in guages rangin from 19 to 26 AWG (.7mm to 4mm.) Supported distances range from 4.9 km at 160kbps using 26 AWG (.4mm) all the way upt to 17.8km at 56kbps using 19 AWG (.7mm) twisted pair. How do Patton engineers achieve these results without using extra signal boosters or line drivers along the way?

A Little Brain, a Little Heart
According to Patton chief scientist Vladimir Herman, "We add a little bit of our brain and a little bit of our heart...analog design is art." A less philosophical engineer might have said that designing the Model 1090 blended a little intuition with a lot of painstaking calculation. However it is described, the process involved attaining the maximum signal amplification, with the minimum noise, at all frequencies, distances and wire guages. The difficulty in broadband communication (the type employed by the Model 1090) is that all frequencies in the communication spectrum must be treated differently, simultaneously, in order to attain maximum distance. So how did Patton's engineers address this difficulty?

Three Different Circuits
Without divulging anything of a proprietary nature, we can say Patton's engineers have used three types of special circuits to achieve the Model 1090's remarkable distance specifications. The first special circuit is an impedance matching circuit. This circuit matches the impedance properly between the transmitter and the twisted pair, as well as the receiver and the twisted pair, for each frequency band. Every time the quality, didtance and guage of wire is altered, this special circuit compensates for it. The second special circuit reduces the Model 1090's signal-to-noise ratio. In order to achieve great distances, the signal must be amplified greatly. But if the noise is amplified too much along with the signal, communication-garbling errors result. The Model 1090's noise reduction circuit lowers the "floor" of the noise level, effectively raising the "ceiling" so that there is more "headroom" for signal amplification. It performs roughly the same function for the Model 1090 that a Dolby (TM) or DBX (TM) noise reduction circuit performs for a home stereo.

The Third special circuit used int the Model 1090 is an auto-equalization circuit. This circuit also operates in a way that home stero enthusiasts would recognize. Audio enthusiast know that it takes a lot more power to amplify a low frequency to a particular decible level than it does for a high frequency. The same is true in broadband communication. The Model 1090's auto-equalization circuit adjusts the level of signal amplification (dynamically) to match the frequency being amplified. The result is a more uniform signal across the frequency spectrum, which helps maximize distance.

Impressive Capabilities
Combining impedance matching, noise reduction and auto-equalization circuits (along with more than a little "art"), Patton's design engineers have given the Model 1090 some impressive speed and distance capabilities. What this means to end users of datacom and telecom equipment is that the Patton Model 1090 baseband modem can provide reliable communication at high data rates/distances not normally associated with affordable "short range" solutions.