: ATSC Tuners In HDTVs (see Samsung Poll)
2006-12-02, 11:44 AM
This screen gives me information about the signal's strength/quality, signal to noise information, and an AGC value, given as a percent number .
I'm assuming that this value represent the Automatic Gain Control level in use.
This is most likely the case. For those who don't know, AGC is a circuit that will adjust the amount of amplification (or attenuation) based on the signal strength. This way strong signals can be left alone (or possibly even attenuated) while weak signals can be amplifed in an attempt to put the signal within a desired range. Now this is only half the battle as you also need to have a good Signal to Noise Ratio (SNR).
Now... How should I interpret this AGC value?
There are several ways to use this information. One is to look at it when adjusting your antenna as you are wanting to keep this percentage as low as possible. Another is if all stations have a high percentage (especially 100%) and your antenna is already adjusted it can be an indication that you could benifit from an external amplifier.
For me, this value is within only a couple of percent the same on all channels, and normally lies slightly below 20%.
Does that mean that the incoming signal's amplitude needs to be reduced to about 1/5th of its incoming strength in order to be processed?
Not necessarily. The circuit may be adjusting either the amount of amplification or attenuation (or both). To figure out what it is doing in actuality you would probably have to talk to Sony.
Is it true that the AGC value gives information about the signal's amplitude, while the signal to noise ration gives information about a signal's purity or cleanliness?
Yes. See above.
If this is true, then am I right in thinking that pre/distribution amplifiers should have an impact on the AGC value shown?
Yes. Pre and Distribution amplifiers will affect the AGC. They will also add noise and thus affect your SNR.
2006-12-10, 12:17 AM
Read through the thread and didnt see anything about having an on screen TV guide with built in tuners. Do built in tuners offer the guide that you seem to get on the STBs? Is it manufacturer (the TV) dependent?
If they do have the guide built in, is there any noticeable difference (in terms of what features are available) between a built in ATSC tuner and an STB?
2006-12-10, 03:43 PM
I think a Guide feature is pretty standard whether an ATSC tuner is built-in or an STB. See this thread for a user's experience:
If anyone can confirm/correct whether the Guide feature is universal to ATSC tuners please let us know.
2006-12-10, 05:03 PM
Well, my Sony 32" XBR has a guide button on the remote, but it's not the guide you'd think it'd be (wrt an ATSC program guide), it just lists 6 channels ahead of the current channel, not what will be playing on the current channel in the future. As far as I know, my Sony HDTV doesn't have a ATSC program guide.
My HDTV Wonder is a bit different. It allows to see what's coming up next, but that's it. Better than nothing, I suppose.
2006-12-10, 09:16 PM
The Guide button on my Hitachi f59 doesn't offer any guide info related to it's internal ATSC/NTSC tuners.
The owner's manual states that this feature is for use when in the CBL or SAT/STB mode. Pressing the button accesses the Channel Guide of other devices.
This is pretty poor when compared to Jake's 37" lcd tv. (see stampeder's link)
The Info button does offer some program info depending, of course, on the broadcaster's PSIP. Basic info is; channel #, picture source, audio info, time, title, synopsis etc. No schedule whatsoever.
Signal strength is accessed through the Menu, Channel Manager, Signal Meter. The meter reading for whichever channel you were on is now diplayed. There is a bar that fluctuates 0-100 and a 'Peak' reading which shows where the strength was at it's maximum.
This must seem very uninteresting most readers. It does, however, illustrate what I see as a shortcoming with the "Built Into" aspect of an atsc tuner.
All this scrolling around through menus cannot compete with a dedicated ATSC STB like the Humax.
Limited comparisons of the tuning abilities of Hitachi vs. Humax shows the Humax slightly better. The Humax tuned some weaker signals that the Hitachi missed.
Although I favour my Humax tuner, I must say that I'm happy to have an internal atsc tuner in my Hitachi. The tuner was included in the cost whereas the Humax was $300 CDN delivered.
2007-01-04, 11:14 AM
I purchased the Sharp 37D40U on the weekend and am just now trying to find some OTA HD. The problem is that the 'Antenna Setup - Digital' is greyed-out in the setup. I currently have a coax from my tower plugged into the TV.
I have tried unplugging the TV but still no luck.
Any ideas are appreciated.
2007-01-09, 02:01 AM
Congrats on the nice tv. I just picked this one up too! The "Antenna Setup - Digital" menu only "lights" up when you are on a digital channel. From this menu, it will allow you to view signal strength and channel strength.
If you have already performed a channel search for both AIR analog & Digital channels, and it has found some, all you need to do is start channel surfing until you find a digital channel. For example, my tv has found channel 4.1 CBC HD.
While changing the channel, the TV reports whether the current channel is analog or digital in a little blue box in the upper right hand corner with the channel number.
2007-01-09, 10:03 AM
Thanks Soccer! I finally did get to the antenna setup screen. I just rescanned for digital and analogue channels.
2007-01-13, 02:17 PM
I have seen references to this but am unable to determine the answer conclusively or find an existing thread discussing this.
Are the OTA HDTV broadcasters including a programming guide with their signal? I saw somebody refer to having pulled in a 24 hour schedule from CBC-HD.
If so is there a trick to displaying it? I have tried the 'GUIDE' button on the remote for my Toshiba 50HM66 DLP and don't see any results. Can't seem to find much in the way of instruction on that either.
In any case, if this isn't an option, what is the best TV guide for Toronto/Buffalo OTA HDTV?
2007-01-13, 05:05 PM
See the Knowledge Base & FAQ posts about PSIP Data to understand how the EPG works.
I don't know what the deal is with your Toshiba's ATSC tuner but is there a 1-800 number you could call for assistance from them? If there is no EPG in those Toshiba sets you might want to consider a product return for a model/brand that does it properly.
2007-01-13, 05:10 PM
I believe Toshiba uses TVGOS from gemstar and not guide info from ASTC OTA.IF its TVGOS then the guide info comes from CFTO analog or WNED analog over several nights.I also believe Rogers cable may strip out the data.There is a thread about it with Toshiba DVD recorders.IF your Tv supports ASTC tv guide system then each OTA digital stations sents its own channel info.Cfto-dt is the only station with no info being provided for ASTC guide info.BE sure not to delete the analog stations if you are using TVGOS.
2007-01-14, 04:42 AM
It looks like it might be a feature that becomes accessible on the slightly more expensive model (50HM96 vs my 50HM66). Not sure I'd give up the discount I got by returning the set over this feature, even though it would be nice to have.
2007-01-14, 10:11 AM
I have a atsc build in my Panasonic 42pd60 a EDTV and even if my tv is not HD,I can get all the OTA HD channels and the quality is amazing(even if it displays in 480p).The only thing I dont have is a guide option for the OTA.....but hey paying less than 1500$ for that TV I knew what Id have
2007-02-10, 03:08 PM
In hopes of getting CBC-HD for the hockey games, I went out to London Drugs and picked up a Terk antenna. I plugged it in, switched the TV to DTV mode, and did a channel scan. To my surprise I picked up KCPQ/FOX right away, and a couple of other cartoon channels with a bit of antenna moving. I turned the antenna to another direction, did another channel scan, and CBC HD appeared! So far I am pleased, except for the fact that there is NO SOUND on any of these channels! The way I understand digital TV is you either get nothing or everything, so I'm a bit puzzled why there is no sound. Am I missing something? The sound is fine on the analog cable channels.
Another thing, in the OTA forum there are references to "getting 80% signal" and stuff like that when adjusting the antenna. Is there a mode on this TV that I can use to fine tune the antenna position? It would be nice to get immediate feedback as to what the signal strength is as I move the antenna.
Thanks for any help!
2007-02-10, 03:17 PM
Hi Martin, its very weird that there is no sound on the DTV stations but sound on the analogues. I'm guessing its a setting on your Acer TV, such as all digital sound needing to be switched between internal speakers and external Toslink/SPDIF port.
I recommend that you go into the OTA Forum Reception Results sub-forum and post about your general reception in the appropriate thread for North Vancouver, but we'll continue to deal with the specific Acer TV DTV issues in this one.
2007-02-10, 03:55 PM
Thanks for the reply Stampeder. It is indeed a setting on the TV. After finding a post about a hidden menu on the TV, I fiddled around for it a bit and the sound came on, but now it forgets the brightness when I switch out of DTV mode. I'll follow up in one of the AT3705 threads.
2007-02-15, 10:29 PM
I have an Toshiba 32HL66, and the tuner is great except the audio is never lined up. I tried to exchange for another one at future shop, but the guy blamed it on my antenna/cables and said that the audio was off because of multipath.
I have my antenna aimed at Toronto, so Buffalo is coming in from the side, but all the channels are still strong from Buffalo, mid 80's usually. The sound isn't going to be off because my antenna isn't aimed at Buffalo is it? I shouldn't have to aim the antenna directly at Buffalo to get the audio in sync. As far as I was aware, you either get the channel or you don't, i don't see how it could be the antenna/cables i'm using.
2007-02-15, 10:50 PM
Multipath will not cause ATSC audio to be out of sync with the picture. I think he just made that up! ;)
2007-02-16, 01:31 AM
of course he did.
What a great way to convince the consumer to forget OTA and get a Rogers STB.
2007-02-16, 10:09 AM
so then that tuner in the TV, is it broken? Would Toshiba sell a TV like that all across US and Canada with an ATSC that doesn't line up the audio it receives?