Cable return path has outside signals at 22mhz

Could be a lot of things. I remember hearing a lot of Spanish language stuff around there several years ago. Best thing is to move to a clear part of the spectrum (above 30MHz seems to be good in most plants), and use the carrier to train the line crews on finding ingress.

Thanks for the reply. As it is, our outside plant guys are the ones who bought me in, I am the inside plant /cellular tech. I showed them how to use the spec a, and then they showed me this signal around 22mhz. Seems our mad scientist on our staff found a deal on return amps, and decided that we should go into the cable modem side with our rural cable system. So the outside plant guys placed the return amps in the housings, and then our mad scientist wondered why the Motorola surfboard cable modem did not work with the c9 CMTS he also bought. I asked if we placed any high pass filters in the return, and the answer was no. I also asked if all the amps and housings were checked for proper terminations of the connectors and contacts to ensure no Common path distortion, etc, and again the answer was no. All they did was place the amps in and expected it to work. What is interesting is that at our headend, these 22mhz signals are not present on the return path. We observed them at our CO which is across the street from our rural airport. We do have a large FAA presence here, as we are like a regional hub for this part of rural Alaska, whcih is why I thought it may be some kind of radio navigation signal, as they are kind of close to that freq.

Thanks again

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Dana,

Go to

and join that list. There are many CATV engineers and technicians there who may be able to help you.

Thanks for the link.

A good starting point for getting an idea of what you are getting into is this book:

Sort of dated, but full of design theory. You can't just shove the return module in and have everything go smoothly. Also, check with your sweep meter vendor. They all have a ton of free training materials that include practical examples using the same equipment.

As for the carrier, get a sw reciever and listen for it. It might give you a few clues. But remember, a cable system has some of the best SWL antennas ever produced - nice, long drops. And they all funnel together to one place. Point a video camera at the spectrum display (or use the video out if so equipped) modulated to a pilot channel. The sweep crew can use a test set to track down the offending carrier (along with all the other trash I'm sure is in the spectrum). Will lead to a lot of surprises.

If you need a consultant, I have some vacation time available. I've always wanted to see Alaska. Have to do it before ski season, though. :)