RabbitEars Search Map Enters Public Beta - Page 2 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 34Likes
Reply
 
Thread Tools
post #31 of 41 Old 07-30-2019, 08:01 AM
AVS Forum Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Hereford, AZ
Posts: 6,068
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1798 Post(s)
Liked: 427
The map for my location doesn't show all the stations. On Mt. Bigelow it shows KTTU, KMSB, KVOA and KOLD. I believe these stations share the same antenna. The rest of the stations that have their own antennas do not show up on the map: KGUN, KUAT, KUVE, KFTU-CD, KUDF-LP and K35OU. I would have expected all these stations to show up when I clicked the red icon for Mt. Bigelow. Also, KHRR and KUVE-CD, which are in the same location as KOLD (RF 13), don't show on the map.
Calaveras is offline  
Sponsored Links
Advertisement
 
post #32 of 41 Old 07-30-2019, 03:38 PM - Thread Starter
AVS Forum Addicted Member
 
Trip in VA's Avatar
 
Join Date: Jun 2003
Location: Alexandria, VA, US
Posts: 17,049
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1783 Post(s)
Liked: 784
Quote:
Originally Posted by Calaveras View Post
The map for my location doesn't show all the stations. On Mt. Bigelow it shows KTTU, KMSB, KVOA and KOLD. I believe these stations share the same antenna. The rest of the stations that have their own antennas do not show up on the map: KGUN, KUAT, KUVE, KFTU-CD, KUDF-LP and K35OU. I would have expected all these stations to show up when I clicked the red icon for Mt. Bigelow. Also, KHRR and KUVE-CD, which are in the same location as KOLD (RF 13), don't show on the map.
Did you zoom in? They're close together, and it was designed to only group stations that were on the same tower.

- Trip

N4MJC

Comments are my own and not that of the FCC (my employer) or anyone else.

RabbitEars

"Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

Trip in VA is online now  
post #33 of 41 Old 07-30-2019, 06:26 PM
AVS Forum Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Hereford, AZ
Posts: 6,068
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1798 Post(s)
Liked: 427
Quote:
Originally Posted by Trip in VA View Post
Did you zoom in?
Okay. So you've got to zoom in a lot for closely spaced towers. I did zoom in before but not enough.


Quote:
Originally Posted by Trip in VA View Post
They're close together, and it was designed to only group stations that were on the same tower.
I made the incorrect assumption that when zoomed out all the stations would appear under one icon and then at some point when zooming in multiple icons would appear with the stations broken out. That's probably too difficult to implement.
Calaveras is offline  
Sponsored Links
Advertisement
 
post #34 of 41 Old 07-30-2019, 06:28 PM - Thread Starter
AVS Forum Addicted Member
 
Trip in VA's Avatar
 
Join Date: Jun 2003
Location: Alexandria, VA, US
Posts: 17,049
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1783 Post(s)
Liked: 784
Quote:
Originally Posted by Calaveras View Post
I made the incorrect assumption that when zoomed out all the stations would appear under one icon and then at some point when zooming in multiple icons would appear with the stations broken out. That's probably too difficult to implement.
Yeah, unfortunately, that's beyond my skill level.

- Trip

N4MJC

Comments are my own and not that of the FCC (my employer) or anyone else.

RabbitEars

"Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

Trip in VA is online now  
post #35 of 41 Old 08-02-2019, 01:11 PM
AVS Forum Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 6,199
Mentioned: 38 Post(s)
Tagged: 1 Thread(s)
Quoted: 959 Post(s)
Liked: 531
Accuracy of the 1-deg (30-m) SRTM Database (Shuttle Radar Topography Mission on STS-99 in Feb2000) was evaluated and found to have an absolute horizontal circular accuracy of less than 20-m and height accuracies of 16-m (absolute) and 10-m (relative):
https://pdfs.semanticscholar.org/55a...294f9b1fc1.pdf
https://en.wikipedia.org/wiki/Shuttl...graphy_Mission

In the past [pre TV-Fool], I extensively used the RADIO MOBILE Propagation Prediction Program (PPP) to Automatically Download and Display the 1-sec SRTM Data [and 3-deg (90-m) for those areas 1-deg is NOT available, primarily outside of USA].....and/or SAT Images & Topo Maps. It uses same Longley-Rice Propagation Prediction Model and SRTM as TVFool. BTW: Last summer, when Lava was threatening Homes (~700 lost) on the Big Island of Hawaii, I think I could make better predictions of likely Lava Flows than the "stream line" maps put out by USGS:
http://radiomobile.pe1mew.nl/?How_to:Wineownload

And NO, it can NOT resolve the 60-ft high Hill in my backyard that completely blocks reception of my local CBS (Ch8) & ABC (Ch10) stations [all prediction programs are WRONG]. So I figure they "smear" out PPP calculations over an area about 1/2 [maybe a 1/4?] of a Football Field size.

There are other ways to Download (and also View) SRTM Data Files, incl. the following:
https://www.gislounge.com/download-3...lick-interface
https://gisgeography.com/free-gis-software

Last edited by holl_ands; 08-02-2019 at 01:36 PM.
holl_ands is offline  
post #36 of 41 Old 08-02-2019, 06:28 PM - Thread Starter
AVS Forum Addicted Member
 
Trip in VA's Avatar
 
Join Date: Jun 2003
Location: Alexandria, VA, US
Posts: 17,049
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1783 Post(s)
Liked: 784
TVStudy uses the NED data, not SRTM, as its underlying terrain data. (TVStudy powers the RabbitEars Search Map.)

- Trip

N4MJC

Comments are my own and not that of the FCC (my employer) or anyone else.

RabbitEars

"Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

Trip in VA is online now  
post #37 of 41 Old 08-03-2019, 12:22 PM
Advanced Member
 
gbynum's Avatar
 
Join Date: Dec 2006
Location: Greenville SC
Posts: 627
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked: 40
Quote:
Originally Posted by Trip in VA View Post
TVStudy uses the NED data, ...
Just teasing you, but didn't know what NED was, so googled it ... "What happened to the National Elevation Dataset (NED)?
NED data are still available and being updated continually, but the ‘NED’ terminology has been retired. The national DEM layers previously referred to as the ‘NED’ are now branded as 3DEP seamless DEMs. These seamless national DEM layers are just a few of the datasets offered in the broader suite of 3DEP elevation products."

Now I know less than before ... <grin>
gbynum is offline  
post #38 of 41 Old 08-06-2019, 01:46 AM
Member
 
Join Date: Sep 2018
Posts: 92
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 35 Post(s)
Liked: 14
I recommend this topic/thread be included as a "sticky" for easy reference.
budh9534 is offline  
post #39 of 41 Old 08-07-2019, 04:27 PM
AVS Forum Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 6,199
Mentioned: 38 Post(s)
Tagged: 1 Thread(s)
Quoted: 959 Post(s)
Liked: 531
There are a variety of Datasets available, each with a different Resolution (and hence Size of the Database). BTW: Here are "specs" for the Multi-Source National DEM (aka NED):
https://pubs.usgs.gov/tm/11b9/tm11B9.pdf

Horizontal Resolution
1.The 1/3-arc-second DEM has a ground spacing of approximately 10 meters north-south, but variable spacing east-west depending on latitude. 2.The 1-arc-second DEM has a ground spacing of approximately 30 meters north-south, with variable spacing east-west. 3.The 2-arc-second DEM has a ground spacing of approximately 60 meters north-south; east-west spacing can vary from 35 meters in southern Alaska to 20 meters in northern Alaska.

Horizontal Accuracy
The horizontal accuracy varies by the horizontal accuracy of the source data. In most cases, the horizontal accuracy of seamless DEM coverage produced from 3DEP technologies is expected to be 1 meter or better (Gesch and others, 2014). DEMs created from lidar data and legacy topographic data are particular cases that require more explanation regarding their horizontal accuracy.


Since NED, et.al. were originally intended to Scan and Merge Info from various Topo Maps (e.g. mostly 15-sec and 7.5-sec Quad maps, based on various OLD Surveying Expeditions with Sextants & Height Rods, KNOWN to have significant ERRORS), I've always been very skeptical re. ABSOLUTE Horizontal Accuracy compared to GROUND TRUTH. And BTW: Many of those Topo Maps are WAY TOO OLD and wouldn't show the results of recent grading...such as might have occurred in the past decade....or decades. And the above "Accuracy Description" doesn't help.....and even when they have Hi-Rez LIDAR [presumably for very limited areas], what then is the ABSOLUTE Horizontal Accuracy????
https://www.e-education.psu.edu/natureofgeoinfo/book/export/html/1835
https://iocm.noaa.gov/iwg/jan_2011/Jan2011_OCM_Inventory_NED_Evans.pdf [Esp. see pg29 re DATE of Source Maps]

=============================================
Which is why I prefer SRTM [1 Arc-Sec Database with 30-m Resolution], which is a CONSISTENT SET of ACTUAL Measurements [Space Shuttle Radar In Orbit], with Absolute Accuracy determined via various measurement verification efforts compared to GPS/DGPS, et.al....

Per fol., TVStudy uses a 1 Arc-Sec Database with 30-m Resolution (i.e. LSB)....or about 1/2 to 1/4 of a football field...and Absolute ACCURACY still UNKNOWN:
https://www.google.com/url?sa=t&rct=...mcWJfpnNgoON2z


Last edited by holl_ands; 08-07-2019 at 05:01 PM.
holl_ands is offline  
post #40 of 41 Old 03-11-2020, 10:33 AM - Thread Starter
AVS Forum Addicted Member
 
Trip in VA's Avatar
 
Join Date: Jun 2003
Location: Alexandria, VA, US
Posts: 17,049
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1783 Post(s)
Liked: 784
Digging this up again, I'm wondering if there's someone willing to work with me to validate my earth curvature math for the terrain path profiles. I have recently become convinced that it's still not quite right, and is now showing somewhat too much curvature. Is there anyone who might be willing to eyeball it for me and lend a hand?

- Trip

N4MJC

Comments are my own and not that of the FCC (my employer) or anyone else.

RabbitEars

"Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

Trip in VA is online now  
post #41 of 41 Old 04-01-2020, 04:51 AM - Thread Starter
AVS Forum Addicted Member
 
Trip in VA's Avatar
 
Join Date: Jun 2003
Location: Alexandria, VA, US
Posts: 17,049
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1783 Post(s)
Liked: 784
I've made some upgrades to the RabbitEars Signal Search Map.

First, I've upgraded the entire RabbitEars site from PHP 5.6 to PHP 7.4, which should improve performance and security. This was quite a slog since most of the site's database query code was written with the older "mysql_*" functions rather than the newer "mysqli_*" functions. I've not found anything broken, but let me know if you do.

Second, I've added two features that had been requested. The receive height above sea level is now given next to the receive height above ground, and there is now an option to hide stations that are believed to the be off the air. I've also rearranged some of the rows a bit, having swapped the link to the instructions to the top since a lot of people were missing it, and moving the search coordinates to be above the date and time rather than below.

There are two additional features in the works.

Already done from a code perspective but not sure how to get it into the UI, I've written a feature that will let you cut off the list of retrieved rows from the search results by field strength. The use case is if you are sorting by RF Channel and want to show only signals that are above the "Bad" region, you would put in 41 and get out only a list of stations that are "Poor" or better. It should make the results tidier in those cases.

The second is a long-discussed feature to expand the search distance from within a completed study. I worked out how to do it without potentially leaking the coordinates, and have actually written the code for it. It is designed to filter out records found in the existing study so they don't get rerun, saving resources. This code is mostly done as well, and I've figured out how to get it into the UI (the search distance value will be replaced with a drop-down menu); the problem is how to make it match up rows properly if the database has changed, as it does each day. My initial thought was to make it so you could only do the updates before the database updates, but that update happens in the 6:30-7:00AM ET time frame each day, and could result in a case where someone posts a result late at night, particularly on the west coast, and then by the time people are reviewing it the next day, it's impossible to expand the result. It mostly works properly, as long as the rows haven't changed. But if a station files a license to cover, for example, you could end up with two identical rows in a result. Maybe it's just not a big deal, but I'd rather not confuse people with it if I can help it. I think it needs some more attention before I make it public.

Anyway, thoughts and opinions and bug reports appreciated.

- Trip

N4MJC

Comments are my own and not that of the FCC (my employer) or anyone else.

RabbitEars

"Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

Trip in VA is online now  
Sponsored Links
Advertisement
 
Reply HDTV Technical

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off