Current VM downstream SNR advice?
 

Hi,

I recently contacted VM broadband tech support having suffered a drop-off in BB performance (feels like a latency/packet loss prob). I included the following status info from my cable modem and suggested the cause could be a low d/s SNR:

D/S status page:
Downstream Lock : Locked
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM256
Downstream Interleave Depth : 32
Downstream Receive Power Level : -4.0 dBmV
Downstream SNR : 25.1 dB

U/S status page:
Upstream Channel ID : 1
Upstream Transmit Power Level : 49.0 dBmV
Upstream Symbol Rate : 2560 Ksym/sec
Upstream Frequency : 25800000 Hz
Upstream Mini-Slot Size : 2

I received a reply saying "The minimum SNR varies in different regions. In your region it is between 25dbmv - 33dbmv for QAM256". The sticky post on the topic in this forum says the recommended SNR is 33 for the Langley platform. Should I regard 25.1dB as acceptable and unlikely to be the cause of my problems?

Also provided the following ping info:

Pinging www.bbc.net.uk [212.58.253.70] with 32 bytes of data:

Ping statistics for 212.58.253.70:
Packets: Sent = 57, Received = 54, Lost = 3 (5% loss),
Approximate round trip times in milli-seconds:
Minimum = 44ms, Maximum = 2749ms, Average = 252ms

And 3 tracerts similar to this:

Tracing route to www.bbc.net.uk [212.58.251.195]
over a maximum of 30 hops:

1 1 ms <1 ms <1 ms xxx
2 6 ms 23 ms 26 ms 10.247.28.1
3 39 ms 40 ms 38 ms 80.4.118.25
4 40 ms 40 ms 41 ms 62.252.64.85
5 40 ms 41 ms 39 ms 213.107.47.102
6 42 ms 42 ms 39 ms 213.105.175.153
7 52 ms * 41 ms 62.253.185.117
8 45 ms 45 ms 43 ms 62.253.185.98
9 45 ms 44 ms 45 ms 62.253.185.78
10 45 ms 49 ms 45 ms 212.58.238.189
11 * 45 ms 48 ms 212.58.238.149
12 46 ms 45 ms 49 ms 212.58.239.62
13 43 ms 44 ms 44 ms 212.58.251.195

Still following up with support, but wondered if anyone can comment on the SNR question and how reasonable that ping and tracert info is.

Thanks for any advice!

Nick

Re: Current VM downstream SNR advice?
 

The Downstream Receive power looks to be quite low at -4.0dBmV and I would call up Tech Support for that on 0906 212 1111 and they are available 24/7 as well.

SNR is borderline but the power level is of more concern.

Below is the recommended power levels for both NTL Platforms and you are much lower than both of them.

Bromley (exCable & Wireless) Downstream power levels +6dB to +8 (QAM 64) +2.5 to +5.5 (QAM256)

Langley (NTL area) Downstream power levels -2.5dB to +2.5 (QAM 64) -1.5 to +2.5 (QAM256)