tiffy2 - 15 hours ago »
@grahamlthompson:
Quote: What signal strength and quality do you get on both the RTE HD and SD channels.
On RTE SD transponder, 75/100 (Strength/Quality)
On RTE HD transponder, 79/100 (Strength/Quality)
Re-tested UK transmissions:
On SD transponders, 54/100 (Strength/Quality)On HD transponder, 67/100 (Strength/Quality)
A very long shot can you plug in a variable attenuator and reduce the UK HD signal level to match the SD one.
@grahamlthompson:
Many thanks for your continuing interest and suggestions, much appreciated.
I don't have access to a variable attenuator, I do have a set of fixed, co-axial attenuators somewhere but can't find at present!
While I have never accurately recorded my signal levels & quality before I have absolutely no reason to believe that anything has changed with my antenna or distribution system recently that could have triggered the fault.
While totally accepting your much superior knowledge on the subject, my simplistic logic leads me to believe that a hardware or software fault has developed in the receiver and the fact that only UK HD transmissions are effected, accepting that RTE HD transmissions are known to be "different" (still use the DVB-T standard)and no SD transmissions are effected, this surely must be telling us something.
Switched on the box last night as per normal and the fault has mysteriously gone away, re-checked UK & RTE signal strength & quality levels, all exactly as they were with the fault active, no changes!
Still OK today, strange, will the issue return, who knows?
tiffy2 - 2 hours ago »
Switched on the box last night as per normal and the fault has mysteriously gone away, re-checked UK & RTE signal strength & quality levels, all exactly as they were with the fault active, no changes!
Still OK today, strange, will the issue return, who knows?
The only thing I can think of is co channel interference under high pressure atmospheric uplift conditions. Because signals travel further a distant transmitter using the same uhf carriers can interfere with your local transmitter.
http://www.stevelarkins.freeuk.com/tropo_condx.htm
This goes away when the high pressure moves away.
The UK HD transmitters use a Forward error correction that increases the band width of each mux at the expense of making the signal less robust.
I really don't think it's down to DVB-T2. DVB-T2 increases the capacity of each Mux compared to DVB-T modulation.
grahamlthompson - 1 hour ago »
The only thing I can think of is co channel interference under high pressure atmospheric uplift conditions. Because signals travel further a distant transmitter using the same uhf carriers can interfere with your local transmitter.
But if the problem was co-channel interference, how would you explain the observation that playing programs with a small time shift works properly? NB I have run out of ideas.
Graham & Martin,
Thanks to both for your further interest.
I ran out of ideas a few days ago!
Only time will tell if the anomaly will return?
Last night the issue returned effecting UK HD broadcasts only except now, it's more pronounced with the video freezing/pixilating and the audio blanking, appears to be classic indications of poor signal, indeed, this dialogue will periodically appear on the screen.
The previous work around of pausing live TV for a few seconds does not now work, all SD transmissions are normal, RTE HD transmissions are normal.
Direct TV antenna connection produces the same results on UK HD broadcasts.
Surprisingly, all indicated signal and quality levels remain as previously recorded.
Looks like the previous issue may well have been broadcast related rather than recorder related after all, issue still the same today.
Most of my neighbours use Sky so can't really get a local second opinion.
tiffy2 - 1 hour ago »
Last night the issue returned effecting UK HD broadcasts only except now, it's more pronounced with the video freezing/pixilating and the audio blanking, appears to be classic indications of poor signal, indeed, this dialogue will periodically appear on the screen.
What compass directions and distances are the two transmitters you are receiving from? Now the symptoms sound more like some sort of co-channel interference.
The transmitters are due west, only a few deg's. apart with the RTE tx. physically located in county Donegal.
The UK tx. is a local repeater using ch's. 41,44 & 47, vertical polarisation.
The RTE tx. uses ch's. 30 & 33 and is horizontally polarised.
Use 2 suitably grouped external yagi's, mast diplexed using a good quality, metal bodied, filtered diplexer to a single feeder.
To the best of my knowledge, have never had any co-channel interferance issues to date.
After a year of perfect operation the issue returned yesterday, exactly the same in all respects, only effects UK HD live broadcasts RTE HD perfect, all recordings from any source SD or HD perfect, very strange !
Perhaps it's time for a PVR change, the unit is just short of 5 years old now.
Could I expect a replacement model to support LAN access to my NAS and USB connection to an external HD, what's the best current unit at a reasonable cost, don't need a gigantic internal HD ?
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