Question on modem event log entries

meerkathalon

Anytime my modem restarts I see the following entries. My neighborhood has not yet been upgraded for mid-split.
I thought the 1002MHz line was interesting however. The highest channel my S33 locks on to is QAM 657 and OFDM 690 which to me fits in with operating on 750 plant.

Does the 1002MHz entry indicate that my modem could actually lock on to DS channels up to 1Ghz if allowed or is this extra bandwidth reserved for tv channels?
Does anyone else here see log entries like this in low-split areas?

31/12/1969 19:00:20 3 CMSTATUS:US_Diplexer_Mode_Change_Ignored:TLV-9, 42MHz. 31/12/1969 19:00:38 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz. 31/12/1969 19:00:38 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz. 31/12/1969 19:00:38 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.

fmd

Yes, all 3.1 modems must support at least 1 GHz. 🙂

Mid-split modems usually stop at 1 GHz, high-split modems (in high-split mode) can go to 1.2 GHz, and the new 3.1+ modems can go to 1.8 GHz.

Devious

Look at the date of the log entries.
This happens during sync of the modem with the headend and is of no concern to the end user.

meerkathalon

Devious

Anytime my modem restarts I see the following entries.

Yeah, I get how default dates work…. My question was around sub split systems and if the higher end spectrum up to 1Ghz is ever used. A second OFDM could fit in this range right?

fmd

meerkathalon Yes, the standard mid-split layout is a 192 MHz OFDM from 810 to 1002 MHz - called the 1st OFDM channel (it got added first). The 2nd OFDM in this standardized layout goes from x (it varies) to 810 MHz.

It looks a bit different in FDX plants.

MacLeech

meerkathalon Newer modems appear to have 3 filters. An upstream cutoff, a lower downstream cutoff, and an upper downstream cutoff. Your modem show the upstream cutoff is at 42Mhz, the lower downstream cutoff is at 108Mhz, and the upper downstream cutoff is at 1002Mhz. Basically, it’s configured to support low split and block MOCA.

The upper diplex filter is to block off MOCA frequencies from the modem receiver, if needed. Usually it’s a switch between 1Ghz (1002Mhz) and 1.2Ghz (1218Mhz). Providers with active MOCA deployments usually set the filter to 1002Mhz. Providers with upper frequency deployed DOCSIS OFDM channels would set it to 1218Mhz.

The vast majority of hub video equipment and cable boxes are good up to 860Mhz video QAMs, but CMTSs are good for QAM frequencies above that, so 860 MHz and above frequency space is almost exclusively used for DOCSIS.

Mid-split would be 85, 108, and 1002/1218. High split would be 204, 258, and 1002/1218.