← Home

By modernizing your existing POTS network, 
Comtest transforms your network to a DATA network that can support POTS.

Deliver traditional phone service over your data network

When outside plant augmentation and maintenance are not enough, Comtest can help with components designed for data networks.

EMI resistance

Comtest line conditioners help solve chronic network issues using differential signalling and balancing cable-pairs.

Learn how EMI affects xDSL quality →


Innovative Comtest components give copper networks the performance boost required by the increasing demand for data network services.

How your existing network can benefit →

What is cable pair balance?

Pair balance consists of the same inductance and resistance per unit length for tip and ring as well as same capacitance and resistance of the linear wire from tip and ring to ground.

Cable pair imbalance affects xDSL

Unbalanced pairs allow EMI to thrive and can create many different problems with DSL

  • Slow modem speed
  • Modem re-sync
  • PPPoE session drops
  • Freezing or pixelation on IPTV

Comtest solution:
EMI suppressor with splitter functionality

Comtest splitters with EMI filter perform two essential functions:

  • Provide very significant common mode isolation between line and DSL port, with virtually no loss in differential mode between line and DSL port.
  • Provide needed isolation between voice and DSL band utilizing low pass filter between line port and POTS port.

Eliminate ghosts in your network

Differential signaling offers an increased resistance to electromagnetic noise.

Resistance to electromagnetic noise is achieved only if twisted pairs are balanced.

n the real word, rarely are twisted pairs completely balanced.

Figure 1 represents the average bits per tone graph without Comtest line conditioners in place; each of the red lines represents a “tone range” where data bits could not be slotted because of an interferer on the line.

Figure 2 is the same line with Comtest line conditioners in place. Significant reduction in noise and/or interferers results in higher sync rates (more tone ranges to slot data bits) and better performance overall.

PSD Distributions before EMI suppressor
Figure 1: PSD Distributions before EMI suppressor/splitter installation
Crosstalk Telecommunication Terminal Block vs
                  Comtest SA-2811-0001
Figure 2: PSD Distributions after EMI suppressor/splitter installation