6dB Attenuator.. Better With or Without?
 

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

Re: 6dB Attenuator.. Better With or Without?
 

From reading this link, 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....html#goodlevs


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

Re: 6dB Attenuator.. Better With or Without?
 

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 :|

Re: 6dB Attenuator.. Better With or Without?
 

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?

Re: 6dB Attenuator.. Better With or Without?
 

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

Re: 6dB Attenuator.. Better With or Without?
 

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.