Cisco Systems UBR7225VXR Measuring the Downstream RF Signal at the Upconverter Output

Chapter 4 Connecting the Cisco uBR7225VXR Router to the Cable Headend

Measuring the Downstream RF Signal

Figure 4-5 Measuring the IF Channel Power Using Video Averaging

Note The approximate in-channel peak-to-valley flatness may be verified using the spectrum analyzer’s video averaging feature. Be aware, however, that amplitude values registered while in the video averaging mode are typically around 2.5 dB below the actual channel power.

Measuring the Downstream RF Signal at the Upconverter Output

Step 1 Disconnect the spectrum analyzer from the cable interface line card downstream connector.

Step 2 Connect the downstream output of the cable interface line card to the upconvertor input connector.

Step 3 Connect the spectrum analyzer to the RF output of the upconverter. If your spectrum analyzer input is overloaded, you might see artifacts that are internally generated by the spectrum analyzer. The artifacts are circled on the analyzer trace shown in Figure 4-6. Add attenuation as necessary to correct the overload condition.

Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide

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