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Discussion Starter · #1 ·
I am currently conducting a side-by-side test of four DTV set-top tuners to determine the following:


Sensitivity

Lock-up time

Headroom (how much a DTV signal can be attenuated before drop out)

Heat generation


The tuners are Sony's SAT-HD100, Samsung's SIR-T150, Princeton's HDT2000, and a prototype tuner from Zenith. I'll post what I find out here within the week.


The test will involve 7 stations being received with an indoor antenna.
 

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What type of antenna(s) are you going to try reception on?


I don't know if any stations in your area are running these 'features', but could you check on...


Closed Captioning support

(RCA DTC-100 & Toshiba DST-300 does it)


PSIP Program Guide Support

(RCA DCT-100 does it, Toshiba DST-3000 does not)


Multiple language (SAP) support

(RCA DCT-100 does it, don't know about Toshiba DST-3000 yet)


Thank you. The results will be interesting.


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Kelvin, I would like you to check which ones display the PSIP guide information from the station. If the station is running a complete guide. I know the sony won't.


[This message has been edited by taron1 (edited 05-15-2001).]
 

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Thanks KC, I'm sure we'll all be interested in your findings.


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Kevin,


It would be great if you can include the RCA DCT-100 and Dish 6000. These are prbably the most popular here.


Glenn
 

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Discussion Starter · #7 ·
Okay, here's what I have found out so far:


The minimum discernable signal (MDS) levels - or sensitivity - for all tuners wasn't that different. The SAT-HD100 is actually quite sensitive. With the 7 UHF DTV channels I received, it was as good as or better than the Samsung SIR-T150 in holding a weak 8VSB signal. (Typically -85 dBm was the lowest possible signal, vs. the Samsung's -83 dBm).


The fastest tuner - by far - in locking up a valid 8VSB signal was the Samsung SIR-T150. It locked up some signals as fast as 1.5 seconds after changing channels. The Zenith and Princeton tuners took as long as 4.5 seconds to recognize and lock up some channels (or display a multi-channel stream on the channel guide).


In signal headroom tests, the Sony once again was the best tuner on four of the seven channels, while the Samsung took top honors on the other three. Headroom is defined as how much an 8VSB signal can be attenuated once it is captured, before the signal starts to drop out.


The Sony tuner had a 1 to 6 dB advantage in headroom over the other tuners, depending on the test channels.


Contrary to another post in this topic, the Sony did display program info from the three stations that were transmitting it. This included the virtual chanel, program title, and a short description.


The Samsung tuner also showed a program title where available. Both tuners activate this function from a button marked DISPLAY on the remote.


In some cases, the station had the wrong data up. On Fox, a cartoon came up with "NFL Football" as the program data. Later on, "Ally McBeal" came up over another cartoon.


All the tuners seem to run moderately warm - not hot. The Sopny fan never shuts off (annoying, as many have noted) and the Zenith's fan is quite loud, but shuts down when the tuner is powered off. The Princeton and Samsung tuners do not use fans, but don't seem to suffer for it.


I have not observed any audio dropout on any of the tuners. However, the Sony tuner did have considerable difficulty trying to lock up on a station transmitting the PBS satellite "80-3" PSIP. The SAT-HD100 did recognize the PSIP data, but was never able to lock up the picture. All other tuners locked up this signal right away.


I also observed a strange "posterization" effect on the Sony when receiving some signals with moderate multipath. It's as if the picture solarized, and could only be corrected by switching channels.


The Sony refused to decode any digital audio from the local Fox affiliate. The three other tuners had no such problems.


I will try to post more details from this test soon and will let everyone know the URL for the test results.


KC
 

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Quote:
Originally posted by Kelvin Colorspace:
The fastest tuner - by far - in locking up a valid 8VSB signal was the Samsung SIR-T150. It locked up some signals as fast as 1.5 seconds after changing channels. The Zenith and Princeton tuners took as long as 4.5 seconds to recognize and lock up some channels (or display a multi-channel stream on the channel guide).
I've seen this complaint posted many times with various receivers including the DTC-100. I just started using the DTC-100 for OTA about a month ago and am receiving all 4 digital channels currently being broadcast in my area (Orlando). I haven't noticed any significant delay when changing channels. I punch in the channel number and hit enter and the picture appears. It does take a VERY LONG time to do a channel search though. Am I missing something? On occasion it does take a little longer than "normal" but I don't ever remember it being annoyingly slow.


Jay
 

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Channel changing is dependent on how the broadcaster is sending the signal, the settings on the equipment at the station.
 

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Quote:
Originally posted by Glenn_L:
It would be great if you can include the RCA DCT-100 and Dish 6000. These are prbably the most popular here.
DTC, 6000, and one of the newer Hughes/Tosh/Mits would makes this a very comprehensive analysis and hit the broad population of OTA users.


Also DTC channel changing (up & down) was interminably slow.


Tim


 

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Another critical performance factor to test is the ability to capature and stay locked to signals with severe multi-path. Using some rabbit ears for this test might be appropriate
 

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Quote:


Contrary to another post in this topic, the Sony did display program info from the three stations that were transmitting it. This included the virtual chanel, program title, and a short description.
But did it display the station ID instead of DIGT?. The manual says it should, but mine doesn't even though my DTC-100 & Mits did.


Tony
 

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Quote:
Originally posted by taron1:
Channel changing is dependent on how the broadcaster is sending the signal, the settings on the equipment at the station.
Taron,


In going up & down channel this is definitely untrue in comparitive analysis (at least between Dish 6000, Tosh DTS-3000 & DTC-100, the latter definitely being the noticeable slowpoke).


Tim
 

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In addition to getting multipath, I'm starting to wonder whether my signal is too strong. Are there any differences in the STB's in their ability to avoid being overdriven, and do you know what the symptoms of being overdriven are?


Claude


(PS I've tried an attenuator, but it didn't really help. Perhaps multipath is my ONLY problem.)
 

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While the setting of the PSIP timing can affect the time it takes to actually decode a signal once captured the other delay is how long it takes the equalizer in the tuner to capture the signal. The capture time is related to how much multipath there is and how much processing time is needed optimize the signal. The DTC-100 being a first generation unit has a longer capture time inmost cases than the 6000 or DST-3000.


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Kelvin


I am pleased that the HD100 is showing the PSIP info from your broadcasters. I live in Dallas, and only get the station ID from one of the 7 stations here. All of the others only display DIGT in the upper right corner and Digital Programming where the station ID should be and No Information available where the program info should be.


My DTC100 and DST50 both display the station ID's for the rest of the stations here. Now we need to find out what your stations are doing with the PSIP data that the ones here are not. Can you tell us which stations in your area have PSIP working, CBS, ABC, etc.?


Do the stations you are receiving PSIP data for still show DIGT in the upper right corner or display some station info like the DirecTV stations do?


Thanks for the comparison between units. BTW, I am happy with the HD100 and think once Sony fixes a few bugs, it will be a great unit.


Thanks

warren
 
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