Digital Tuner problems

Some people have mentioned that the Tablo will not pick up a signal even though it appears to be strong but televisions show that channel. A conclusion is that the Tablo tuner isn’t that strong. One sees this complaint with other DVRs constantly - TV tuners outperform them.

However it is possible that the Tablo tuner is strong but that another factor is at play. I noticed the other day that my televisions were picking up three channels that my PC based tuners were struggling with. This despite that my PC tuners were newer with better chipsets than any of my television tuners. I couldn’t figure this out until I noticed that the error rates showing on PC signal monitors were quite high. It appears that the televisions couldn’t care less about these error rates and went on happily displaying the channels. The PC tuners on the other hand appeared to be trying to handle the error rates with some sort of correction algorithms and failing. The dumb TVs couldn’t care less about “correcting” the signals and just shoved them through.

The PC tuners being “more intelligent” probably were trying too hard to “correct” the signal errors and screwing up. I’m guessing that tuners inside digital boxes “try too much” error correction because of a box’s smarts and fail to JUST pick up and convey the channel whereas the dumb ole TV just passes a channel through errors or not. It may be advisable for digital box designers to just allow a signal to get through and forget the “error handling” stuff.

Sometimes dumb beats smart. BTW I’ve noticed this problem for the past several years where television tuners continuously outperform ANY DVR tuners even though both get their chipsets from the same manufacturers…

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In thinking about the fact that tuners inside digital boxes tend to underperform televisions, there may be other factors involved. Such as the basic fact that the tuner sits inside a digital processing box as opposed to sitting inside a television. To give an example: my Samsung TV tuner outperforms my Samsung ATSC STB tuner even though both come from the same manufacturer and use the same chipset. Something about the overall architecture of a digital box tends to detract from a tuner’s performance…

Neither of my PC tuners have internal splitters (nor does my Samsung STB) so a split signal (weakened) cannot be blamed for worse performance by a tuner within a digital processor.

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I’ve noticed that as well. My antenna comes in through a splitter, which feeds 3 TV sets as well as the Tablo. Signal strength is showing pretty strong on my TV sets, and channels come in beautifully with no dropouts. I happened to notice that Tablo was missing one of the sub channels in the scan… i.e., I was getting 8.1 & 8.3, but Tablo was missing 8.2, so at the suggestion of support, I removed the splitter and fed the antenna directly in to Tablo, did a scan, and my missing channel was found and came in beautifully. So, I reconnected the splitter and TV sets, and put the Tablo off the splitter again. My missing channel 8.2 was still there, and was coming in beautifully with no dropouts or pixelization. I suggested to Tablo that they may have an issue with their detection algorithm, given my results. There’s no reason that Tablo should be rejecting that channel on its scan, given its signal strength, and ultimately, the performance of the channel. Needless to say, I didn’;t do a Tablo rescan after putting everything back in place, and I’m able to enjoy my missing channel now.

I’ve had the same experience where my TVs pick up a channel that my digital processing boxes don’t. It’s as if some signal processing algorithm inside the digital box is failing based on the flimsiest excuse (a certain error rate on that channel that can be ignored?). There is something about a digital box that makes a tuner underperform a TV. I remember ten years ago when Tivos came out that people had the same complaint, “My TV picks up channels that my DVR doesn’t” or “My TV’s signal strength for a channel is better than the DVR’s.” I’m not sure its the tuner itself because the same pattern has been there for a decade independent of manufacturer. Something in the design of any digital STB\DVR…

I’ve had to enhance my antennas not for my TVs but for my DVRs. That’s why I always run two lines from the antennas - one to the TV and one to the DVR. The DVR is used for recording; the TV for watching live OTA TV and cruising channels.

There is a 4 way splitter in the Tablo, which may or may not explain your results.

One of Tablo’s support people stated on another thread that the tuner’s splitter is amplified to negate any signal loss. That said, my TVs come off a 4-way splitter and they beat any DVR for signal reception.

I’m not sure a tuner or a splitter is the issue why any digital box underperforms a TV for signal reception. That used to be a standard complaint and yet the tuners are of good quality. My take on this is that it is the overall architecture of a digital box and NOT the tuner that contributes somehow to a DVR underperforming a TV when it comes to signal reception. My LG LED TV beats any and every DVR hands down for signal detection and channel reception (and yes I know that LG makes great tuner chipsets that quite a few other TV manufacturers use themselves). Which is why I bought an LG because of its OTA prowess.

It does not matter if the Tablo amplifies the signal before splitting it 2 or 4 times (depending on the model). The signal is already degraded from the 3-way split. Think of a radio station with static. No matter how much you turn up the volume it’s still static. You should use a distribution amp instead of a splitter. Also if you have any other splitters along your run you should terminate any unused ports.

The issue I’ve presented in this thread from the beginning is that digital boxes of any kind will for some reason always lag behind televisions when it comes to reception. For some reason this has been the case since Tivos and DVRs first came out. Under any circumstances and in any situations TVs seem to beat any DVRs when it comes to signal detection and reception regardless of splitters or amplifiers. My Samsung and LG TVs have always beaten every single DVR (and I’ve had 6 different DVRs from different manufacturers over the past ten years) under the same conditions and in the same environments. And I don’t think it is the quality of the tuner or signal splitting but something else associated with DIGITAL processing of signals. That is the mystery to me…

This is not a rant against DVRs (I have several including the Tablo which I enjoy). Only to state that a DVR will always underperform a TV when it comes to signal reception and one had to be aware of this fact when getting a DVR. I compensate for this by stacking two ChannelMaster 4228 antennas (16 bays) to ensure a good, stable signal to all my devices.


This is certainly plausible. As noted above, the Tablo does use an amplified 4-way splitter. This mitigates the loss from a split, but (however small) there is still a loss in comparison to a TV using a single tuner.

If there’s a particular channel on the ‘edge’ of the ‘tunable cliff’ there are certain cases in which the Tablo may not be able to detect a channel while a TV can. Digital signals usually function in an “on or off” pattern rather than seeing slow degradation of the stream - like on analogue.

To further mitigate any differences like this, we usually recommend a few (relatively easily implemented) changes to the setup:

  • Make sure the antenna is as high up as possible.
  • Try to avoid splitting the coaxial connection - there is a DB loss to the signal when you split the connection.
  • Reference to ensure that your antenna is pointed in correct direction.
  • Shorten your coaxial cable; the longer the cable, the more lossy the connection will become.
  • Conduct frequent channel scans to test your changes (Settings > Edit channel lineup > Rescan).

Hope this helps, all.

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What’s perplexing to me is that Tablo missed a subchannel in my case. As I understand it, all the subchannels are broadcast on the same channel stream, and are multiplexed onto a single carrier. That means they come from the same location, on the same broadcast antenna, on the same carrier frequency and at the same power level. Now what’s really strange is that when I bypass my splitter and run my antenna directly to the Tablo, the missing subchannel appears, along with all other subchannels that I previously had.

It’s possible that the received power level of mystery channel stream is marginal (as seen by the Tablo’s tuner), and is fading in and out, but 2 successive channel scans of the Tablo yielded identical subchannels detected when coming off my splitter. Now, to really be a valid test to prove that theory, I’d have to do channel scans numerous times and compare results, and perhaps I’d see a different mix of subchannels being detected or not over time. Maybe in my spare time…


What if someone wants to run a line to a Tablo in Room1 from an antenna and also another line to another room (Room2) where he wants to connect that line directly to a TV (there are no devices such as a Roku in Room2)? This is what I do.

My setup is a stack of 4228 antennas, a good pre-amp (0.85 db noise) which amplifies the signal by 36 db, and then a two-way split (a good quality GE $10 splitter). My Tablo BTW does report 5 green dots on all channels so I don’t have a problem. HOWEVER my LG TV shows one more channel than does the Tablo (albeit a minor unimportant channel). Both TV and DVR are fed by the same two powerful antennas and a great pre-amp. I don’t mind the missing channel (which is minor for me) because everything else comes in at a rock solid 100% but this does demonstrate what I have been discussing. This BTW is not unique to Tablo - a Tivo I have shows the same issue! As does the Hauppauge PC tuner I have. The TV outperforms (for some strange reason) all of my digital processing boxes…

BTW The Hauppauge tuner is a single tuner in my PC and it is outperformed by my LG TV (both being single tuners); this is why I started considering that it is in the nature of a digital processor that makes a tuner lag behind that of a TV.

I think that you will find that your TV is provided a much better ground then any of those other boxes which gives the TV a leg up in the RF handling department.

You may be right which is why I suspect that it is the things around a tuner that “influence” it in its RF handling and that somehow a TV’s internal environment is responsible for it’s better RF handling. In the past it was always the tuner chipset which was questioned inside a box and not what elements the box was composed of.

As far as splitting a signal, there are two aspects to a signal - its raw electromagnetic strength and its signal-to-noise ratio (SNR). I can split the signal coming from my stack of antennas 4 ways diminishing the “strength” yet preserving the SNR such that each leg of the split still reports a high SNR (quality). A two way split is hardly noticable to my TVs especially with a pre-amp that has less than 1 db noise.

I also have wondered if various brands of external USB drives are more “noisy” than others… eg. if some either leak RF over the usb cable or ambient locally short range transmitted RF thats interfering with the channel reception for stations that are already marginal …

Interesting thought! Digital processing boxes such as DVRs and PCs have so many active components in them that sit close to a tuner and share the system bus.

I once worked at a manufacturing company that had circuit boards within PCs “laminated” with special spray for security reasons because some of them were radiating data that could be picked up by scanners.

You keep calling them " Digital processing boxes" what exactly makes you think that your TV isn’t doing the exact same digital processing perhaps even with the same chipset at the Tablo ?

Grounding maybe a part of your issue. Do you have a solid ground at the splitter ? Mine is grounded with #10 wire straight to the house ground at the water meter and my mast is #6 wire to the same location. My Tablo picked up everything both of my TV’s did with ease

Mine used to pick up most channels now it will not pick up any channels. I reset my Tablo and I can’t get any channels to do the set up.

Can you unplug the antenna cable from the Tablo into a tv and pick up the stations? If not, then it is an antenna or cable problem. If the TV picks up the stations and the Tablo does not, then you should call Tablo Support.

@Kimberly Try rebooting the Tablo (tap the blue reset button once, don’t hold it down) then run a new channel scan. If this doesn’t take care of the problem, send us a ticket. We’ll work with you to get this fixed.

My TV picks up all the stations in my area. The tablo picks up 0. I have talked to support, and they keep saying it is my antenna. I tried 4 different antennas and the tablo is still picking up 0 channels. I think my tuner on my tablo is messed up.