Originally Posted by dbdoc
I have been aware of the newer antenna technologies. I have done well much of the time using indoor antennas, although I had a directional on a rotator in the attic of my last residence (south waldo) that I used for a couple of rooms. I definitely don't need the 20db gain of the cm. In fact, since moving to brookside last fall, I have retired one amplified indoor and modified another to bypass the amp. Omnis, like the cm, don't do as well in high multipath areas, which is definitely me. Since you can't eval reception by looking at the picture like you could analogue, I got my pro SLM. Seeing the waveforms and numbers has been an eye opener for what you can get by with or not. If I ever decide I don't want to watch any cable channels and ditch cable, I will get serious about OTA reception. Until then, I will continue to dabble, as I have since I started watching OTA HD in 2003.
I would like to know what device you refer to as a "pro SLM", my assumption is "Signal Level Meter" but that doesn't tell me much. You make a reference to waveforms, is this perhaps some type of spectrum analyzer? I have in fact used a spectrum analyzer, but I didn't have any type of calibrated antenna, so the levels are just relative to each other. The waveforms do point out rather dramatically that in most cases amplification is not only not necessary, but in fact detrimental to receiving good ATSC signals. In my first pic are shown the carriers of 18, 21,24,29,31 and half of 34. The next pic is 34, 41-42, 45, 47 and an analog carrier. The last pic shows 41-42, 45, 47 and 51. As you can see, reflections add to and subtract from the carriers. Notice 34 is about 50% stronger than others, likely due to reflections. Each "haystack" should be flat and undistorted, but in fact are rounded due to reflections. Notice 47 is barely above noise, yet I get a good lock on that station. While 51 is strong and well above the noise floor, I tend to get dropouts due to cancellations from reflections. You can see that adding gain would just make the problem worse. By the way, the antenna was a Clearstream2, using 20db of attenuation into the analyzer. The antenna is located just off Johnson Drive and Foster on the west side of a hill with no line of site to any transmitters.