Observer

Downstream vs upstream power

Hello,
I recently purchased a new modem and in setting it up I am trying to dial the signal in as perfectly as I can. I have great numbers it seems, but just wonder which is more important between upstream and downstream power.

If I have the coax coming into the house hooked directly to my modem I have an downstream power of right around 4.5-5 on all 15 channels with an SNR around 41. And the upstream power is 42.8 on all four channels.

Even though those are very good, I understand that closer to zero is better for the downstream power. So out of curiosity I hooked up a two way splitter (-3.5 dBm) to the line and sure enough I got the downstream power down to .8 - 1.2. But the upstream power goes to 46. I know those are still good, but given the choice, is either scenario better or worse? I have a cap on the other outlet of the splitter so the SNR doesn't really change at all.

And while I'm at it, is it weird to have only 15 downstream bonded channels? I thought they should be in multiples of 8. (My modem can run up to 24.) I called tech support and spoke to four different people who had never even heard of downstream channels before. They kept thinking I was asking about either wifi channels or download speed. Frustrating!
7 REPLIES 7
Expert

Re: Downstream vs upstream power

Don't worry about the levels unless the DS is higher than +10 dBmv.

 Yes a splitter will push the US up by the splitters port loss.

You don't want US above +49 dBmv, at +52 the modem is maxxed ou and US will start failing

 

 As for the 15 channels, paste the whole signal page and the error/event log. Don't reset the modem, need to see history

 There is no multiples of 8 rule other than qam shelves at the head end are configured in 8 channels per shelf

 Here we have 12 channels, I see 4 more slated for modems but unused and another 3 above that used for cable box/dvr maint/admin

 

 

Observer

Re: Downstream vs upstream power

Here is the connection page:

Startup Procedure
ProcedureStatusComment
Acquire Downstream Channel765000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
SecurityEnabledBPI+
IP Provisioning ModeIPv6 Onlyipv6Only(1)
 
Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUncorrectables
1LockedQAM25616765000000 Hz0.7 dBmV40.4 dB200
2LockedQAM2563687000000 Hz1.1 dBmV40.8 dB220
3LockedQAM2564693000000 Hz1 dBmV40.9 dB200
4LockedQAM2565699000000 Hz0.7 dBmV40.4 dB240
5LockedQAM2566705000000 Hz0.9 dBmV40.5 dB280
6LockedQAM2567711000000 Hz0.9 dBmV40.5 dB240
7LockedQAM2568717000000 Hz0.7 dBmV40.3 dB300
8LockedQAM2569723000000 Hz0.9 dBmV40.4 dB250
9LockedQAM25610729000000 Hz1.2 dBmV40.5 dB240
10LockedQAM25611735000000 Hz0.9 dBmV40.3 dB300
11LockedQAM25612741000000 Hz1.2 dBmV40.4 dB220
12LockedQAM25613747000000 Hz1.1 dBmV40.5 dB290
13LockedQAM25614753000000 Hz1.1 dBmV40.4 dB180
14LockedQAM25615759000000 Hz1.2 dBmV40.6 dB190
15LockedQAM2562681000000 Hz0.6 dBmV40.4 dB210
16Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
17Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
18Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
19Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
20Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
21Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
22Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
23Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
24Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
 
Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA25120 Ksym/sec24200000 Hz46 dBmV
2LockedTDMA12560 Ksym/sec19400000 Hz46 dBmV
3LockedATDMA35120 Ksym/sec30600000 Hz45 dBmV
4LockedATDMA42560 Ksym/sec37000000 Hz45.8 dBmV
5Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
6Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
7Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
8Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV

 

And here is the event log:

TimePriorityDescription
1970-1-1, 00:00:38Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:42Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:08Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.0;CM-VER=3.0;
2016-9-5, 04:29:11Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.0;CM-VER=3.0;
2016-9-5, 04:29:13Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.0;CM-VER=3.0;
2016-9-5, 08:39:26Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 08:39:27Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 08:39:31Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 08:39:47Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 08:39:48Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 08:39:53Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 08:40:00Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2016-9-5, 08:40:02Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:37Critical (3)SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2016-9-5, 11:58:56Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
1970-1-1, 00:00:37Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:41Notice (6)WiFi Interface [wl0] set to Channel 10 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:41Notice (6)WiFi Interface [wl1] set to Channel 153 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:46Notice (6)Honoring MDD; IP provisioning mode = IPv4
1970-1-1, 00:00:48Warning (5)DHCP WARNING - Non-critical field invalid in response ;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.0;CM-VER=3.0;
2016-9-5, 17:59:44Error (4)Missing BP Configuration Setting TLV Type: 17.8;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 17:59:44Error (4)Missing BP Configuration Setting TLV Type: 17.9;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 17:59:56Notice (6)Overriding MDD IP initialization parameters; IP provisioning mode = IPv6
2016-9-5, 18:00:09Error (4)Missing BP Configuration Setting TLV Type: 17.8;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-5, 18:00:09Error (4)Missing BP Configuration Setting TLV Type: 17.9;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
2016-9-6, 07:15:59Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:7f:b9:d6:eb:d0;CMTS-MAC=00:17:10:8c:0e:9c;CM-QOS=1.1;CM-VER=3.0;
Observer

Re: Downstream vs upstream power

Thanks for looking at it. Seems there are a lot of critical errors but I don't have a clue what any of them mean. But if it is relevant, when I log into my TWC account it shows my modem as being offline even though it is not.

Expert

Re: Downstream vs upstream power

I wonder if TWC has the wrong billing code entered for it. weird that it's starting on ch 3 and skipping 1, which could be ingress from local tv ch 48...

 What model is it?

 I see it's some sort of all in one combo

Where are you? 

Zip code?

Channels look like Ohio/KY Wv ones...

the T3 and T4 are some sort of connection or power loss along the street lines if that wasn't you disconnecting the coax.

Observer

Re: Downstream vs upstream power

I'm in 68516 and it's a Netgear C7000 modem/router combo. I did connect and disconnect the cable several times as I was playing around with the splitter so I'm not sure if there's been other disconnections besides those.

I don't have a TV subscription at all, if that matters. Just turbo internet that I might upgrade to extreme.

I also thought it was weird that it's skipping channel one altogether, but not sure about the fact that they're also out of order.

As far as the billing code, maybe that has to do with when I activated it, it didn't work online so I had to call. He was convinced it was used because somehow they already had that MAC address registered. I assured him I just bought it brand new from Best Buy so he put me on hold and then came back and had me go to a different RR website and suddenly it worked. Now when I get on my account it shows the MAC address and the serial number to be the same.
Expert

Re: Downstream vs upstream power

Don't worry about order, the "home" channel is always first, those are staggered between all users on the node to ballance loading.  I've seen systems have 3,7,12,22 DS channels. Quantity doesn't matter as long as all are good.

If you start getting frequencies and unlocked, that looks like an issue

 675 mhz which is missing, is tv ch 48, nearest one is 50 miles away and has a pretty weak level in your zip code., nothing above that, 49-50-51 are it on remaining, 52-83 is now 4G LTE, LMR and old cellular services.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3de2cb126681cf62%26t%3dALLTV2%26n%3d19

 

Observer

Re: Downstream vs upstream power

Good enough for me. Thanks!