NE Seattle

[Tristan]

http://www.tvfool.com/?option=com_wr...2c15adddacf9dc

This has been a long, very intermittent project due to time constraints. Previous answers to my posts over one year ago were very helpful in getting me this far!

Currently have a single antenna/cable run of about 30-40 feet to one TV (no plans for more TVs, but would be willing to add additional antennas which I know is likely needed). Yes there are trees in the way, nothing huge and close, and yes I'm "behind" a hill from Capital Hill/Queen Anne Hill groups (the groups at ~193 and 216 true compass direction)

I would like to get real channels: 38,48,39,31,22,33,46 (UHF, virtual 4,5,7,16,22,33,46) and 9,11 (VHF). Only desire 13 if I cannot get 22 (which co-broadcasts 13). 27 (virtual 28) would be nice, and I have gotten it at times.

Experience/trials so far:
-best success with DB4e at about 15 feet above roof (not sure that is a realistic permanent solution for me), got everything but real 38 (virtual 4) from UHF stations listed above.
-I've noticed wide variation in tuners (I've tried 3 different televisions, one DVR with built in tuner, and the HomeWorx HW180STB) with identical antenna arrangement
-I've noticed wide variation in antenna location (I have a flat roof and can easily walk around). Purchased a portable RCA TV to scan from rooftop as cheap alternative to a spectrum analyzer.
-I've noticed fairly substantial improvement if I tilt the antenna up about 15 degrees

Tentative plans to add a Y5-7-13 and aim towards 9 & 11, combined with UVSJ: VHF is not the problem (9 & 11 seem easy to get). Ideally one UHF for everything else. A few questions:

1) Anyone have experience with the Digiair Pro ATSC spectrum analyzer (or something similar?). The RCA portable TV works reasonably well, but is slow to re-scan and does not give real-time information. Pricey, but I might have crossed the obsession threshold enough to purchase.

2) I understand combining two antennas for UHF results in at least 3dB signal loss, I think that is roughly half the strength? I don't really have a good sense for how that would affect reception (does the listing of NM(dB) or Pwr(dBm) in my TVFR help predict?).

3) The XG-91 has a mast-clamp system that allows tilt up, but I'm hoping I can find an optimal site for the BD4e (or something multidirectional, maybe even DB8e). Is there any readily available clamp solution that will allow me to tilt the DB4e or DB8e up 10 or 15 degrees? (mounting the mast at an angle seems difficult and less safe).

4) It seems odd to me that stations broadcasting from very similar/identical locations with similar power could have such variability in reception... is this due to frequency differences that cause different amounts of reflection and or refraction of the signals? For example, virtual 4,5,7,16 (real 38,48,39,31) all transmit from very similar locations, with kW ranging from 500-1000... yet are all very difficult to receive from the same antenna location. Any advice?

Thank you!

[GroundUrMast]

1) Anyone have experience with the Digiair Pro ATSC spectrum analyzer (or something similar?). The RCA portable TV works reasonably well, but is slow to re-scan and does not give real-time information. Pricey, but I might have crossed the obsession threshold enough to purchase.

2) I understand combining two antennas for UHF results in at least 3dB signal loss, I think that is roughly half the strength? I don't really have a good sense for how that would affect reception (does the listing of NM(dB) or Pwr(dBm) in my TVFR help predict?).

3) The XG-91 has a mast-clamp system that allows tilt up, but I'm hoping I can find an optimal site for the BD4e (or something multidirectional, maybe even DB8e). Is there any readily available clamp solution that will allow me to tilt the DB4e or DB8e up 10 or 15 degrees? (mounting the mast at an angle seems difficult and less safe).

4) It seems odd to me that stations broadcasting from very similar/identical locations with similar power could have such variability in reception... is this due to frequency differences that cause different amounts of reflection and or refraction of the signals? For example, virtual 4,5,7,16 (real 38,48,39,31) all transmit from very similar locations, with kW ranging from 500-1000... yet are all very difficult to receive from the same antenna location. Any advice?

#1: No, I have no experience with the Digiar product. I have been quite happy with the real time signal metering functions of the SiliconDust HDHR tuners. With a WiFi connected laptop or tablet, I can manually select any channel and observe signal strength and quality in real time while at the antenna, as I adjust location and aim. http://forum.tvfool.com/showthread.php?t=820 & http://forum.tvfool.com/showthread.php?t=14059

#2: Combining two UHF antennas gets very complicated, very quickly. If the signals from each antenna arrive at the combiner so that they are in phase (the positive and negative peaks of the signals occur at the same exact instant), you can expect more power at the combiner output. But if the two signals arrive at the combiner out of phase, and equal in amplitude, they can theoretically cancel each other completely. In practice, apparent loss can exceed 20 dB. The spec sheet for the Antennas Direct DB8E may help you visualize what can happen when combining two identical antennas, aimed at the same point and when aimed in separate directions. https://www.antennasdirect.com/cmss_...s/DB8E-TDS.pdf Take a look at the various polar plots that depict the pattern and gain of the antenna as the panels are adjusted to various angles... Essentially, this is two DB4E antennas and a good broadband splitter/combiner with matched length coax cables from each section to the inputs of the combiner.


#3: None that come to mind... But scour through the hardware / mast / mounting options at 3starinc.com

#4: I can understand it seeming odd, but yes, the differences in frequency, exact antenna locations, power levels and the obstructions between the transmitting and receiving antennas all play significant roles in the differences you are observing. The wave lengths are all less than 3 meters... and the UHF frequencies are all less than 1 meter. As a result moving the antenna just a few inches can produce very noticeable changes in reception.

[ADTech]

combining two antennas for UHF results in at least 3dB signal loss, I think that is roughly half the strength?

It's actually twice that, or about 6 dB, before device inefficiency and phasing losses if the antennas are aimed in different directions.

Is there any readily available clamp solution that will allow me to tilt the DB4e or DB8e up 10 or 15 degrees?

Have a muffler shop nearby with a bending machine? Have them bend a custom pipe with one or more angles so that you can experiment with various elevation aims.

is this due to frequency differences that cause different amounts of reflection and or refraction of the signals?

Among other things, yes. The different frequency signals will have slightly different path impairments which will result in significant scattering of the signals by the time the diffract and/or reflect.

[Tristan]

Originally Posted by GroundUrMast

#1: No, I have no experience with the Digiar product. I have been quite happy with the real time signal metering functions of the SiliconDust HDHR tuners. With a WiFi connected laptop or tablet, I can manually select any channel and observe signal strength and quality in real time while at the antenna, as I adjust location and aim. http://forum.tvfool.com/showthread.php?t=820 & http://forum.tvfool.com/showthread.php?t=14059

Great idea! If I understand correctly, the antenna signal is received by the SiliconDust unit which then distributes via Wifi (or ethernet)... so I can stand on my rooftop and watch the signals on my laptop in real time. Anyone with experience with the iOS app(s)? Do they have the same signal meter functions? Mac version of the software?
Another thought I was contemplating: the HomeWorx HW180STP has a pretty nice signal meter... I might try attaching to my RCA TV, then I can run the HomeWorx receiver from an inverter/car battery that I have. I can accomplish this with no extra purchases, although the concept of streaming TV signals to computers/devices is intriguing

Originally Posted by GroundUrMast

#2: Combining two UHF antennas gets very complicated, very quickly...

I think I'll try to stay away from this can of worms

Originally Posted by GroundUrMast

#3: None that come to mind... But scour through the hardware / mast / mounting options at 3starinc.com

Thanks, I'll look over what they have! I wonder if I can attach a short connector pipe to something like this:
http://www.3starinc.com/universal_sw...ase_mount.html
with another mount on the connector pipe, allowing me to mount the DB4e or DB8e upright (and the use the swivel base mount to tilt upward slightly). This may get too rickety...

Originally Posted by GroundUrMast

#4: I can understand it seeming odd, but yes, the differences in frequency, exact antenna locations, power levels and the obstructions between the transmitting and receiving antennas all play significant roles in the differences you are observing. The wave lengths are all less than 3 meters... and the UHF frequencies are all less than 1 meter. As a result moving the antenna just a few inches can produce very noticeable changes in reception.

Makes this project challenging... not sure I'll be able to find the one spot to receive everything I want

Thank you again.

[Tristan]

Originally Posted by ADTech

Have a muffler shop nearby with a bending machine? Have them bend a custom pipe with one or more angles so that you can experiment with various elevation aims.

Also a great idea! I can play around with adjusting the angle before getting a shop to bend a pipe (I have a non-penetrating mount that I can wedge upward, or I also have a J-mount attached to a piece of plywood that can be adjusted to different inclinations for testing.

[GroundUrMast]

I've got the HomeWorx 150 and have found the signal metering easy to use as well.

[Stereocraig]

Does anybody have a recommendation for a USB tuner w/ selectable channel and a signal strength/ quality meter?

[Tristan]

Originally Posted by Stereocraig

Does anybody have a recommendation for a USB tuner w/ selectable channel and a signal strength/ quality meter?

I have no experience with this (Hauppauge WinTV HVR 950; a tuner in USB stick format):
http://goo.gl/OGZrjb

Anyone else? Does the software have signal strength/quality metering? According to Hauppauge website this model should work with PC or Mac

[Tristan]

I finally revisited this project and just tried the Antennas Direct ClearStream 2V on a 15 feet mast run to the HomeWorx 150 and as predicted altitude is my friend. I was really hoping to avoid guy wires, but the results are so much better than anything else I've tried that I'll eventually proceed. Reception results included watchable channels of EVERYTHING I listed (exception: real channel 13, which is located in Bremerton (Gold Mountain) quite a bit to the west of the other transmitters... but 13 comes in on RF25 which I get). Best of all: my Samsung TV pulls all those channels in directly, so no need for an intermediate box. Previously I suspected the tuner was inferior, but I think it just requires a high quality signal before displaying anything at all.

Thanks again to everyone on this forum, including but not limited to GroundUrMast and ADTech who always provide prompt helpful discussion!