Confused about location of KQMK-LD in Omaha, NE market (1 Viewer)

double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
I'd like to get KQMK-LD, physical channel 21, virtual 25. Please reference RabbitEars.Info . My working antenna (see complete setup below) is pointed to the NE and I am picking up physical channels (listed in order of field strength) 26, 29, 22, 20, 31, 12, 32, 17, 15, 33, and 35. Channel 21 has a field strength less than 33 and 35, and is in the same general direction. I thought I should be able to pick it up. However, when I look at fccdata.org the station is in a different location on the map: FCCdata.org - powered by REC

There are two locations in fccdata.org. The most recent matches with rabbitears.info, another site marked as pending shows the Ashland, NE location.

Sorry I don't know how to interpret FCC application data. Where is the station right now? To the NE or NW?

My antenna setup is on a 50-foot tower and clears the local terrain by around 15'. I have an RCA ANT3038XR pointed to the NE and a Five Star Yagi 2020 Antenna pointed to the SE. They are combined with a Wineguard CC-7870 and then into a Wineguard pre-amp on mast. Currently the cables from the antenna to the combiner are not correct, they are of different lengths and pretty sure the cable to the Five Star is damaged. As soon as the wind dies down around here I'm going to replace with equal length cables. I'd like to have an idea of where to point the Five Star when I'm up on the tower. The SE direction was intended to capture the Lincoln market but turns out I won't grab any networks I don't already have and there is competing physical channels, so I'm going to move it. At least I'll point it in the same direction as the RCA and get some gain. I could point to the NW if that's really where KQMK-LD is. I'll have my phone so I can re-scan my DVR while I'm on the tower to verify my channels.

Fairly new at this, any advice is appreciated.
 

double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
I hadn't done a TV Fool report, I've only looked at the RabbitEars.info report. TV Fool is very helpful! It places the transmitter to the NW-ish, same as fccdata.org. It is 10.7 miles from me. Doing the NM calculation the value is 17.9. If the report is accurate, pointing my second antenna directly towards the transmitter should be sufficient. Looks like there are several more stations I should be able to pick up.

Since you asked about a TV Fool report I assume it's more accurate?
 

rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
I'd like to get KQMK-LD, physical channel 21, virtual 25. Please reference RabbitEars.Info ....when I look at fccdata.org the station is in a different location on the map: FCCdata.org - powered by REC
Hello, double16; welcome to the forum.

Thank you for the signal report; it helps.

The FCCdata.org shows two locations. The one dated 07/07/2020 lists the correct location which is:
Latitude: N 41° 13 ' 29.6 "
Longitude: W 95° 57 ' 10.5 "
or
41.224889, -95.952917

double16SatGuysmapKQMK2.jpg


As a double check:
RabbitEars.Info
click on Application Info
Application Search Details
click on View LMS Information for License
click on View Engineering Data for coordinates and antenna data
Sorry I don't know how to interpret FCC application data. Where is the station right now? To the NE or NW?
It's to the NE and further away.
I have an RCA ANT3038XR pointed to the NE and a Five Star Yagi 2020 Antenna pointed to the SE. They are combined with a Wineguard CC-7870 and then into a Wineguard pre-amp on mast.
Combining two antennas aimed in different directions with a CC-7870 is the same as combining two antennas aimed in different directions with a splitter in reverse. It often doesn't work because when the same signals arrive at the combiner they will interfere with each other if they are not in phase (arrive at the same instant).

If you don't have all the signals when combined that you had when the antennas were separate, that method of combining doesn't work for your location.

I sugest you try just one antenna aimed at KQMK as a test.
Currently the cables from the antenna to the combiner are not correct, they are of different lengths..... As soon as the wind dies down around here I'm going to replace with equal length cables.
When the two antennas are aimed in different directions, the cables do not need to be equal length; it's irrelevant. They only need to be equal length when you combine two identical antennas aimed in the same direction for additional gain.
At least I'll point it in the same direction as the RCA and get some gain.
Not a good idea; let just one antenna do the job.
 
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rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
Since you asked about a TV Fool report I assume it's more accurate?
The TVFool reports used to be the most accurate, but they now contain many errors because they use a database that is not up to date.

Trip, a member of this forum, the webmaster for rabbitears.info and an employee of the FCC, saw that the TVFool reports were becoming less useful. He created the rabbitears.info Signal Search Map to generate more accurate reports.
 
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double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
I reviewed the tower map and terrain map in RabbitEars.info and I should be able to receive the station. I'm receiving 35 which has less strength and more distance and is in the same direction. So I'm puzzled why I don't currently get 21, or 27 for that matter. I'll take your advice and try with only the one antenna and bypassing the combiner and see what I get. Will report back when I'm able to get up the tower.
 

rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
I'm receiving 35 which has less strength and more distance and is in the same direction. So I'm puzzled why I don't currently get 21, or 27
I looked at the Longley-Rice coverage maps for what I think is your location. The report moves the marker to protect your identity.

Since they are a computer simulation, the coverage maps aren't as accurate as implied, but KQMK shows light green. However, KQMK RF 21 is at 34.4 degrees and KHIN RF 35 is at 59.9 degrees. Antenna aim can make a difference.
 

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double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
However, KQMK RF 21 is at 34.4 degrees and KHIN RF 35 is at 59.9 degrees.

I’m not sure exactly where the antenna is pointed. I used the Wineguard app to locate a tower with augmented reality and then eye-balled it. It wasn’t the 35 tower, it’s a rebroadcast of 33 so not necessary. Pretty sure it was the three close together with 17,22,31. I have access to a good compass and will use that to align antennas.
 

double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
Still too windy to get on the tower. I did make a measurement from the ground and it's close to 40 degrees.

I also tried something for kicks and went to the top of the nearest hill and used a cheap DTV antenna in the attached picture on a cheap 13.3" TV. I got all the same channels I'm getting with my tower mounted RCA except for 12, and that's a VHF signal. Kinda surprised!

Maybe I'm putting too much on receiving channel 35. It's field strength is 57.54 and I'm picking it up on this cheap thing. Channel 21 and 27 have strengths 73.87 and 70.12, respectively. I think if I'm getting something in the same general direction at 57.54, I should get 73.87.

The application for KQMK-LD in Omaha was approved July 6th, 2020. What is the timing of licensing? Does it happen before the station is built? Seems reasonable. Perhaps KQMK-LD isn't transmitting yet?

I'm starting to think aiming at 40 degrees, where it currently is, is good enough and I'll point my second antenna according to my original plan, at 250 degrees towards Lincoln. Just doesn't seem like at this field strength 8.2 degrees will make a difference. (Too bad it wasn't such a pain to adjust it.) I will still re-scan with only the RCA connected and bypass the combiner to see what I get.

Thanks for answering my questions. I like to dig into stuff like this and try to understand.
 

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rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
I got all the same channels I'm getting with my tower mounted RCA........I think if I'm getting something in the same general direction at 57.54, I should get 73.87.
I would think so too.
The application for KQMK-LD in Omaha was approved July 6th, 2020.....Perhaps KQMK-LD isn't transmitting yet?
The rabbitears says it's on the air.
RabbitEars.Info

So, if your tuner isn't able to pick up KQMK, it's either too weak or not on the air.

The rabbitears.info site has monitoring stations that use SiliconDust HDHR tuners.
RabbitEars.Info
click on Sitemap
RabbitEars.Info
scroll down and click on
Maps > Live Bandscan
TV reception map
on right side scroll down to and click on
Bellevue, NE (about 3/4 down)
TV stations received at Bellevue, NE tuner0
on lower left scroll down to KQMK and click on graphs
Signal graphs for KQMK-LD at Bellevue, NE on tuner0

It looks like KQMK is on the air but very weak even in Bellevue. His antenna must not have much gain.

KHIN is stronger at his location.
 

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rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
After comparing the signal graphs for KQMK 21 and KHIN 35 done in Bellevue, it looks like KQMK is running at reduced power.

I wonder how you can contact the KQMK station engineer.
 
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double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
After comparing the signal graphs for KQMK 21 and KHIN 35 done in Bellevue, it looks like KQMK is running at reduced power.

That's great info, thanks! I was at a relative's house last night about 2-3 miles away from the station and I was able to get a picture on 21, just to be sure it is on the air.

I wonder how you can contact the KQMK station engineer.

The FCC application has an email, which I'm sure isn't the station engineer, but it's a start.
 
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rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
That's great info, thanks! I was at a relative's house last night about 2-3 miles away from the station and I was able to get a picture on 21, just to be sure it is on the air.
Good; that seems to confirm it's at the new location in Omaha.
The FCC application has an email, which I'm sure isn't the station engineer, but it's a start.
All I could find is HC2 Holdings:
1-800-667-0388
Help@HC2Broadcasting.com

If I was at your location, I would want to see if I could find the signal using a $25 USB dongle and SDR# (SDRsharp) software.





 

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rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
Channel 21 is 512 to 518 MHz. It's pilot carrier is at 512.310 MHz.

 

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double16

Thread Starter
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Sep 27, 2020
12
2
Nebraska
It's owned by HC2 Holdings. I checked their web site which has a list of stations and KQMK isn't there. There is a contact email for help, so I emailed today. We'll see what turns up.

I was up on the tower today and replaced the bad cable to my second antenna pointing to Lincoln. Some Lincoln stations came in and the Omaha were not adversely affected. I didn't bother scanning with only the one antenna for KQMK. I figure since it's weak in Bellevue at 3 miles, 25 miles is hopeless. (TBH, still a bit nervous on top of a 50 foot tower, so I fixed what was necessary and came down.)
 

double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
Need some more help here. Short version is I'm pretty sure my signal issues are that I'm overloading the tuners. I had thought I needed more gain. Currently my best SNR numbers are with my Five Star pointed AWAY from the stations, into the combiner, then the pre-amp. The combiner only has this antenna. The other input is open (I've learned this is probably a no-no).

I connected only my RCA with it pointed at ~40 degress, no combiner, and many of my SNR levels dropped and I lost KAJS-LD which is ~10 miles from me. (I'm using an HDHomeRun HDHR3-US scan). Then I tried my Five Star Yagi only, no combiner. Same, SNR for most stations in the <75 range and no KAJS-LD. I pointed it towards KAJS-LD, nothing. I played with the setup for 2 hours (on top of a 50 foot tower, pretty comfortable with it now ;) I pointed the antenna away from the stations, it got better, added the combiner and most stations are SNR of 80-95. Except KAJS-LD and KBIN.

As for the station I'm originally trying to get KQMK, I've had some progress with the current setup. Whereas I was never able to get a lock, now the live bandscan sees it off and on throughout the day. Last night it had a decodable signal for a few hours.

I'm thinking getting signal from the back of the antenna will have issues, like more susceptible to atmospheric events? (guessing on that). I'm more hopeful now I can get KQMK, KBIN, and KAJS reliably. The other stations are pretty strong and I don't have much issue. Am I thinking correctly that I'm overloading?

What I think is the right thing to do is to point the Five Star Yagi towards 21 degrees at KQMK. The rest of the stations are in the general direction or have a very strong signal. Take the combiner out. Attenuate the signal. I'd like to attenuate after the pre-amp because it's in the house. Possibly I'll get better quality signal aiming the antenna the correct way. Below are the signals I care about.

1604443460893.png


The Wineguard LNA-200 has a gain in UHF of 18db and NF of 1db, the antenna gain is 12db. The max input signal to the LNA-200 is 126 dBuV if the mV to dBuV calculation is correct. So probably not overdriving the pre-amp, but close. That means I should be able to attenuate after the pre-amp.

Another concern is that there are two very strong signals on either side of KQMK, 32 and 34. Would those bleed over? Anything to do about that? I guess if it bleeds over at the antenna/pre-amp I'd have to attenuate between the antenna and pre-amp. :/

Advice is appreciated!
 

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double16

Thread Starter
Member
Sep 27, 2020
12
2
Nebraska
Answered my question: the pre-amp is overloading the tuners. Turned off the pre-amp, took out the combiner, pointed the Five Star to ~20 degrees to get both KAJS and KBIN since those are the two stations I want with weaker signals. Levels look ok but could use some boost. Still no KQMK. I have attenuators on order. I'll try with pre-amp + attenuators and see what happens.

1604528306593.png
 

rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
I'd like to get KQMK-LD, physical channel 21, virtual 25. Channel 21 has a field strength less than 33 and 35, and is in the same general direction. I thought I should be able to pick it up.
Uh, no. KQMK is listed as stronger than 33 and 35.

However, KQMK on 21 is between two much stronger channels on 20 and 22. Adjacent channel interference is a possibility, if KQMK is running at reduced power. KQMK must not be any weaker than 33 dB below a stronger adjacent channel.

ATSC Recommended Practice:
Receiver Performance Guidelines

Document A/74:2010, 7 April 2010

RECEIVER PERFORMANCE GUIDELINES

5.4.2 Adjacent Channel Rejection

The receiver should meet or exceed the thresholds given in Table 5.2 for rejection of first adjacent-channel interference at the desired signal levels shown above the columns therein.

First Adjacent Channel Thresholds2.jpg
 

rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
I'm pretty sure my signal issues are that I'm overloading the tuners.
That's quite possible. The Signal Margin on a rabbitears.info report is similar to the Noise Margin on a TVFool report.

NMChartRev.jpg


If the antenna is aimed at 21 degrees, WOWT has a Signal Margin of 63 dB. If you add the antenna gain of 12 dB, you are at 75 dB, which is considered overload.

double16SatGuysReportREdBm_1.jpg


The Wineguard LNA-200 has a gain in UHF of 18db and NF of 1db, the antenna gain is 12db. The max input signal to the LNA-200 is 126 dBuV if the mV to dBuV calculation is correct. So probably not overdriving the pre-amp, but close. That means I should be able to attenuate after the pre-amp.
Listing the signals in your report by dBm, WOWT has a Signal Power of -27 dBm. If you add the antenna gain of 12 dB, that brings you up to -15 dBm. The MAX UHF input of the LNA-200 is -26.7 dBm.

Preamp_Summary3_2.jpg


The preamp and the tuner would be overloaded.
Another concern is that there are two very strong signals on either side of KQMK, 32 and 34.
Huh? I covered adjacent channel interference to 21 in a previous post. 20 and 22 are adjacent to 21.
 

rabbit73

SatelliteGuys Family
Jul 17, 2020
86
49
S.E. VA
THREE TYPES OF OVERLOAD
There are three types of preamp or tuner overload, in order of increasing signal strength:

1. The strong signals almost cause enough intermodulation distortion (IMD) to interfere with the reception of weak desired signals, but the spurious signals are at or below the noise floor of the weak signals. This is the point that holl_ands uses in his preamp charts to obtain max SFDR (Spurious Free Dynamic Range). No damage will happen.

As the strongest signals continue to increase in strength, more of the weaker signals are damaged until you reach:

2. The strong signals cause overload to the preamp or tuner that makes it impossible to receive any signals. No damage will happen. The strongest signals are still there, but they can't be decoded because the IMD products have damaged them so that they contain more errors (high BER....bit error ratio/rate) than can be corrected by the FEC (forward error correction).

3. The signals are so strong that the input transistor is toast. You are not likely to encounter OTA signals that strong, unless you live next door to a high power transmitter and you have your high gain antenna aimed at the transmitter's antenna.

As a general rule, tuners can tolerate stronger signals than preamps before overload. The difference in strength is approx. equal to the preamp gain.
 

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