Tivax STB-T9 EPG - Page 7

Is it required that CECB convert digital captions into analog? I thought it was just the program also comes with analog caption? I kind of like the ability to have captions in translucent background. Hate it see it disabled.

Closed Captioning: A converter box is required to pass all closed captioning information included in the digital signal through to the analog TV for decoding by the TVs built-in decoder. Some CECBs also have an internal digital CC decoder, which allows for changes in font and text size.

check the thread in this forum

Evaluating Digital to Analog Converter Boxes for Users of Captioning

The EIA/CEA-909 standard is pretty limited, even clunky, at least the first version. But it allows the antenna to be smarter than the protocol.

It sends 14 bits to the antenna:
The last 7 bits are channel number
The first 2 or 4 bits can be used for direction
The 5th bit can be used for polarization
The 6th and 7th bits can be used for gain setting.
However, the use of the first 7 bits is flexible. You could use them for 128 different directions. These bits can also be used to select different fixed direction antennas. The receiver is supposed to have two modes:
one that lets you manually enter the code to be sent and one that automatically tries all 128 permutations and picks the one with the best signal strength/quality.

For mechanical rotators (or more sophisticated devices), the idea seems to be that you connect the smart antenna interface to the rotor control box which also has manual controls. You can then manually set the direction for each channel and since the smart antenna interface tells it which channel the TV is tuned to, it can remember the direction that was last used or explicitly set for that channel. Also, since it knows the frequency, it can hunt for, or track, the best signal on that frequency while you are receiving if it wants to using a duplicate tuner. A mechanical rotor would only be able to find a new peak near the current peak. It wouldn't be able to detect that the best signal is 90 degrees away from the old direction and involves a bounce of a moving van without risking dropping the signal too low.

An expensive active antenna could synthesize two directional outputs and send one to the TV while doing full sweeps on the second one using its own tuner and the smart antenna interface provided physical channel number (2-69).

There is some provision for the TV and the antenna to negotiate a more sophisticated protocol but that would require the TV to have a more intimate knowledge of the class of antenna used in order to know what to send using the new protocol, which is probably why the GE antenna only works with the GE box. In general, I would expect sophisticated devices to simply ignore anything the TV tells it to do and simply take advantage of the fact that the TV tells the antenna what the TV is doing.

Talking to an indoor antenna controller and not directly to an outdoor antenna has another advantage: the smart antenna interface was designed without the slightest consideration for lightning.

So far, however, smart antennas are only slightly less mythological than unicorns. There are only a few on the market and no rotor controllers or antenna switches with smart antenna interface that I can see.

How would you know, unless you took it apart? The box is loaded with secrets. Stuff that should have been documented. Companies don't realize that when they withhold technical documentation they hurt their customers more than their competitors. Compared to the other CECBs, this box is unusual in that the schematics are available from the FCC.

Most gadgets that come in are subjected to a ritual known as "voiding the warranty".

As for the children, if I had one of those I would just do a CAT scan. And yes, I have the data from my CAT scan here on my computer.

[quote=pixelation;13799339][quote=jimboy;13783382]
Some movies even switch formats during the show, like switching between full and letterbox.

To some extent, the box can be programmed to autodetect this. The box knows what resolution is being broadcast. If there is brightness in the center portion of the screen (i.e. not in a fade to black), the box can measure the size of the black borders. It can also compare those measurements to standard broadcast configurations and check for symetry, and do time averaging to deal with odd frames. Some things like a channel bug in the lower right corner of a 16:9 frame containing a 4:3 picture would confuse things but this could optionally be programmed around. But the box could be configured to autozoom after a few seconds to fill the screen with the maximum amount of usable image without cutting anything off. There would be an annoying jump or gradual zoom. Some content would be tricky, like a movie that has a closeup of a screen with everything totally black around it or an illuminated ball bouncing around the screen. A clear edge between black bar and content on all four sides is a pretty good indication that you don't have weird content, though a computer screen image where border fades in (room lights turned on) would be an exception. You could also have an asymmetric window detector that rapidly enlarged the "used" window when their was content outside and slowly shrank it when there was unused area. Would probably work well most of the time and you hit the zoom button when it doesn't. Might be a little sluggish restoring frame after a commercial. Some people would like it some wouldn't. Kinda like automatic transmissions.

If programs are broadcast in their native aspect ratios it is much easier.

Not really. Many, perhaps most, are based on chips that were apparently designed more or less for CECB and/or standard definition TV applications. It is hard to tell since it is hard to get data on the chips. These chips themselves may be somewhat dumbed down versions of other chips made by the manufacturer with some enhancements. The manufacturer often appears to provide a reference implementation of the software (and also the hardware) that at least illustrates basic operation of all features but may provide a limited user interface as their focus is on making a working chip. The idea may be that the manufacturer is supposed to customize and extend or even replace this user interface. Some vendors, however, may simply replace the name and logo and ship it.

The zoran Super741 chips used in the Tivax are supplied with reference software and hardware (the hardware design, however, is not merely duplicated). This includes 32MB of RAM, the leftover portion of which might store a week of program guide data (and might be intended for such). But if the reference software just had a now/next EPG, guess what you are likely to get?

The reference hardware may include extra stuff to simplify development and high quality parts to show off the chip and isn't really designed for mass production or packaging and is made in low volume at a high price per board. The box manufacturer may take that design and have a junior engineer or even a good technician half copy it, half mutilate it, leaving off what they can and replacing circuits with cheaper parts. The RS-232 port on the Tivax and similar models is probably vestigial, in that it was on the development board and may have been included on the new board design for in house testing of the prototype and then wasn't left off on the production units. It doesn't really appear that they intend to use it for field software upgrades (though they may be hedging their bets against bugs but many users won't have a computer). For in house board testing, software download, repair, etc. they could just use JTAG though the serial monitor may help for some tests. It looks like the person who redesigned the board just focused on one circuit at a time and didn't think about sharing components between circuits with results that can be comical in places.

One big difference between the chips used for CECBs and for high end tuners is the ability to output more than 480i. This lets a lot of shortcuts be taken. The chip used on the tivax supports component output and S-video but there are no connectors and amplifiers for this on the board. It doesn't support DVI. If the chip had been a QFP and not a BGA, it might have been possible to kludge together a component output but unused BGA pins tend to be buried under the chip where you can't get to them.

Tivax vs reference hardware differences:
- fewer buttons
- no SVGA
- no component/RGB output
- no ATSC baseband input
- combined tuner/modulator
They made one critical mistake and that was not putting in pads and 4 traces for an s-video connector (the amp is already there). This was probably due to confusion about whether the government allowed s-video. Then they would have been able to swap in a DTT76852 tuner module (the connected the passthru control line) or possibly an LG TDVG-H151G and an s-video connector and had a box that had all three major I/O characteristics (s-video, passtrhu, and smart antenna) in the feature matrices.

[quote=whitis;14058822][quote=pixelation;13799339]
That's a nice science project.

Instead, just use the Active Format Description system, where content is tagged with its aspect ratio and other data. The system is described in the SMPTE 2016 family of standards.

Well said!

[quote=whitis;14058822][quote=pixelation;13799339]
In fact, there is a variable for the Tivax called "BlackBarDetect". Unfortunately, it isn't doing anything.

Not nonsensical, actually. The weird stretched mode is probably anamorphic. It is intended for a 16:9 picture transmitted shrunk horizontally which is how some widescreen stuff works, including in standard def.


That sounds like a classic TV problem. Top lines leaning have to do with the phase or frequency of the horizontal oscillator or sync separator issues. If the top left corner is ok but the top right corner is wrong, your horizontal oscillator probably isn't adjusting fast enough to the 180 degree phase shift in horizontal scan caused by interlacing. If you don't see it on other boxes, it may be because they underscan. Or your sync separator is sensitive to very subtle differences between the Tivax sync signal vs. others.

There is one other possible quirk in the Tivax. The schematic looks like there are two alternate amplifiers driving the video out U6 (FMS6143) and Q7 (2N3906). Neither is listed as do not populate so if both are actually populated pulling Q7 would be a good idea. There is also a 220uF capacitor (EC35) in series with the video out line. It is possible that the charge on that capacitor is reduced during the vertical blanking interval affecting the DC offset slightly. Your sync separator should be smart enough to adjust for the DC offset, which should be but some drift could be exciting the bugs in your TV.


Maybe the Tivax is looking at the position in the PSIP terrestrial virtual channel table (TVCT) rather than the minor_channel_number stored there and the TV station is formatting the table in an unusual fashion or transmitting some audio only channels.

You may see this bug on other Zoran boxes not made by Shenzhen MTC since this sounds like it could be a bug in the reference software.


The chip naturally powers on when it gets power. Then it reads the eeprom with the settings. It would then have to intentionally power itself off. Auto power up is actually something which should be configurable: on, off, or last state, but rarely is. Not powering up is probably worse than not powering up since if you have set the autooff timer it will power itself down in 4 hours and if you have disabled autooff you probably want the unit on for something like VCR recording. Thus, in the long run it is following your instructions.


Not bizarre at all. I am surprised your remotes are that consistent. There aren't really any documented conventions for this. The Tivax is not a japanese box. I just looked at half a dozen remotes. Many had the power in the upper right, one had the upper left, a universal remote had the power button in the middle below the device buttons, and a TiVo remote had a TV power button in the upper left and the TiVo power in the upper middle. Colors varied.


This is something that should be configurable. Absent that, you would expect them to stuff 480 lines of picture data into 480 scan lines.


[/quote]
Assuming the variation in multipath was consistent when you tested the different converters, the multipath tolerance would be a function of the Zoran SoC/demodulator chip. Finding good chips when you are designing something is very hard. In some markets, such as this, it is even worse because you can't download a real datasheet. The LG chip may be better but LG still doesn't even have a web page for their chips on their miserable web site.

Receiver performance in different locations is going to depend on 1) weak signal sensitivity, 2) static multipath rejection, 3) dynamic multipath rejection, and 4) adjacent channel rejection, 5) strong signal desensitization, 6) noise burst rejection, and 7) co-channel rejection.

NTIA criteria for multipath were for static single echo only.

Where I live, there are lots of big trees.

Whitis, thanks for all in the info. The Tivax is the only box I have bought so far. It does seem to be well made. The EPG displays 4 lines of program content description (about 25 words), then truncates if the description is longer. Too bad no s-video, or alerts or search in the EPG.
Question: anyone know if the Tivax will work with the GE smart antenna (these are on the shelf at my local Target, while the GE and Venturer boxes are soldout)?
Question 2: what is the link to the schematic for the Tivax?

Somewhere in these CECB threads someone said that the GE Smart
Antenna is marketing hype and not really a "smart antenna" at all.


Dunno.

Myabe check the GE threads?


John

Thanks Johnied. There is something fishy about the GE antenna. Here are claimed features from a dealer http://www.ezdigitaltv.com/GE_Smart_..._Antenna.html:

"Automatically seeks and locks the strongest DTV signal available
Developed exclusively for use with the GE Smart Digital Converter Box
Uses sonar technology to scan your area to find the best over-the-air DTV signal without any manual adjustments "

Sonar, hmmm. And apparently it is only works with the GE box, so it isn't _that_ smart.

In any case, I don't need one - local antennas are on same hill here, and I can see their lights as I point my Silver Sensor indoor antenna. All stations come in "100%" strength, according to the Tivax. But friends and kin are not in same situation, so I'll keep an eye out for compatible smart antennas to suggest to them if they get a Tivax box.

So, you could use a "paper clip" and call it your smart antenna...

All right then. =P

John

The GE "Smart Antenna" isn't expected to be available until mid Sept:
http://www.jascoproducts.com/hdtv/GE...al-Antenna.asp
"Sonar" analogy is pretty lame....unless you're Tom Clancy, who knows that
Sonar sensor arrays do beam-forming in order to search in multiple directions....
Sorta similar to Smart Antenna beam-forming in order to search in multiple directions....

=========================
The only GE (Digital) Antenna I found on www.target.com is the Quantum:
http://www.target.com/GE-HDTV-Quantu...antenna&page=1
http://www.jascoproducts.com/hdtv/GE...l-Antennas.asp
http://www.jascoproducts.com/product...?idproduct=463
GE specs say it is an amplified antenna..."digital" means DTV compatible...
Target misunderstood "digital" to mean digital signal processor...oops....
No, it isn't compatible with EIA/CEA-909 Smart Antenna Interface Spec....

======================================
DTA-5000 remains the one-and-only available Smart Antenna.
GE (above) said they would have theirs ready by mid-Sept.
Terk said they wouldn't have theirs ready until early next year....

Last month, an RCA DTA-800 with Broadcom Smart Antenna (prototype)
were submitted to Peter Putnam for testing, but due to immediate
problems had to be returned:
http://www.hdtvexpert.com/pages_c/2TV_Converters.html

NTIA CECB test criteria DID include dynamic multipath as part of the
"Field Ensemble" requirements (item #14):
http://www.ntia.doc.gov/ntiahome/frn..._technical.htm

These are ACTUAL SIGNALS captured from fifty of the WORST locations.
Chapter 6 discusses the Field Ensemble test conditions and results for
numerous STBs and HDTVs tested in 2005:
http://www.fcc.gov/oet/info/document...on-testing.pdf
More than half weren't even close to meeting CECB (2007) requirements.

FYI: Here is link to ATSC A/74:
http://www.atsc.org/standards/practices.html

Talk to Tivax today a new batch of STB-T9 are on the way and all he would say is they have analog pass-through.

Dave

Now that the newer Tivax's have analog pass through, can someone concentrate on hacking the RS-232 port to do something really useful, like changing channels and turning the unit on and off? By doing so, you could potentially hook it up to a computer and use the computer to act as a timer. (You might even be able to control it remotely with a modem.) That would be good because reviews so far indicate the Tivax gives a better picture than the DTVPal. Also, can Tivax upgrade the old units to include analog pass through?

[quote=whitis;14066370]The chip naturally powers on when it gets power. Then it reads the eeprom with the settings. It would then have to intentionally power itself off. Auto power up is actually something which should be configurable: on, off, or last state, but rarely is. Not powering up is probably worse than not powering up since if you have set the autooff timer it will power itself down in 4 hours and if you have disabled autooff you probably want the unit on for something like VCR recording. Thus, in the long run it is following your instructions.


Actually, after a power loss, having the box always come on tuned to the last channel is better. That way, you could hook up a timer to the box and set the power to come on just before a show you want to record does. Your VCR timer could then kick in to record the show. Most shows don't last 4 hours so who cares if the box goes to standby after 4 hours.
You would only be able to record from one station when you are away. Obviously this solution is not as good as having a timer in the box that allows multiple settings, but it's better than having a VCR that's completely useless for recording when you cannot be there.

You better wait for the NTIA to add the new Tivax with analog PassThru to the list of allowed boxes before buying.

They will just it down just like they did with MicroProse.

This is probably the one thing the NTIA has been keeping their eye on.

They have kept there other eye on there other major concern for multi-dwellings like seniors in retirement homes and those who try to apply for a coupon with only a zip code and are non-eligible.

Everything else doesn't seem to matter as much to them.

Myvirtualzone is selling the Alpha Digital for "free with coupon". Shipping was reasonable too. If it weren't for the complaints about the aspect ratio, I might have bought one.

how can you tell which is which if both have the same model number

Got my Tivax box last night. Opened the box up and the board is rev D the tuner number is the same. I will try and hookup tonight and see if it has a pass-through.

Dave

Ok the box is running and no pass-through. The box runs hot about 95 deg
on my infrared Thermometer.The picture is great but my old DTC-100 hd box
looks better.

Dave

Yes, you need null modem cable. Null model is not the same as extension cable although if you are willing to sacrifice, you can just strip the cable in the middle and swap 2 wires. The trick is to find out which wire is what.

It might be easier to use DB-9 to RJ-45 converters and hack a ethernet cable to do the job.

Tonight I removered the ZR39741 chip there are no external connections from pins 9 and 10 to enable S-Video from top or bottom of the circuit board.

I may be completely wrong about this. If so, someone shout me down.

Isn't the Memorex MVCB1000 the same as the Tivax except that the Memorex has pass through?