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Signal question

T

trog

Well-Known Member
This morning my Aura was reporting no signal on all channels so I tried the TV in my kitchen which is fed by a separate aerial and that also had no signal suggesting and confirmed to be more transmitter works as the cause. My aerial is plugged into RF in on the Aura ( Strength 0% with occasional blip up to 8% and quality 0%) and RF out going to my Samsung TV. My question is why am I able to still get a picture and sound when using the Samsung's tuner albeit with some pixilation and cut outs in audio ? Does the Aura boost it's RF out signal to a strength greater than received by my directly connected kitchen Phillips TV?

Edit I am now getting a perfect pic and audio on my Samsung whilst the Aura and Phillips are still saying no signal
 
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You're in a world of if buts and maybes.

I doubt the Aura provides significant gain on the RF pass-through, because if the signal was already high it could then exceed the linear range on inputs downstream, and if the signal is weak all it would do is amplify the noise as well as the signal and add its own noise contribution on top. The solution to low S/N ratio is a better aerial, not amplification.

It sound to me like the Samsung has better sensitivity.
 
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Black Hole said:
You're in a world of if buts and maybes.

I doubt the Aura provides significant gain on the RF pass-through, because it the signal was already high it could then exceed the linear range on inputs downstream, and if the signal is weak all it would do is amplify the noise as well as the signal and add its own noise contribution on top. The solution to low S/N ratio is a better aerial, not amplification.

It sound to me like the Samsung has better sensitivity.
Click to expand...
Much better it seems, perfect pic now whilst the Aura and Phillips are still zilch.
 
Yes the Aura RF in has an amplifier built in ... It must have. It will be at least 6dB gain* to make up for the theoretical splitting of the signal to the Aura 3 tuners and RF output...

(*in practice closer to 8dB gain will be used).

This merely makes up for the losses in the signal splitter.

Different tuners have different sensitivities and some will work OK with lower signal levels than others.
(All receiver RF input have amplifiers with variable 'automatic gain controls' to cope with a range of signal input levels.)

NB The symptoms quoted do not sound like a transmitter fault to me unless you are in a very fringe location (where large receive aerials and masthead amplification would be the norm. (Post DSO transmitters aren't allowed to be on any significant lower output level.)
BUT Do check the BBC / Freeview / RIS checker for any known problems at your postcode: https://www.bbc.co.uk/reception/problems-freeview-reception#/Freeview to see if there is anything going on.
(Tunbridge Wells aka Pembury had a planned outage yesterday, for instance).
 
Rodders53 said:
Yes the Aura RF in has an amplifier built in ... It must have. It will be at least 6dB gain* to make up for the theoretical splitting of the signal to the Aura 3 tuners and RF output...

(*in practice closer to 8dB gain will be used).

This merely makes up for the losses in the signal splitter.

Different tuners have different sensitivities and some will work OK with lower signal levels than others.
(All receiver RF input have amplifiers with variable 'automatic gain controls' to cope with a range of signal input levels.)

NB The symptoms quoted do not sound like a transmitter fault to me unless you are in a very fringe location (where large receive aerials and masthead amplification would be the norm. (Post DSO transmitters aren't allowed to be on any significant lower output level.)
BUT Do check the BBC / Freeview / RIS checker for any known problems at your postcode: https://www.bbc.co.uk/reception/problems-freeview-reception#/Freeview to see if there is anything going on.
(Tunbridge Wells aka Pembury had a planned outage yesterday, for instance).
Click to expand...
" suggesting and confirmed to be more transmitter works as the cause." I did check at the time and transmitter work was in progress from 10am to 4pm , I was just surprised that my Samsung TV provided any pic and audio when the Aura and Phillips gave none at all and even when the Samsung later gave perfect pic and sound the Aura still stated 0% signal strength and it and the Phillips TV gave nothing but a silent blank screen on all channels. I guess the Samsung has a far superior tuner than the others then.
 
trog said:
??? My aerial only receives a signal from 1 transmitter and the Aura is feeding the signal to the Samsung.
Click to expand...
May I assume that you are in the Pembury, Tunbridge Wells transmitter area?

The ONLY explanation for a signal to the Samsung to work when TW is off air is... reception from another transmitter.

As it happens Tunbridge Wells (vertically polarised) is a Single Frequency Network with Heathfield (horizontally polarised) and there may be enough 'wrong polarisation pickup' via the aerial and/or downlead and cables to allow the sensitive Samsung to work. But insufficient for the other aerial/TV or the Aura.

As it's a SFN then then it's the same frequencies from both sites.
 
Rodders53 said:
May I assume that you are in the Pembury, Tunbridge Wells transmitter area?

The ONLY explanation for a signal to the Samsung to work when TW is off air is... reception from another transmitter.

As it happens Tunbridge Wells (vertically polarised) is a Single Frequency Network with Heathfield (horizontally polarised) and there may be enough 'wrong polarisation pickup' via the aerial and/or downlead and cables to allow the sensitive Samsung to work. But insufficient for the other aerial/TV or the Aura.

As it's a SFN then then it's the same frequencies from both sites.
Click to expand...
I suppose that could be why then though some years ago I did try to get a signal from Heathfield as it gave more channels but could not due to my low location.
 
trog said:
I suppose that could be why then though some years ago I did try to get a signal from Heathfield as it gave more channels but could not due to my low location.
Click to expand...
No idea why you think that.

TW was one of the first 81 DTT sites with 6 multiplexes and even had C5 analogue before DTT.
I'm certain that Heathfield never got the COM7 or 8 DVB-T2 temporaries (interference to the Continent reasons in part).
I guess Heathfield DTT might have been on air slightly earlier than TW but not by a lot.

NB A further check tells me that only the three PSB muxes are SFN from the two sites.
The COM muxes are separate frequencies for TW and Heathfield.
TW has a local TV mux on f,ch 39; so actually broadcasts more TV channels!
 
Rodders53 said:
No idea why you think that.

TW was one of the first 81 DTT sites with 6 multiplexes and even had C5 analogue before DTT.
I'm certain that Heathfield never got the COM7 or 8 DVB-T2 temporaries (interference to the Continent reasons in part).
I guess Heathfield DTT might have been on air slightly earlier than TW but not by a lot.

NB A further check tells me that only the three PSB muxes are SFN from the two sites.
The COM muxes are separate frequencies for TW and Heathfield.
TW has a local TV mux on f,ch 39; so actually broadcasts more TV channels!
Click to expand...
IIRC it was an attempt to get BBC4HD I was not available from TW for a long time.
I got up this morning at 5.15 and as usual turned on the Tv/Hummy to find BBC1 was gone BBC1HD was fine, all the other stations were gone too apart from the HD ones, back home tonight and they are all back I think, not had time to look too closely though, should I? Whats all this about manual tuning of Com4-6? I am hoping
to find that we are at last getting BBC4HD but knowing T/Wells I will be getting less hmmmph! I did notice Blaze is now 63 from 80 and I have Paramount now but no time tonight to even re-do my favourites list or schedule, I really should dive in a get the customised firmware set up shouldnt I.

Needless to say I am getting my signal from T/Wells




BBC Four HD and CBeebies HD temporarily suspended on Freeview > RXTV info​

Viewers retuning find on-screen messages advising them to switch to the standard definition versions of BBC Four HD and CBeebies HD.
rxtvinfo.com

If correct it is good news for me, I have never had BBC4HD but I may get it soon.
 
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