Reception in Boulder, CO Foothills

[Nascarken]

We'll I no what you mean about that wind ,I am not that far from you I am in Massachusetts do you have an outdoor amplifier ,it makes a big difference in receiveing in ARE neck of the woods, well let me tell you ,a little bit about my antenna set-up I have 2,OF the labs 30-2476 stacked side by side with,2,HDB 91xg stacked side BY side 90Ft high, with the vhf I receive,17channels,And the uhf 29 channels, I ALL most for got,the Johansson amplifier kit, it's K o o l it has one VHF in at 30B ,and two uhf at 40DB and one to the tv, WELL make sure you, guide wire the antennas,and if you need!! helping!!Hands shout,it's better with 4,hands then 2,we'll be,safe and good luck,ps when the hard work is done, you will be happy with the results,

[rabbit73]

acat:

Thanks for making the test outside without the preamp.

That eliminates that possibility.

I'm running out of ideas, and it bothers me that I can't find a solution for you.

The 751 seems to work better than the VHF antenna outside for CH9. That suggests there is a problem with the VHF antenna.

The 751 and the 8-bay seem to do better inside without a preamp for CH9. That suggests that the CH9 signal is better inside, but why?

I wonder how the VHF antenna inside would do?

[Nascarken]

We'll may be the splitter might not be the right one OR hooked up wrong,

[acat]

I have removed the splitter on more than one occasion and made a direct connection to the TV. I only use the splitter to feed the Silicon Dust Tuner & TV simultaneously. I have at one time or another removed everything from the circuit and put it back in to see the effect.

I too have been thinking of moving the VHF down from the roof inside to where the signal seems "better". The SiliconDust HDHR Tuner has some nice software that measures "Symbol Quality" as well as "Strength" and "Quality". When I checked the 46 Channels being received from the 8-bay indoors the symbol rate on CH9 and most of the others was ZERO and both signal and quality were bouncing around. I do have an extensive 2.4 & 5 GHz wireless network, but the only nearby source of interference is a Boulder County emergency services tower above me and 1 or two miles away. There could be reflected signals from the mountains in front of me I suppose. Grasping at straws a bit.

The fact that the antennas don't seem to be behaving as they are supposed to (VHF on UHF8-bay & nada on VHF) suggests that either diffraction, the local environment
or local sources of interference dominate reception. The signal reports from TV Fool & FCC both indicate I SHOULD have a signal...but I don't. I think it's time to start moving things around (and down).

[ADTech]

suggests that either diffraction, the local environment
or local sources of interference dominate reception.

I would wholly agree with that assessment. Pinning it down gets more difficult and usually requires more tools and more patience.

I think it's time to start moving things around (and down).

That's usually a good place to start. If you could get your hands on either a spectrum analyzer or the poor guy's equivalent, an SDR setup, it would speed things along tremendously as you could nearly immediately see if there are localized interference sources.

[rabbit73]

One other thought comes to mind. When I was troubleshooting cable TV distribution systems that had old lengths of RG59 connected with F-81 adapters, sometimes the high (UHF) channels were OK, but the low (VHF)channels were snowy (analog).

What was usually wrong was a bad connection at the F81 adapter. The connection LOOKED OK, but either the center conductor or the shield wasn't making contact. This created a gap that had a small capacitance which would allow the UHF signals to pass with little loss, but the low channels were attenuated because of the high reactance at low frequencies.

So I replaced the F-81 adapters or just ran a new length of RG6, and everybody was happy.

[acat]

Fortunately no F81 connectors in this setup!

I do have a Cellular Amplifier in the house (and an antenna outside) to aid with data and voice communication. I'll try taking that offline to see if it's broadcasting a signal that may be interfering. I don't know why I didn't think of that before.

SDR (software defined radio) usb sticks are pretty cheap; do you thing they would provide a handy way of evaluating signal strength with a laptop? Somehow have "radio" and "TV" in separate locations in my mind...never thought to connect the two!

[rabbit73]

Fortunately no F81 connectors in this setup!

It doesn't only happen with F-81s, it can also happen with the F connector at the end of a coax line.

If I were there with you, I would be making measurements of signals with my signal level meter (SLM) as I try different antenna locations. You can do almost the same thing with the signal strength readings from your TV and HDHR.

What ADTech was talking about is a way to locate signals that are on frequencies not used by TV transmitters that could be strong enough to interfere with TV reception. The tool that is usually used is a spectrum analyzer. but they are expensive. A SDR dongle and the appropriate software can do almost the same thing.

Forum member chris1379 just put one together. You can see his scans here starting at post #45:
Help with one VHF Channel, Page 3
http://forum.tvfool.com/showthread.php?t=15968&page=3

http://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

http://www.highdefforum.com/local-hd...r-10-00-a.html

The next step up is the RF Explorer, a small hand-held spectrum analyzer
http://j3.rf-explorer.com/42-rfe/faq...ine-discussion

[rabbit73]

If you go to Pete's SDR thread
http://www.highdefforum.com/local-hd...r-10-00-a.html

you will not see his images unless you are signed in, but will find them in the attachments below.
attachment 1 is from his post #1
attachment 2 is from his post #7
attachment 3 is from his post #10

[acat]

Rabbit-many thanks for the links & photos; it would be great to take a more quantitative approach and nice to not have to lug antennas and cables around. I'll give it a look and see if it's something I can undertake.

Over the weekend I took both antennas down from the roof and deployed them around the outside of the house in various locations. I have been using the SiliconDust software to record signal level, quality and symbol quality. The latter is supposedly the most important. I mounted the antennas on a tripod so I could rotate them easily and also tilt them vertically with some reproducibility. I put the SiliconDust software on a Windows 10 Slate so I could read the signal quality factors while standing at the antenna. This made life easier than running around.

I found a good symbol quality (nearly 100%),and signal level by pointing the VHF antenna off the 160 degree direction for channel 9, but it was very sensitive to the exact position & orientation of the antenna. This direction was towards a low hill several miles distant. I was prepared to leave well enough alone, but suddenly and inexplicably lost the signal and could not get it back. Still a mystery.

I placed the 8-bay bowtie in approximately the same position and tuned its orientation to maximize the various signal level/quality factors and it did just as well without the extreme sensitivity to pointing direction. All in all the quality (symbol level also 100%) level was high enough so that I was actually able to record! We'll see how reproducible this is.

In a separate experiment which I did first, I thought I might be able to combine the VHF & UHF signals using a Hi-low filter combiner (Blonder Tongue) but that seemed to degrade the overall signal quality so I didn't pursue it any further. Perhaps a better method of combining UHF and VHF signals exists?

So for now I'm going to see how "robust" the signal is day-to-day with the 8-bay. If it remains stable I'll mount it permanently. I am getting about 37 channels ranging from channel 7 upward including the main one, channel 9. Oddly, I cannot receive the nearby channel 24 (PBS). This has been true all along; I can either get channel 9 or channel 24, but not both. The orientation also makes no sense as I am not pointed at the Denver antenna at 160 degrees. I am pointed at perhaps 100 degrees straight out to the eastern plains. I will not be surprised to receive a few Kansas stations when atmospheric conditions are right; that has happened in the past.

[acat]

Rabbit

Thanks for the SDR references. I checked out Pete Higgins posts and Chris's use for his challenging reception via your links and this looks useful for my problem, not to mention the myriad other uses. Ordered one today from Amazon.

I've gotten bitten by the Raspberry Pi bug and looks like a turn on SDR is to follow!