Need Help -- Reception conundrum (either too strong or too weak!)

[deadbeef99]

My situation:

I live in a north-facing apartment in Roseville, California. I can't put up an outdoor antenna (due to apartment complex rules) and even if I could, I'm on the Wrong Side of the building. I'm about 37.5 miles from the local metro area broadcast towers (in Walnut Grove, CA) that broadcast for all of the major local stations in the greater Sacramento area.

I own TiVo RoamIO OTA (no cable card) and a TERK LOGTVAZ VHF/UHF indoor antenna, both of which have served me well for many years. (I only really care about local broadcast stations. Everything else I can get over the Internet.) I have very carefully positioned & pointed the antenna so that I get maximum signal strength for the "big five" local network affiliates that I care about. (See below.) Anything else I can pull in is just gravy.

Late last year my TiVo went south. It took me multiple months, but eventually I tracked down the problem and fixed it myself. Still, this episode convinced me that I want to move away from proprietary solutions for receiving local broadcast channels. Fortunately, a friend recently gifted me with an HDHomeRun HDHR3-US and now I just want to get it working before I purchase a new Home Theater PC to use with it so that I can run Jellyfin + K(***) to record & play back local broadcasts.

I had no problem wiring the HDHR3-US up to my TERK antenna and my local network, and then using SiliconDust's Windows-based tools to perform channel scans. Then I also used those tools (and VLC) to spot check actual reception on the local channels I care about, which are as follows:

(UHF, NBC) 3-[1,2,3] KCRA-DTx
(VHF, PBS) 6-[1,2,3] KVIE-DTx
(VHF, ABC) 10-[1,2,3,4,5,6] KXTV-DTx
(UHF, CBS) 13-[1,2,3,4,5] KOVR-DTx
(UHF, FOX) 40-[1,2,3,4] KTXL-DTx

The problem was evident immediately. Literally all channels were breaking up, even though I was getting solid green bars showing excellent reception on all of the above. Even the 40-x and 3-x channels, which are the strongest in my location, were breaking up.

I researched this problem a little and found out that, with HDHomeRuns generally, antenna amplifiers are explicitly NOT recommended. Note however that my TERK LOGTVAZ, which had been working well for me for years (with my TiVO), came with a matched amplifier. (The gain specs for this are as follows: VHF: 12 dB / UHF: 11 dB.)

Of course, once I learned that HdHomeRuns don't like antenna amplifiers I took the TERK amplifier out of the line and tried again. Now however, after a fresh new channel scan the only channels that the HDHR3-US was even seeing were just 40-[1,2,3,4]! NO GOOD! It seems that I had gone from over-amplified to under-amplified.

My thinking at this point was that maybe I need to somehow find a nice middle ground. I googled and started reading about signal attenuators. Maybe I could buy one of those, reduce the amplification from the TERK amplifier, and finally make the HDHR3-US happy(?)

Before I rushed out to do this I remembered that I had a coax antenna splitter in my closet. I grabbed this out of the closet and started looking at it to see if it might "attenuate". It's a Antronix[tm] CMC2002H-A. I didn't even have to google it to find out how much it attenuates because it says right on it (on both of the split legs) "-3.5dB".

So anyway, I put the splitter in the line between the TERK amplifier and the HDHR3-US and tried again. It didn't help. I was still getting LOTS of channels... even some that were 20 degrees off-axis and about 101 miles away at the so-called "Sutro Tower" on a high hill in San Francisco... but even for the strongest local channels the picture was still constantly breaking up, despite still getting 3 full green bars on SiliconDust's Windows tool.

So, what should I try next friends? Any suggestions? Maybe a 5dB attenuator? Any suggestions would be appreciated.

[jasonl]

We would like to get some diagnostic data to see what is happening:

1. In a web browser go to http://hdhomerun.local
   NOTE: That address will go do the first HDHomeRun device found on your network. If you have more than one HDHomeRun device, use the "device ID" printed on the bottom of the unit instead of "hdhomerun" in the address. For example, if your device ID was 104FFFFF then you would go to http://104fffff.local
2. Click "System Menu"
3. Check the "Send diagnostic information" box (if this box is already checked, please un-check then re-check it)
4. Go back one page
5. Click "Channel Lineup"
6. Click on "Detect Channels"
7. After the scan finishes, open the HDHomeRun app
8. Go into the app settings: the gear icon in the top right corner of the "Live/Recorded/Discover/Tasks" page
9. Enable the option to "Send diagnostic information"
10. Watch a problem channel for at least 10 minutes

Reply back and provide us the device ID of your HDHomeRun and we will check the logs. You can find the device ID on a label on the bottom of the HDHomeRun itself.

[deadbeef99]

Thank you for your response and for your willingness to help. Really appreciated!

Bottom line: NEVERMIND!!!

I did some more experiments/testing and I've learned that, in actual fact, there's not a darn thing wrong with my HDHR3-US as far as reception goes (with one small but important caveat, see below). Actually it's doing a fine job of pulling in (essentially) all of the major stations in my area (Sacramento), and even several low-power Sacramento stations!

The actual problem that I was experiencing, as I now know, was not that there was any problem with reception, or with the HDHR3-US, but rather, even for strong local stations, the picture (and sound?) were breaking up because I was attempting to stream live video+audio over my local (AC) WiFi. I had no idea that this would even cause an issue! I know better now!

To be clear, here is my setup:

As I said, I live in an apartment, specifically a 2-bedroom where the 2nd bedroom is my home office. This is where my file server machine, my workstation machine, and my current WiFi router (ASUS RT-ACRH18) are located. Meanwhile out in the living room I have an old, but still very functional Linksys WUMC710 media bridge which talks to the ASUS router (AC/5GHz only). Hanging off the WUMC710 (i.e. hardwired to it) I have my faithful old 2nd gen FireTV Box, my faithful old TiVo RoamioOTA, my faithful old Zotac Zbox BI320 Home Theater PC, and now, the HdHomeRun HDHR3-US.

I had been trying to view the live video+audio streams coming off the HDHR3-US from my office workstation. As previously noted, this did not go well. All of the important local channels had good signal strength, but they were nontheless basically unwatchable.

As an experiment, I disconnected my Samsung Blu-Ray from the WUMC710 bridge and plugged my laptop into the WUMC710 instead. Then I fired up the HDHomeRun Widows-tools on the laptop (in the living room) and started viewing the live stream for various local channels. Every one was 100% perfectly clear. Obviously, the variable that had been eliminated from the equation was the WiFi hop. That was obviously the real problem.

So, problem solved... mostly. But this is still perplexing and I'd like someone to explain it to me. I do know a bit about networking, and I do know quite completely about the essentially unreliable nature of UDP (and I understand that HdHomeRun output streams are sent out via UDP), however I have previously benchmarked the WiFi connection between machines in my office and machines in my living room and this WiFi hop consistently benchmarks well in excess of 400Mbps, and according to what I've read, the max bit rate for any one given ATSC 1.0 channel is (at most) 19.3Mbps. So in theory I've got at least a 20x overkill on my WiFi for streaming any given ATSC 1.0 channel. And yet this is somehow not enough to yield usable results?? Someone will need to explain that to me. (Yes, yes, I do live in a very noisy WiFi environment, even in the 5GHz band, but it still seems to me that I should be able to stream a mere 19.3Mbps without the stream becoming unwatchable due to packet loss. Am I just too much of an optimist?)

(NOTE: Just to further confirm that my attempts to stream over WiFi were really the problem I also loaded up my FireTV box with the HDHomeRun FireTV app. Remember that, as noted above, my FireTV is also hardwired to the Linksys WUMC710. Well, that also allowed me to watch any/all of numerous local channels, and reception on all of them was crystal clear. Just more proof that streaming over WiFi was the real problem all along.)

In closing I just feel compelled to say that I've decided to use my programming skills to implement a new protocol on top of UDP in order to solve this (dropped packets) problem. This new protocol will include (a) packet delivery confirmations and (b) automatic retransmission of dropped packets. I've decided to call the new protocol "Transmission Control Protocol" or just "TCP" for short. (Clever name, eh?)

But seriously, I do understand 100% why HDHomeRun boxes only stream via UDP... SiliconDust would have to add additional hardware (and costs) to each box (e.g. memory for buffering) in order to generate TCP output streams, but something like that appears to be what I need in order to actually stream live TV to my "whole house" from a low-end HDHomeRun device.

It appears that it may be possible to do real-time conversion of a UDP stream to a TCP stream via something as simple as installing a Linux tool called "socat" onto my HTPC, but I suppose that in the end that will be unnecessary if I just install TVHeadEnd on my HTPC. I'll know soon enough because I will most certainly be doing that in the very near future.

One last note about reception... As noted above, I'm getting most, but not quite all of my local channels... even low-power ones... with crystal clarity via the HDHR3-US. The one exception is the local PBS affiliate, KVIE aka logical channels 6-{1,2,3,4}. Sadly, the HDHR3-US doesn't even ]see these channels on a channel scan at all! This is really rather disheartening because (a) I'm a big PBS fan and (b) when connected to the very same antenna, both my 2017 vintage TiVo and my even older HDTV's receiver do see these channels... not well, but just barely enough to be watchable, at least when it's neither rainy nor windy.

I really don't understand this and hope someone from SiliconDust can explain. I read somewhere that reception can be problematic for the lower half (2-7) of the VHF band, but google is telling me that the two remaining major VHF stations in my area (KVIE/PBS and KXTV/ABC) are in fact mapped to physical channels 9 and 10, respectively, so I'm perplexed. Also perplexing is that fact that these two stations have transmission towers in virtually the same location (Walnut Grove, CA) and have very similar power (33kW versus 28.6kW, respectively) and yet I'm receiving all KXTV subchannels with crystal clarity via my HDHR3-US while that same HDHR3-US with the exact same antenna doesn't even see any of the KVIE subchannels on its channel scan. So as Seinfeld would say "What's up with that?"

[rikd]

So, problem solved... mostly. But this is still perplexing and I'd like someone to explain it to me. I do know a bit about networking, and I do know quite completely about the essentially unreliable nature of UDP (and I understand that HdHomeRun output streams are sent out via UDP), however I have previously benchmarked the WiFi connection between machines in my office and machines in my living room and this WiFi hop consistently benchmarks well in excess of 400Mbps, and according to what I've read, the max bit rate for any one given ATSC 1.0 channel is (at most) 19.3Mbps. So in theory I've got at least a 20x overkill on my WiFi for streaming any given ATSC 1.0 channel. And yet this is somehow not enough to yield usable results?? Someone will need to explain that to me. (Yes, yes, I do live in a very noisy WiFi environment, even in the 5GHz band, but it still seems to me that I should be able to stream a mere 19.3Mbps without the stream becoming unwatchable due to packet loss. Am I just too much of an optimist?)

There's a very big difference from data transfer to real time AV Streaming.
Live TV comes in at X bitrate and the HDHomeRun buffers up enough to send a packet, and repeats every couple of milliseconds.
Those packets are sent to the linksys over wire and then the asus via wifi and then to the laptop over the wifi again. If the packet cannot get an available slot (due to many possible issues) then it will get dropped, or if something happens and the noise on the RF suddenly goes off the charts for a brief period and corrupts it - packet lost.
So the most important thing for live streaming is the ability to transmit a packet at a sustained time interval.. not lots of packets in a burst.
Wifi just doesn't like that - but adding more slots (e.g. 5GHz with bigger bandwidth), media prioritisation, and utilising features like modifying broadcast to unicast will help ensure availablity of slots for the packet to be sent and not dropped.

But seriously, I do understand 100% why HDHomeRun boxes only stream via UDP... SiliconDust would have to add additional hardware (and costs) to each box (e.g. memory for buffering) in order to generate TCP output streams, but something like that appears to be what I need in order to actually stream live TV to my "whole house" from a low-end HDHomeRun device.

TCP won't help.
TCP just adds some overhead to retransmit the packet if not received by the consumer hoping that a retry (one of many) will result in the packet getting through.
So.. packet loss will continue, but now you have the overhead of the sender setting a timeout waiting for a client to ACK that it received the packet, otherwise it retries the same thing again up to X (usually 3) times. In the meantime the HDHomeRun keeps sending out new UDP packets which the client might receive and when this 'bad' packet finally gets through it will be discarded since it's old and out of date.

Overall - suggest you look to why your Linksys to Asus is dropping the packets. Some hints in the first part of the response to go look at, but also look at the other devices you have connected to the bridge - fwiw, in my experience Amazon devices are noisy (very very noisy).

[deadbeef99]

Thank you. I will experiment with powering off the FireTV box entirely and then repeat my streaming-over-WiFi test and I'll report back my results.

Separately, I would very much like to be instructed on how, exactly, I would "modify broadcast to unicast" in this situation/setup. I really have no idea how to do that.

(I should perhaps note also that I did look into the topic of QoS and I did insure that both my ASUS WiFi router and my Linksys Media Bridge have that "enabled", but I gather that there are a whole bunch of more obscure settings relating to QoS that I might... if I was smarter... be able to tweak in order to give the stream from the HDHomeRun box highest priority, but I could probably use some guidance about that also.)

Lastly, you didn't answer my question about my local PBS affiliate, KVIE (logical channels 6-{1,2,3,4}, physical channel 9). Why is that one never showing up after a channel scan? Is there a way to force it to be included in my channels list, even though it is not seen in the channel scan?

[NedS]

I really don't understand this and hope someone from SiliconDust can explain. I read somewhere that reception can be problematic for the lower half (2-7) of the VHF band, but google is telling me that the two remaining major VHF stations in my area (KVIE/PBS and KXTV/ABC) are in fact mapped to physical channels 9 and 10, respectively, so I'm perplexed. Also perplexing is that fact that these two stations have transmission towers in virtually the same location (Walnut Grove, CA) and have very similar power (33kW versus 28.6kW, respectively) and yet I'm receiving all KXTV subchannels with crystal clarity via my HDHR3-US while that same HDHR3-US with the exact same antenna doesn't even see any of the KVIE subchannels on its channel scan. So as Seinfeld would say "What's up with that?"

Just a little background: In theory VHF is actually "easier" to receive, but most people don't have a proper VHF antenna, which requires long elements, especially for VHF-lo. These days most people have a little UHF antenna, so VHF is seem as less desirable by broadcasters.

As for why KVIE isn't showing up for you, we'll need to look at some diagnostic information to get a better understanding about what might be happening. For the older DUAL models the debug steps are a little different than what was given before:

1. If you have not already done so, please install the latest HDHomeRun Software for Windows from http://download.silicondust.com/hdhomer ... indows.exe (NOTE: this is a separate download from the Windows 10 app available in the Microsoft store)
2. Run HDHomeRun Setup, enable “Send diagnostic information...” on the Advanced tab and click Apply. If you do not have an Advanced tab, close HDHomeRun Setup and reopen it.
3. Unplug the power from the HDHomeRun and plug it back in
4. After the power-up sequence finishes, click “Scan” at the top of the CableCARD or Digital Antenna tab and close the utility when finished

Reply back when done with your "Device ID" and we can take a more detailed look.

[Billi23]

Also perplexing is that fact that these two stations have transmission towers in virtually the same location (Walnut Grove, CA) and have very similar power (33kW versus 28.6kW, respectively) and yet I'm receiving all KXTV subchannels with crystal clarity via my HDHR3-US while that same HDHR3-US with the exact same antenna doesn't even see any of the KVIE subchannels on its channel scan. So as Seinfeld would say "What's up with that?"

You're most likely picking up KXTV/ABC from Sacramento on RF channel UHF 36.
https://www.rabbitears.info/contour.php ... te=2&map=Y