posted January 18, 2003
Guys,
Just for your info, the Panasonic STBs are still the best STBs that we have seen. For example, the Samsung SIRT-165 clips everthing above ~90IRE to white (I'm using the technically incorrect IRE for ease of explanation). The JVC D-VHS deck clips everything below 0mv.
The "50" has an input window of 15db and this is one reason it is tougher to tune in stations. In the "51" they increased the input window to 30db.
Moral of the story, hold on to your Panasonics.
Jimdoo
Panasonic: TUDST50/51
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Hi Wayne and Richard,
The input window can vary from STB to STB. Joe Kanes 50 has a window of -25db to -10db. His 51 has a window of -25db to +5 db. Here is how to test yours:
www.videoessentials.com/jkp_resources.htm#DTV
We have found that they do not like heat and good ventilation can help with performance. If you have signal strength issues, you can try a simple attenuator or an amplifier.
I have one 50 and 2 51s that I haven't tested, but they both work equally well. I'm roughly 3 or 4 miles from the Boston transmitters but in the shadow of a large hill. I'm still using the $20.00 dollar Radio Shack UHF/VHF antenna (Burns is sending me a better one soon!!!as of 09/00!!).
There is a menu in the JVC deck where I had to enable the 1394 for a pass thru situation. However, the JVC deck will not pass BTB information and the component video outputs on the 50 and 51 will. If you are trying to record from the Panasonic STB to the JVC, it isn't always simple. If you power up both units simultaneously they sometimes will talk to each other and permit the recording, sometimes not.
Jimdoo
The input window can vary from STB to STB. Joe Kanes 50 has a window of -25db to -10db. His 51 has a window of -25db to +5 db. Here is how to test yours:
www.videoessentials.com/jkp_resources.htm#DTV
We have found that they do not like heat and good ventilation can help with performance. If you have signal strength issues, you can try a simple attenuator or an amplifier.
I have one 50 and 2 51s that I haven't tested, but they both work equally well. I'm roughly 3 or 4 miles from the Boston transmitters but in the shadow of a large hill. I'm still using the $20.00 dollar Radio Shack UHF/VHF antenna (Burns is sending me a better one soon!!!as of 09/00!!).
There is a menu in the JVC deck where I had to enable the 1394 for a pass thru situation. However, the JVC deck will not pass BTB information and the component video outputs on the 50 and 51 will. If you are trying to record from the Panasonic STB to the JVC, it isn't always simple. If you power up both units simultaneously they sometimes will talk to each other and permit the recording, sometimes not.
Jimdoo
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I am not quite sure what a "window means" in terms of reception.
Example:
Highest is + 6.9
Lowest is -15.3
So I have a 22.1db window - OK.
The tuner only recognizes 10 (-15.3) and 19 (-3.9) but refuses 27 (-2.7) which is within the window. The other four are over 0 db so they are outside the window which I suppose means the tuner is refusing them due to the window. but...
How does the receiver determine where the window begins and ends? Are you saying that by removing channel 10 from memory I will get the other channels because they have a window of 10.8db?
Hmmm.
Richard Fisher
Example:
Highest is + 6.9
Lowest is -15.3
So I have a 22.1db window - OK.
The tuner only recognizes 10 (-15.3) and 19 (-3.9) but refuses 27 (-2.7) which is within the window. The other four are over 0 db so they are outside the window which I suppose means the tuner is refusing them due to the window. but...
How does the receiver determine where the window begins and ends? Are you saying that by removing channel 10 from memory I will get the other channels because they have a window of 10.8db?
Hmmm.
Richard Fisher
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More tidbits
The input window doesn't shift. It will tune stations that have a good signal with little to no multipath that are very close to or within the input window (in the case of Richard's 50, that input window is most likely similar to the other 50s window of -25db to -10db). The Joe Kane article has a schematic that shows how to monitor a signal level. With a known level you can either attenuate or amplify a signal to within the input window, however, if strong multipath is present these 1st generation tuners may still have trouble tuning in the signal. Going by the data Richard has provided, I would attenuate the -15db signal down to -18db, then do a new auto scan, if the STB still can't tune the hotter signals, try attenuating to -20db and run auto tune again, and so on. This should bring his hotter signals down to a level the reciever should be able to tune, if there isn't strong multipath present.
Better results will be obtained with newer equipment as tuning technology and multipath rejection technology has been improved with each new generation of tuners. The Samsung SIRT 165 is an example of a better tuner, but it has an auto clock feature that screws up any off air recording timers whan the station that you tune to doesn't have their clock set right. And it has a poor video output, but that can be bypassed via 1394 to the JVC deck.
Jim
The input window doesn't shift. It will tune stations that have a good signal with little to no multipath that are very close to or within the input window (in the case of Richard's 50, that input window is most likely similar to the other 50s window of -25db to -10db). The Joe Kane article has a schematic that shows how to monitor a signal level. With a known level you can either attenuate or amplify a signal to within the input window, however, if strong multipath is present these 1st generation tuners may still have trouble tuning in the signal. Going by the data Richard has provided, I would attenuate the -15db signal down to -18db, then do a new auto scan, if the STB still can't tune the hotter signals, try attenuating to -20db and run auto tune again, and so on. This should bring his hotter signals down to a level the reciever should be able to tune, if there isn't strong multipath present.
Better results will be obtained with newer equipment as tuning technology and multipath rejection technology has been improved with each new generation of tuners. The Samsung SIRT 165 is an example of a better tuner, but it has an auto clock feature that screws up any off air recording timers whan the station that you tune to doesn't have their clock set right. And it has a poor video output, but that can be bypassed via 1394 to the JVC deck.
Jim