R&S®SA129Z2 Telephone Filter
Key Facts
During operation, several stations are often interconnected via telephone lines to transfer audio signals and data. The lines used for this purpose are not optimally protected against electromagnetic interference.
As a result, there are often various kinds of interference on these lines, which can be divided into two categories:
- Overvoltage caused by electrostatic discharges such as lightning strikes in the vicinity of telephone lines (no direct strikes). Such transients cause short-time interference, which may cause errors during data transfer. High-energy transients can even destroy the connected terminals.
- Spurious signals due to strong electromagnetic signals caused by transmit systems such as broadcasting transmitters or radio links in the vicinity of telephone lines. Overhead telephone lines can have the same effect as antennas for such signals. If the received spurious signal is demodulated by the terminal (e.g. telephone or modem) and superimposed on the useful signal, the broadcast signal is audible in addition to the useful signal itself and often disturbs the technical evaluation of the useful signal.
The Telephone Filter R&S® SA129Z2 has been developed to counteract the two types of interference. It is looped into the telephone line near the line’s entry point in the building in front of the terminals and connected to the building earth.
