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TDR Tutorial and Riser Bond TDR Product Review



The TDR can be a very useful tool when tuning up a new cell site. Within a single cell there may be as many as six antenna cables with multiple transmit antenna cables and multiple receive antenna cables.

Upon installation, it is easy for the construction crew to get these cables mixed up. They are usually more intent on safely making all the right mechanical connections, rather than making sure the cables are connected to the proper antennas. On the other hand, the site operator is very interested in the accuracy of matching cables to antennas.

The waveform type TDR can easily distinguish between receive antenna cables and transmit antenna cables. With the noise filter turned off, connect the TDR to the transmission cable with an antenna in place, zoom in and study the waveform. A very noisy waveform will be seen. The RF signal from the antenna will show up on the TDR baseline as noise. A relatively high gain antenna, such as the receive antenna, will have more signal amplitude than a relatively low gain transmit antenna. This difference in amplitude allows distinction between receive antennas and transmit antennas and make sure they are not mislabeled and swapped.

If it is necessary to see the actual waveform of the cable under test even with the antenna connected, simply turn the instrument on and step through the TDR's noise filters . The TDR' s noise filters will remove most of the RF signal even in a relatively high RF energy level environment.

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