Alpha Technologies AlphaNet IDH4 for XM2 and XM2-300HP Series - Technical Manual - Manual (Page 33)

33 746-257-B2-001, Rev. B (01/2014)
4.0 Web Interface
4.12 QAM Constellation
Select the Tools menu to access the Constellation page. Click the Constellation menu item to view the
Constellation display for the DOCSIS channel. The page will automatically refresh until the updates
remaining counter reaches 0. Clicking the Run button restarts the automatic refresh, and clicking the Stop
button stops it.
Fig. 4-20, IDH4 Constellation Page
(data values shown for illustration purposes only)
4.13 Controls
• Run — Start the sampling of data by pushing the Run button. The unit will acquire 100 samples and
then stop.
• Stop — Use the Stop button to end the sampling.
4.14 Downstream Data
• Frequency — is the downstream frequency given in Hz.
• Power — is the downstream power given in dBmV.
• SNR / (RxMER) — this is the downstream signal quality. Modulation Error Ratio (SNR); hw/ sw: ok 3140;
good 40 and higher.
• EVM —Error Vector Magnitude (from hardware MER (Modulation Error Ratio) / software MER).
• CER Interval — Codeword Error Rate (CER) refresh rate.
• Pre FEC CER — Codeword Error Rate (CER) BEFORE forward error correction is applied.
• Post FEC CER — Codeword Error Rate (CER) AFTER forward error correction is applied. Should be <
9x10E-7.
• Updates Remaining — this is the number of sample updates remaining for this session.