Return Path Test and Measurement Set

Return path measurement units
CIU-01 Head-end return path monitor.
The monitor is intended for measuring of pilot-signals, injected by the GPS-01s, frequency response function and spectrum in the cable segment in the return band with. Results of measurements are displayed on a built-in screen and transmited through the forward path to IT-081.

GPS-01 Return path pilot generator.
The return path pilot generator GPS-01 forms signals for measuring frequency response function, for installation and control of the cable network state.

IT-081: TV level meter.
The TV level meter IT-081 performs measuring of TV signals parameters of 5 to 900 MHz range. IT-081 displays CIU-01 measurement results when it operates with the set.

Set functioning

The generator GPS-01 connects to a cable network point where it needs to correct level or control frequency response of return path. The mode of GPS-01 is set with a computer, IT-081 or a built-in user interface. It is possible to change number of pilot-signals (up to 4) and tune pilot signal frequencies in the 5 to 65 MHz range. Signals output levels are adjusted in the 72 to 118 dBuV range with the 0,75 dB step. Pilot-signals are generated consequently in time. Every signal contains a name code of generator and some auxiliary information. Moreover GPS-01 can work in a frequency scanning mode and an unmodulated single-tone mode. All parameters of the generator are saved during power switch-off.

The monitor CIU-01 is installed in a head-end according to a current network configuration. After finding out the active pilot-generator and defining his signals frequencies, CIU-01 starts to measure pilot signal levels. After that searching of new pilot-generators, measuring both signals levels and a spectrum of return path is performed simultaneously. It is possible to have up to 8 active GPS-01 in the same network but pilot signals frequencies values have to differ each other. Results of measuring are transmitted back through the forward path.

The TV level meter IT-081, connected in any cable network point, receives data from CIU-01 and displays it. It is possible to watch a spectrum of return path or pilot signals levels of any active GPS-01.

The CIU measurement results can be read in via RS-232 interface for automatic monitoring over the cable network performance, statistics acquisition, real-time measurements and documenting the results. Documentation on the CIU communications protocol is provided upon request.