6dB Attenuator.. Better With or Without?

[Tuftus]

Hi all,

After having probs of late with SACM dropping connection and rebooting and all, I searched these forums....

After speaking to Tech Support they said it was an SNR prob, so after some more searching I found some post regarding the attenuator on the back of the modem.

My question is this, am I better off with or without the 6dB Attenuator?

With Attenuator -

System up time = 2 days 05h 37m 08.00s
Ethernet carrier sense xmit errs.1 = 45
Downstream channel ID = 0
Downstream channel frequency = 402750000 Hz
Downstream received signal power = -7.8 dBmV
Upstream channel ID = 2
Upstream channel frequency = 22000000 Hz
QoS max upstream bandwidth = 256000 bps
QoS max downstream bandwidth = 1536000 bps
SigQu: Signal to Noise Ratio = 28.8 dB
Cable modem status = Operational
Upstream transmit signal power = 36.2 dBmV
Date and Time = 2004-08-31,17:11:39.0
Configuration filename = ntlhm120-gold.cm

Without Attenuator -

System up time = 0 days 00h 00m 40.00s
Downstream channel ID = 0
Downstream channel frequency = 402750000 Hz
Downstream received signal power = -1.1 dBmV
Upstream channel ID = 2
Upstream channel frequency = 22000000 Hz
QoS max upstream bandwidth = 256000 bps
QoS max downstream bandwidth = 1536000 bps
SigQu: Signal to Noise Ratio = 29.3 dB
Cable modem status = Operational
Upstream transmit signal power = 31.0 dBmV
Date and Time = 2004-08-31,17:13:46.0
Configuration filename = ntlhm120-gold.cm


Any comments would be much apperciated...

Best regards

Tuftus

[Tezcatlipoca]

From reading this link (http://homepage.ntlworld.com/robin.d.h.walker/cmtips/signal.html), I think that your downstream & upstream power levels are better off without the attenuator. The SNR is also slightly better without the attenuator, but not by much (as it's still under 30dB).

http://homepage.ntlworld.com/robin.d.h.walker/cmtips/signal.html#goodlevs


But I'm no SACM techy, so hopefully an actual ntl person will be along soon...

[Ignition]

Keep it off far better without it.

Nice to see ntl invest in quality equipment, the alledged 6db FORWARD path attenuator supplies 5.2db of return path attenuation as well, pants :|

[Stu038]

Keep it off far better without it.

Nice to see ntl invest in quality equipment, the alledged 6db FORWARD path attenuator supplies 5.2db of return path attenuation as well, pants :|

Of course there is always the possibility that it is what it says on it, an attenuator rather than a forward path equaliser or cable simulator ;)

Tuftus, if its a round tubular thing then see what how things are over a few days without it, if its rectangular then it was installed for a reason other than just dropping the levels so it may be better to leave it in and get a service call.

You say that your having problems with the modem dropping the connection but the log shows 2 days of uptime, so how often is it dropping and what are the lights doing on it when you do lose service?

[Tuftus]

Thanks for all the replies and feedback...

I can confirm that it is a rectangular block and is labelled as a 6dB Forward Path Attenuator.

It has not dropped the connections for a couple of days, however browsing was quite slow so I thought I would take it off to see if that improved things.

I will keep an eye on it for a couple of days and see how it goes.

Also, is it just me or are there a lot of posts re power levels just of late?

Cheers

Tuftus

[Ignition]

Of course there is always the possibility that it is what it says on it, an attenuator rather than a forward path equaliser or cable simulator ;)

Shush lemme rant in peace :p

Last time I saw an attenuator it was described as a forward path attenuator, didn't realise that they had such an effect on return path as well.