#### sh-eda

##### Member level 1

I have a general question about the standard model used for cable lossy transmission lines.

I am looking redesigning a product that drives a signals down very long cables, ie could be well over a kilometre and various configurations. (Ultimately this is due to IC obsolecence). The frequency I can use is fixed, around 100-200kHz region, as it has to work with existing system. I have been doing some testing on different types of cables and configurations to work out the various parameters (characteristic impedance and . Unfortunately I do not have access to cables this long. The maximum length I can currently test is the approx 20-30m. So I am looking at using the data I have and simulating the various cables and configurations.

The things I am finding is that the model works fine when looking a frequency response for a sinewave, but doesn't seem to work when looking at cable propagation delays and reflections. i.e for a pulse or squarewave. I am wondering whether this is true or not? or maybe I need to increase the number of inductor capacitor elements?

I am currently using Proteus ISIS, but have also tried multisim.

Thanks.