Lookup TV Signals by Address | Hacker News Reader

Lookup TV Signals by Address

tvfool.com

28 points1970-01-0114 comments

IIRC, TVFool was not kept up to date with the FCC repack station moves. I wouldn't recommend using it as its predictions are likely to be inaccurate. This is a better tool that is continuously updated:

https://www.rabbitears.info/searchmap.php

The source of all other tools: https://www.fcc.gov/media/engineering/dtvmaps

This reminds me of a problem that I have yet to figure out - does anyone know of any working GNURadio flowgraph which can decode and display ATSC 1.0 television in real time? I don't want to record now and watch later, for the purposes of this question.

It's built into GNU Radio. Look in <install_dir>/share/gnuradio/examples/dtv/uhd_atsc_rx.grc

However, it requires quite a bit of cpu and it's performance is terrible unless you're close to the transmitter(s) and have high SNR signals.

How does that matter in digital transmissions? In analog, with low SNR results, you'd get fuzzy images and other similar issues. In digital broadcasts, you either receive the data stream or not. If you do, you get a signal. If not, you get nothing. I'm not an expert in TV broadcast engineering, but I'm not aware of TCP/IP "did you get that? no? here it is again" type of system as that doesn't work for realtime/live very well.

A radio baseband ASIC is much faster than a software one.

yeah, they have lots of transistors dedicated to error correction, and a core i7 does not.

Performance compared to a hardware demodulator in a television or set top box. A low SNR signal that the hardware demodulator can easily handle may not work at all with the GNU Radio software demodulator.

I think it has to do with the CPU usage of the error correction. You're right that it either works or it does not, but there is a small bit between working and not working where there is a "can be made to work if the errors can be corrected" region of the signal to noise ratio.

If there is enough CPU after decoding valid frames to error correct invalid frames, and the error correction data is intact enough, AND there is enough CPU to fix the error and decode the frame before the next frame comes in, I imagine that it would succeed. If any of those are not true, it will fail, and require more processing on the subsequent frames until a new I-frame is received.

This is half estimated guess; I don't know the nuts and bolts of how ATSC works, really.

I used TVFool in the past to setup my current antenna. This post and comment thread led me down the rabbit hole again though as one of my VHF stations has always been a bit flakey and when the wind blows UHF is an issue.

I learned about the difference between UHF and VHF and how vegetation is likely making my UHF channels bumpy when the wind howls. The VHF is likely just an aiming issue.

Anyway, one thing I’ve always looked for is a reliable way to see how changes in alignment affect the signal in real-time. I discovered Signal GH an app that will connect to your HDHomerun device and provide signal statistics.

Just thought this might be useful for anyone attempting to fine tune their setup.

Never heard of Signal GH! Thanks! I have my antenna split to my TV, and look at signal strength there, and I run TVHeadend, with HDhomerun as my source, on my Synology NAS (used to run it on my Raspberry Pi), and it provides stats and signal strength details, but all of this is on a per channel basis.

I also have Kodi on my FireTV, and it can also display stats if you use the TVHeadend plugin, and press 'o' to show live stats. Again, one channel at a time.

Edit: Just bought it. Much easier to read all the stats and far easier than lugging around a laptop when fiddling with an antenna! Thanks again.

Many of these sites are laughably wrong about the high-VHF signals. I lived on a hilltop with direct line of sight to a station on another hilltop 5 miles away. An omnidirectional antenna was worthless at pulling it in; I bought a Yagi specifically for high-VHF, aligned it to the station and that mostly worked.

Any startups working in the OTA tv space?

I can’t think of any free signal that is easily consumable as OTA HDTV.

It seems to me like one could leverage the data available nationally to discern developing trends regionally or perhaps determine metro regions that are experiencing growth or stagnation by mining the local news broadcasts or other data.

I've always used https://www.antennaweb.org/ in the past.

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