Best ATSC/ClearQAM Tuner for Win7MC

[adam1991]

I should have done more research before buying two Hauppauge HVR-2250s. I thought they were a good deal after reading the reviews - two analog tuners, two ATSC tuners, two ClearQAM tuners, able to record ClearQAM and ATSC at the same time, etc.

BTW, any given tuner in the 2250 can tune only one thing at a time. Any given tuner CANNOT "record clear QAM and ATSC at the same time."

The 2250 itself, because it has two tuners, can "record clear QAM and ATSC at the same time;" that's because one tuner is recording QAM and the other is recording ATSC. It's handy to have multiple tuners in one slot, and the 2250 provides that, but don't think that it'll record multiple streams per tuner.

One stream per tuner.

Now the question: Is there a tunner that will allow HD reception for ATSC and ClearQAM via cable?

One stream per tuner, no matter what you have.

[richard1980]

8VSB is just a modulation scheme. There's no reason why somebody couldn't use 8VSB modulation over a cable line. The thing is, here in the US we don't do that because 8VSB modulation isn't as efficient as QAM. 8VSB can only push 19.39 Mbps of data through 6 MHz of bandwidth, whereas 64QAM can push 27 Mbps through the same 6 MHz bandwidth and 256QAM can push 38.8 Mbps through the same 6 MHz bandwidth. The FCC mandated that OTA broadcasters use 8VSB modulation, but they never told the cable companies what to do. Instead, the cable companies have voluntarily followed the standards published by the Society of Cable Telecommunications Engineers (SCTE), which require either 64QAM or 256QAM modulation. The reason cable companies voluntarily do this is because QAM can deliver more data with the same bandwidth than VSB, and cable companies here in the US are looking to push as much data as they can through their pipeline. But there's absolutely nothing except for common sense preventing any cable company from pushing an inefficient 8VSB signal through their lines. The same thing applies in South Korea (minus the FCC part). The cable company in question could very well be pushing 8VSB through the cable line. It just saves them from having to demodulate and re-modulate the signal.

With that said, what CEHKIA said about the channel range is correct in a way. OTA channels here in the US (the ones we refer to as "ATSC channels") are only allowed to use a specific frequency range for broadcasting (it's the same as the old NTSC frequency range, but a smaller range because the FCC auctioned off some of the frequencies for other things). Cable companies don't have that same frequency block restriction and can broadcast outside of the OTA frequency range. It's possible the 2250's 8VSB demodulator only works for the OTA ATSC frequencies, but any frequencies outside of the OTA frequency block are expected to be QAM modulated. To put it simply, the 2250 might expect channels 1-10 to be either VSB or QAM, but anything above channel 10 it thinks will always be QAM. If an 8VSB signal is broadcast on channel 11, the tuner may try to demodulate it using a QAM demodulator instead of an 8VSB demodulator, which would fail to work properly.

[CEHKIA]

Adam1991: As I have stated both the Sony TVs and the Pinnacle PCTV card stated that the HD channels I've been trying to get are located outside the ATSC channel range (Channels 2 (57 MHz) - 69 (803 MHz)). The channels are identified as channels 79 (555 MHz), 80 (561 MHz), 81 (567 MHz), 82 (573 MHz), and 83 (579 MHz) which are in the QAM range. The Sony TV states that the modulation is 8VSB. I'm only reporting what is presented to me. Remember, this is South Korea and they don't always follow the standard.

[richard1980]

You are confusing terms again. There is no such thing as "the QAM range". QAM and VSB are modulation schemes and have nothing to do with the channel number or frequency range a specific channel uses. Plus, since the channels are using 8VSB modulation, you should know that they aren't in "the QAM range". If there was a "QAM range", the channels would be modulated using QAM, not 8VSB.

Now I think I have figured out the problem and the clue is the channel numbers and frequencies you posted. The frequencies you posted are the QAM carrier frequencies for those channel numbers, which can't be right if the channels are modulated using 8VSB. VSB and QAM use different carrier frequencies schemes, with VSB carrier frequencies ending in .31 and QAM carrier frequencies ending in either .25 or .00. Not only do VSB and QAM use different carrier frequencies, but cable and OTA systems use different frequency bands for each channel number. For example, OTA channel 30 uses 566-572 MHz, but channel 30 over cable uses frequencies around 260 MHz. Now in this case, there are two problems. First, OTA channel 79 isn't in use in either the US or South Korea. The frequency required for OTA channel 79 starts at 860 MHz, which is in a frequency range that is used for mobile radios and cell phones (it's been that way since 1982). So you can safely rule out the possiblity of your coax line acting as an OTA antenna. Additionally, 860 MHz is approximately the same frequency that cable channel 135 is broadcast on, and that is the upper limit of many of the available ClearQAM tuners (some don't even go that high). Yes, there are some tuners that can go higher, but for the most part, ClearQAM tuning capabilities start tapering off at about channel 125, which also corresponds to OTA channel 69, the highest OTA channel number available.

Here are the specs from the Hauppauge website: "Dual 125 channel cable ready TV tuners". I don't have one, so I don't know exactly how high the frequency range goes, but according to Hauppauge, it's channel 126.

So here's my theory: One of two things is happening. Either those channels are actually being broadcast on the frequencies above 860 MHz, in which case you are trying to exceed the limitations of the tuner, or, the channels are actually being broadcast in the 550-580 MHz range and for whatever reason, the 2250 thinks it needs to go to frequencies above 860 MHz to tune those channels, which still exceeds the limitations of the tuner. If that's the case, I'm betting the tuner is getting confused about the modulation scheme, thinking that 8VSB only applies to OTA frequencies (since here in the US that would be true). Without being able to pinpoint exactly what frequencies need to be tuned, it's impossible to say which is the correct answer.