Cisco Headend System Release 2.7 Mode D'Emploi
The Reporting Option
4031374 Rev B
131
Examples of Systems Needing Recalibration
To further illustrate the value of the information contained in the DHCT Transmit
Level Saturation Report, consider these two cases. The first case, Case 1 (on page
131) depicts a system where DHCTs transmit at levels higher than our
recommended range of 25 to 55 dBmV. The graph clearly shows the excessively high
transmit levels.
Level Saturation Report, consider these two cases. The first case, Case 1 (on page
131) depicts a system where DHCTs transmit at levels higher than our
recommended range of 25 to 55 dBmV. The graph clearly shows the excessively high
transmit levels.
The second case, Case 2 (on page 132) illustrates a more subtle example of a system
needing recalibration. The graph looks fine but the chart depicts one demodulator
transmitting too low and another transmitting too high.
needing recalibration. The graph looks fine but the chart depicts one demodulator
transmitting too low and another transmitting too high.
Case 1
This example illustrates a system where DHCTs transmit at levels higher than our
recommended range of 25 to 55 dBmV.
recommended range of 25 to 55 dBmV.
The midpoint of our recommended range of 25 to 55 dBmV is about 40 dBmV. The
midpoint of the responding DHCTs depicted in the graph, and confirmed by the
data in the following chart, is about 50 dBmV-too high. Furthermore, the graph
illustrates a definite drop-off of responding DHCTs at about 55 dBmV, a clear sign
that there are additional DHCTs transmitting at levels too high to even be
recognized.
midpoint of the responding DHCTs depicted in the graph, and confirmed by the
data in the following chart, is about 50 dBmV-too high. Furthermore, the graph
illustrates a definite drop-off of responding DHCTs at about 55 dBmV, a clear sign
that there are additional DHCTs transmitting at levels too high to even be
recognized.