"Walter R." wrote in
:

If you use a cable modem or black box, most have a built in feature
that you can access from your computer. If I type in
http://192.168.100.1/ ,I get the current signal level at my cable
modem (plus s/n ratios etc.). Mine varies from -3 to -8 dbmv.

Comcast has probably a similar setup. If they have a "help" group, ask
there.

A TV is worthless as a signal level indicator. TV frequencies are in
the 100-300 MH range, whereas the cable uplink is around 600-900 MH, a
different ballpark. You may have great TV reception but your cable
connectivity may be terrible.

A cable modem is not going to tell you that the cable has excessive
attenuation at certain bands of frequencies like a SLM or spectrum analyzer
will.Modern cable bandwidth is 1 Ghz now.
SLMs will also tell you signal-to-NOISE ratio(SNR),another important
measurement. -calibrated- measurements.
Modern SLMs will measure individual channels,groups of channels,or give you
a display of the gain slope for the entire bandwidth.
Cable drops are not flat in response,attenuation increases with frequency.

--
Jim Yanik
jyanik
at
kua.net