dslreports logo

    All FAQs Site FAQ DSL FAQ Cable Tech About DSL Distance DSL Hurdles »»


how-to block ads

Receive: -15dBmV to +15dBmV
Transmit: 30dBmV to 55dBmV
Carrier/Noise Ratio (SNR): >30dB

The closer to the center of the spec, the better (for receive and transmit).

As you get closer to the edge of the spec, you might start to see some connectivity problems.

Note: signal strength does not really affect speed. So as long as you aren't getting disconnects/pauses/packet loss, you probably are OK, even if you are nearer the edge of the spec.

Feedback received on this FAQ entry:
  • The OOL plant build standard (enforced on the techs with an in-home test) is Receive Power from -10dBmB to +10dBmV, while transmit is up to +54dBmV (DOCSIS2 US limit for CV's 64QAM US channels) - there's no low Tx Power limit, but you're unlikely to ever encounter values lower than +30dBmV. The FAQ statement of "closer to the center = better" is blatantly and 100% wrong : the only way to accomplish that for everybody is to move every house on that node segment into the exact same location (:-). The correct statement is, and MUST be: DOCSIS will operate correctly and with acceptable error rates (BER/MER) and with no significant frame (and packet) loss anywhere in this range. Marginal values near the very edge of the spec could become problematic at times, as signal levels vary by outdoor temperature. A +54dBmV transmit power is like a problem, as modems cap their Tx power per the spec - while the headend may receive less signal than spec'd (below 0 dBmV), but this cannot be seen from the modem side. The only way to ensure that the headend is not "under water" is when the Tx Power is =< +53dBmV - that 1dB of margin is easily consumed by changing environmental conditions.

    2013-01-30 12:06:29 (cablewizzard See Profile)

Expand got feedback?

by Lex Luthor See Profile edited by drake See Profile
last modified: 2011-07-12 06:36:07