622 OTA signal loss

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
This topic has been discussed in many different threads, but I decided to start a new one because I'm taking a different track in trying to solve the problem.

In my area of southeastern VA, we have one DT-OTA station that has been giving reception problems to many people with different OTA receivers and including myself when using the 622. I also have a ATSC tuner in a Mits LCD, which does not have any problem in handling the signal from this station.

The 622 image is pixelated, sound is garbled and frequently, the "Loss of OTA Signal" error message pops up on the screen. Other threads gave me a clue about padding down the signal to eliminate this problem, so I inserted a switchable attenuator in-line to the 622 and found I had to insert 21 dB of attenuation before the problem disappeared, but then my weaker stations were flaky. This requires changing the attenuation when switching channels, not a great situation for unattended recordings.

I know some people have deduced this problem is caused my multipath errors or signal overload, but in my case, analog stations on either side of the DT station show no signs of multipath errors and in fact one of them is delivered from the same tower as the problem DT station. Also, the problem station is not the strongest in the area.

I'm thinking that this problem is not really connected to "loss of signal" rather caused by "loss of sync." Also, the problem isn't caused by multipath errors, but with some other signal condition that affects the 622 and not other tuners.

I'm hoping there will be some person on this list that might shed some light on what other signal conditions might cause this problem where inserting attenuation pads takes care of the situation. Something along the lines of signal non-linearities such as spikes?
 

kstile

SatelliteGuys Pro
Oct 7, 2005
258
0
I can relate to the "loss of sync" notion on the 622. I am forced to get FOX-HD OTA here in Seattle because Dish won't carry it (dispute with the station's owner). I get all the other local HD stations OTA just fine, but Fox is always a bit flaky. Last night, for instance, during "24" it was perfect - my signal strength was 72-75 for the entire broadcast.

However, I have seen other times where the signal is at 70+, drops to 0, and then comes right back to 70+. The signal is strong and then drops out completely for a few seconds (sometimes a few minutes) and then goes back to being fine for a whle. It's intermittent but I can't find a common situation (weather, etc.) when it's not working right.

I know this doesn't really address your concern, but your description of "loss of sync" is exactly what I seem to have with this station.
 

cebbigh

Supporting Founder
Supporting Founder
May 24, 2005
1,601
0
Frostbite Falls
I can relate to the "loss of sync" notion on the 622. I am forced to get FOX-HD OTA here in Seattle because Dish won't carry it (dispute with the station's owner). I get all the other local HD stations OTA just fine, but Fox is always a bit flaky. Last night, for instance, during "24" it was perfect - my signal strength was 72-75 for the entire broadcast.

However, I have seen other times where the signal is at 70+, drops to 0, and then comes right back to 70+. The signal is strong and then drops out completely for a few seconds (sometimes a few minutes) and then goes back to being fine for a whle. It's intermittent but I can't find a common situation (weather, etc.) when it's not working right.

I know this doesn't really address your concern, but your description of "loss of sync" is exactly what I seem to have with this station.

My current signal strength for KCPQ varies between 65-68. Inserting a DC block seems to eliminate the drops to 0 and increases stability but does nothing to improve overall signal strength. Out of desperation I've tried the Rat Shack adjustable attenuator for KCPQ and it didn't help.
 

kstile

SatelliteGuys Pro
Oct 7, 2005
258
0
What, exactly (Radio Shack part number?) is a "DC Block" and where would I insert it? If I can eliminate the drops to 0, I'd be perfectly happy with KCPQ OTA. Thanks.
 

wayne231

SatelliteGuys Pro
Feb 9, 2006
215
0
Memphis, TN
This is a problem I have had for aprox. 6 weeks now and have been in contact with Dish engineers with. My problem is with the local Fox station. I was informed by thier engineer that they began using a new encoder around the time Dish lost distants (how fortunate for them when *D was trying to get Dish subs.) If you are having this problems please state which network it is so that this can be transmitted to the engineers. It will help a lot. They are currently in talks with certain stations and with the mfg. of thier OTA tuners.
Thanks.
PS: Can this be made a sticky as this is becoming a big problem for OTA Dish customers?
 

spudz160

SatelliteGuys Family
Nov 8, 2004
42
0
Duluth, MN
I too have this issue with the local FOX station KQDS Duluth. Does anyone have issues with stations other then FOX? I have between 80 and 90 percent (I can see the towers from my living room) and the staion works fine with the tuner in the TV.
 

lrossnm

SatelliteGuys Family
May 17, 2004
80
0
Santa Fe, NM.
I too have this issue with the local FOX station KQDS Duluth. Does anyone have issues with stations other then FOX? I have between 80 and 90 percent (I can see the towers from my living room) and the staion works fine with the tuner in the TV.

Last night , during 24 , I lost the signal from my OTA Fox station ( Albuquerque) twice. I had to switch my 622 to another station and then back to Fox to get the signal back. I'm about 50 miles from the towers.
 

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
This is a problem I have had for aprox. 6 weeks now and have been in contact with Dish engineers with. My problem is with the local Fox station. I was informed by thier engineer that they began using a new encoder around the time Dish lost distants (how fortunate for them when *D was trying to get Dish subs.) If you are having this problems please state which network it is so that this can be transmitted to the engineers. It will help a lot. They are currently in talks with certain stations and with the mfg. of thier OTA tuners.
Thanks.
PS: Can this be made a sticky as this is becoming a big problem for OTA Dish customers?

My problem is with WAVY-DT in Norfolk, VA. Also, I'm not the only one in this area having a problem with receiving WAVY OTA.

Two things to remember in my case:

1. My Mits LT-37131 LCD has no problem receiving this signal at full strength.

2. I'm inserting 21 dB of attenuation to the 622 in order to settle it down. This amount of attenuation creates a problem with a weaker station.

Finally, I'm 35 miles from the station so overload doesn't appear to be the problem.
 

boy921

SatelliteGuys Pro
Apr 24, 2004
391
0
N. California
Problem with FOX TV KCVU DMA 130

http://www.satelliteguys.us/showthread.php?t=58689

I posted my recent experience with the my Local FOX TV station's OTA channel. Here is what I posted:

"In my DMA the FOX TV channel is causing the exact same problem. It started Jan. 09, 07 when they returned to the airwaves having been off the air for two days. Like you, only the 622 (and other local users of 622's and 211's) are affected. My regular HDTV ATSC tuners work fine with the channel.

I contacted the FOX TV station and after about seven phone calls, they actually went to the transmitter and tinkered while using me as a trouble shooting component. When they reversed their temporary fix (putting the signal a low power) the 622 worked fine. When they reinstalled their temporary fix the 622 started having problems again. The problem will continue until the receive and install new parts.

I have seen posts in other forums where people at different locations are having the same problem with the FOX channel.

The engineers at my FOX TV station assured me that they have added no new equipment and/or software upgrades.

I contacted advanced tech support at E* and they placed a trouble report with their engineering."
 

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
http://www.satelliteguys.us/showthread.php?t=58689

When they reversed their temporary fix (putting the signal a low power) the 622 worked fine. When they reinstalled their temporary fix the 622 started having problems again. The problem will continue until the receive and install new parts.

I have seen posts in other forums where people at different locations are having the same problem with the FOX channel.

The engineers at my FOX TV station assured me that they have added no new equipment and/or software upgrades.

I contacted advanced tech support at E* and they placed a trouble report with their engineering."

I'm not sure what you're saying. Did the engineers at your Fox station identify the problem at the transmitter? If so what was the cause? Or is this condition caused by a problem in the 622 OTA receiver?
 

boy921

SatelliteGuys Pro
Apr 24, 2004
391
0
N. California
The problem was at the transmitter which is about 35 miles away from the station. The engineers would not elaborate as to the exact parts causing the problem. What is strange is that it affects 622's and 211's. DirectTV ATSC tuners and other brands of ATSC tuners work fine with their temporary fix. The temporary fix is causing some non-compliant signal respective to 622/211 receivers. The majority of time when there are signal problems with any stations, the 622 always suffers the worst.
I'm not sure what you're saying. Did the engineers at your Fox station identify the problem at the transmitter? If so what was the cause? Or is this condition caused by a problem in the 622 OTA receiver?
 

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
The majority of time when there are signal problems with any stations, the 622 always suffers the worst.

I've described this problem to a group of RF engineers who have a bit of experience with ATSC transmission systems. The prevalent thinking is the condition is caused by another station's signal, either adjacent channel, co-channel, or some harmonic of a channel that falls into the problem channel's frequency and it might be poor selectivity of the 622's front end that's causing the problem. I've searched FCC files and have found no adjacent channel or co-channel that could be causing the problem. Don't know how to determine if harmonics of other channels might be interfering with WAVY's signal.
 

boy921

SatelliteGuys Pro
Apr 24, 2004
391
0
N. California
barrysb,

This sounds like very good information. I will pass it on to the engineers at my affected station.

I did receive a phone call from an engineer this afternoon. They had received and have installed their new parts. They wanted to know if the problem still persisted. The same problem still persists.

I did get some good information. The engineer described the part as an, "Exciter" used at the transmitter. He said the old one broke, hence no signal for two days. They replaced it with a loaner from the transmitter manufacturer until they could get the new part. The engineer mentioned that the manufacture is aware that there is a problem in the exciter so the engineer was led to believe that they got the newest software version to remedy the problem. It sounds like the new software may contribute to the problem as it may have been present in the loaner part.

I appreciate your information and will post back with any concrete information.

Thanks.

John

PS - There is a very close digital transmitter for another station one hundred feet below and in front of my site of the problem transmitter.

I've described this problem to a group of RF engineers who have a bit of experience with ATSC transmission systems. The prevalent thinking is the condition is caused by another station's signal, either adjacent channel, co-channel, or some harmonic of a channel that falls into the problem channel's frequency and it might be poor selectivity of the 622's front end that's causing the problem. I've searched FCC files and have found no adjacent channel or co-channel that could be causing the problem. Don't know how to determine if harmonics of other channels might be interfering with WAVY's signal.
 

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
barrysb,

This sounds like very good information. I will pass it on to the engineers at my affected station.

PS - There is a very close digital transmitter for another station one hundred feet below and in front of my site of the problem transmitter.

This other digital transmitter could be interfering with your problem station. However, you mentioned something in your first posting which might be an additional clue to what is causing the problem. You wrote you did not have the problem when the station was transmitting at low power. I've found that reducing the signal level into the 622 solves my problem. Now if it can be proved that either of these conditions solve the problem, it throws out what I wrote in my last posting. i.e. it is not co-channel, adjacent channel, or harmonics that is causing the problem. Rather, it has something to do with some signal condition, which in your case could be overload, but probably is some other condition at my location. My problem station is not the strongest of signals coming off my antenna.
 

boy921

SatelliteGuys Pro
Apr 24, 2004
391
0
N. California
The process of elimination is not helping. For months I received FOX - KCVU DT while they were at full power with no problems, KHSL DT is the other nearby transmitter. They have made no changes. The problem only started after KCVU DT installed a loner, and then new, "Exciter" that has a different software version than the one that died.

I have connected my most directional antenna alone with no padding, with padding, with and without splitters/combiners, and with and without amplifiers. The problem is exactly the same at any signal level with any configuration. The symptoms are just like multi-path, but the out-of-phase signal is coming from the same direction, the transmitter. KCVU DT signal is above average (84%), the transmitter is 54 miles away. I receive a 100% signal from KNVN DT transmitter that is about 35 miles away. The KNVN DT signal is clean. Reception of the digital channels, even with amplification works fine as do the other digital channels in my DMA. IMHO KCVU DT signal is dirty and E*'s 622/211 ATSC tuners are rigidly set to minimum standards/basics.

One possibility is that KCVU DT signal is being reflected on a newly located reflective surface between me and their transmitter or the signal is being rebroadcast on the same channel from another location (which KCUV assures me, is not the case). It is likely that something causing a harmonic like or phasing shift. However, it would be logical that my early generation ATSC tuners would also experience multi-path with these scenarios.

This other digital transmitter could be interfering with your problem station. However, you mentioned something in your first posting which might be an additional clue to what is causing the problem. You wrote you did not have the problem when the station was transmitting at low power. I've found that reducing the signal level into the 622 solves my problem. Now if it can be proved that either of these conditions solve the problem, it throws out what I wrote in my last posting. i.e. it is not co-channel, adjacent channel, or harmonics that is causing the problem. Rather, it has something to do with some signal condition, which in your case could be overload, but probably is some other condition at my location. My problem station is not the strongest of signals coming off my antenna.
 

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
The process of elimination is not helping. For months I received FOX - KCVU DT while they were at full power with no problems, KHSL DT is the other nearby transmitter. They have made no changes. The problem only started after KCVU DT installed a loner, and then new, "Exciter" that has a different software version than the one that died.

I have connected my most directional antenna alone with no padding, with padding, with and without splitters/combiners, and with and without amplifiers. The problem is exactly the same at any signal level with any configuration.

Do you have any idea how much attenuation you've inserted when trying these different configurations? I happened to have a switchable RF attenuator, which has 3/6/12 dB pads and had to switch all of them into the antenna connection to the 622 before my problem station settled down. That's a fair amount of attenuation.
 

boy921

SatelliteGuys Pro
Apr 24, 2004
391
0
N. California
Attenuation from 5~20 no help. There is a problem with the transmission and the 622. The TV station is trying to get it fixed.
Do you have any idea how much attenuation you've inserted when trying these different configurations? I happened to have a switchable RF attenuator, which has 3/6/12 dB pads and had to switch all of them into the antenna connection to the 622 before my problem station settled down. That's a fair amount of attenuation.
 

barrysb

SatelliteGuys Family
Sep 11, 2003
76
0
Attenuation from 5~20 no help. There is a problem with the transmission and the 622. The TV station is trying to get it fixed.

I'll be interested in knowing what you find out, hopefully, with some specific info as to what the engineers did at the station to solve the problem.
 

dogpoobob

Supporting Founder
Supporting Founder
Jan 10, 2005
165
1
Brighton, TN (near Memphis)
This is a problem I have had for aprox. 6 weeks now and have been in contact with Dish engineers with. My problem is with the local Fox station. I was informed by thier engineer that they began using a new encoder around the time Dish lost distants (how fortunate for them when *D was trying to get Dish subs.) If you are having this problems please state which network it is so that this can be transmitted to the engineers. It will help a lot. They are currently in talks with certain stations and with the mfg. of thier OTA tuners.
Thanks.
PS: Can this be made a sticky as this is becoming a big problem for OTA Dish customers?

I have been having this problem for some months now and the Fox 13 (channel 53) in Memphis has been trying to pinpoint the problem. Others subs (other than E*) are having the problem also, but I hooked my old VoOM STB and get perfect reception.
 
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