How test the end of a coax cable run to see if signal being transmitted?

Andrew,

Thank you for the quick reply and ideas. Two items:

1) Can I use the 'cable toner' alone, at the cable endpoint, at the wall outlet?

Yes, I had run across the 'cable toner' ideas (see, https://www.amazon.com/Stanz-Pocket-coaxial-tracker-finder/dp/B01KZ0PL44/ref=sr_1_6 keywords=cable+toner&qid=1548095193&sr=8-6),

but the YouTube, etc. instruction videos on how to use it, if I got it right, require that you disconnect the cable at the start point and add the 'toner'. Since these RG6 cables have been messed around with over time and new ceilings, etc. I am pretty confident that there are spittters out of sight, hence, my concern to just deal with the cable endpoint location. 

Your knowledg on this 'cable toner' is much appreciated.

Thanks.  John

P.S.:  2) disconnecting the modem (messy), moving it around, hmmm, seems doable, but less preferred if a 'cable toner' will do the job.

Andrew,

IF there was not a splitter involved (and some/most of the runs should not have a splitter involved),

would the cable toner still work if only used at the endpoint wall outlet to identify a cable that has a signal OR any other low investment equipment comes to mind that also does this?

Thank you.

John

Hi,  Comcast was just here and told me I need an electrician to test the cable running for the splitter (outside) to cable outlet in the house.  Can any electrician test the cable or is there a specific type?