Modem Settings - Slow Service sometimes - ur view?
 

Hey all,

Been confused about these settings, decided to check them up afer i have been getting slow service sometimes, at around 4-6mbit. Thing is i used to have ntl back in the 512k days with a terayon modem with a little adapter on the back between the line and the modem reducing/increasing the power i think (attenuator). Never had any problems with service in those days but it was only 512k.

Recently i have had 10mbit VM/NTL installed and i asked the engineer about the adapter and he checked it and said i didn't need it, even though no cables or anything have been changed. I was wondering if these settings could explain anything? maybe my reduced speeds sometimes? or is it all due to maintenance and upgrades due to internal network congestion in my case, doesn't help being a student place, oxford.

Cable Modem Downstream
Downstream Lock : Locked
Downstream Channel Id : 1
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM64
Downstream Symbol Rate : 5056.941 Ksym/sec
Downstream Interleave Depth : taps32Increment4
Downstream Receive Power Level : -11.9 dBmV
Downstream SNR : 29.4 dB - 30.1 db

Cable Modem Upstream
Upstream Lock : Locked
Upstream Channel ID : 5
Upstream Frequency : 34000000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 50.0 dBmV
Upstream Mini-Slot Size : 2

Any help much appreciated, thank you! :)

Re: Modem Settings - Slow Service sometimes - ur view?
 

It all seems ok, although the Downstream SNR seems a bit low - should be anything over 30dB otherwise you can suffer reduced performance, ie. the higher, the better. I remember reading this on the Virgin website somewhere. Mine is constantly above 31dB and runs fine. Expect the occassional drop, but if it persists you should contact Virgin.

---------- Post added at 03:49 ---------- Previous post was at 03:48 ----------

Downstream Lock : Locked
Downstream Channel Id : 1
Downstream Frequency : 586750000 Hz
Downstream Modulation : QAM64
Downstream Symbol Rate : 6952 Ksym/sec
Downstream Interleave Depth : taps12Increment17
Downstream Receive Power Level : -7.7 dBmV
Downstream SNR : 31.3 dB

---------- Post added at 03:49 ---------- Previous post was at 03:49 ----------

Mine^

---------- Post added at 03:51 ---------- Previous post was at 03:49 ----------

Oh, I'm not sure about any of the other settings. The DSF is right, though. =)

Re: Modem Settings - Slow Service sometimes - ur view?
 

downstream status

Downstream Lock : Locked
Downstream Frequency : 586750000 Hz
Downstream Modulation : QAM64
Downstream Interleave Depth : taps12increment17
Downstream Receive Power Level : 4.9 dBmV
Downstream SNR : 31.3 dB

Upstream status

Upstream Channel ID : 2
Upstream Transmit Power Level : 43.0 dBmV
Upstream Symbol Rate : 2560 Ksym/sec
Upstream Frequency : 37500000 Hz
Upstream Mini-Slot Size : 2

Re: Modem Settings - Slow Service sometimes - ur view?
 

As has been said previously your downstream SNR is a little low and rcv power level is a little out (depending on what type of modem you have). I would suggest that you check the levels when service is slow and when service is fine. If the levels do not change then it's possibly a red herring and more an issue with erroring or upsream SNR on the HFC (these can only be monitored from the uBR by VM)

I can see however that you are in a QAM64 area so this is possibly just an issue with utilisation and nothing to do with your levels specifically.

Below are my downstream stats for comparison, I am using a NTL 250 :


Cable Modem Downstream
Downstream Lock : Locked
Downstream Channel Id : 0
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 5360.537 Ksym/sec
Downstream Interleave Depth : taps32Increment4
Downstream Receive Power Level : 1.1 dBmV
Downstream SNR : 40.5 dB

Cable Modem Upstream
Upstream Lock : Locked
Upstream Channel ID : 2
Upstream Frequency : 18384000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 54.0 dBmV
Upstream Mini-Slot Size : 2

Re: Modem Settings - Slow Service sometimes - ur view?
 

um, i have a vm 255 modem, i thought the DRPW was a bit high/low. :/

Don't i need an attenuator? i had one before, now this install they just left it.

Re: Modem Settings - Slow Service sometimes - ur view?
 

I get brilliant speeds at most times, with a Virgin branded NTL 250, here's mine:

Downstream Lock : Locked
Downstream Channel Id : 51
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 5360.537 Ksym/sec
Downstream Interleave Depth : taps32Increment4
Downstream Receive Power Level : 8.6 dBmV
Downstream SNR : 40.5 dB

Upstream Lock : Locked
Upstream Channel ID : 4
Upstream Frequency : 36800000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 50.5 dBmV
Upstream Mini-Slot Size : 2