Rowridge Youview HD Channel Fix

[Kenny Saxman]

Hi There,
I just wanted to share this information with you.

Problem - HD channels on YouView (BTvision) such as BBC News Channel freeeze block lose signal retune results in channel being lost completely. All other HD tv's in home receive fine no problem.

Due to 700MHz frequency sell off by the Government free view channels have been shuffled around in the UK, my local transmitter Rowridge is supposed to be a group or band A transmitter horizontally polorized, however last April they moved mux 7 and 8 way up the TV spectrum to channel 57 from memory, band A stops around channel 37, not only this but they changed the polorization from H to V (vertical). Many Rowridge households will as a result lose mux 7 and 8 the HD channels if they have a band or group A aerial or a group A band pass filter in their aerial system (filters were fitted to fix you view box issues in the past).

If you have a HD TV and connect it directly to the room aerial point and you can retune it and recieve the mux 7 and 8 transmissions but fail to get the youview box to detect them on a retune, then there could be a simple fix, this was the problem I had. I purchased a full band 0 - 20 dB variable attenuator from Amazon. I set the adjuster to about half way and placed it in the aerial wall socket feeding the you view box and carried out a retune, I got all channels immediately I then set the youview box to channel 107 (BBC News) and selected signal Quality. The recieved signal strength was at about 40% I adjusted the attuator to get a 90% signal.

I have had this installed for about a week now and have been problem free on my youview box for the first time since last april, no channels are blocking or freezing and reception of all channels is stable.

The problem is due to too much of a good thing the signal strength is so high the cheeper decoders used by humax simply cannot decode the mux channel info and ignore it.

I live in Lyndhurst so if you are nearby and need some help I would be glad to offer some assistance or advice, no charge. I am an Air Traffic Control Voice Comms radio station systems specialist so have a reasonable knowledge.

I just hope this post helps, on the other hand you can wait a couple of years until they shift the Mux 7 and 8 back down to a group A channel.

All the best Kind regards

Kenny

 

[A1944]

Bear in mind that this does not just refer to Rowridge. Most, if not all, COM 7/8 transmitters have moved or will soon move up to 55/56.

 

[Rodders53]

I just hope this post helps, on the other hand you can wait a couple of years until they shift the Mux 7 and 8 back down to a group A channel.

Not a cat's chance in hell of that happening. Ever. Best to hope for is a migration to all DVB-T2 emission when space will become available for the TV channels on 7/8 within the <700MHz muxes.

Your overload issue is probably down to over-amplification of your aerial system and the very sensitive Humax tuners (usually a benefit). Do you have/use a masthead amplifier, or distribution amplifier on your aerial system?

ROW is/should be VP for continental interference reasons... that's why they are emitted at 200kW erp with that polarisation.

Hp was maintained to save viewers replacing aerials at DSO and is still being emitted unchanged from then! With 3 x 200kW and 3 x 50 kW erp. Local and COM7/8 temporaries were added as Hp-only for international frequency clearance (already allocated re-use) reasons - and reduced costs as a result. COM7/8 are 10dB 'weaker' than the main PSB muxes (both now and before they moved frequency).

COM7/8 are on a Single Frequency Network with other transmitters in the 700-800 MHz band as a very temporary service. It's possible that in the SFN constructive interference occurs at your location to give an effectively super-strong signal that upsets the Humax YV boxes?

Certainly, an estimated field for the Lyndhurst Stag Hotel postcode gives 67 dBuV for 200kW erp (61dB for 50kW and 57 dB for 25kW). I get more from Sandy Heath (also group A in analogue days) @ 69 dBuV. At that field overload ought not be an immediate concern, as passive splitting would work well. {Terminated signal strength at TV outlets should be ideally between 45 and 65 dB ref 1uV.}

 

[VisionMan]

Need a bit of an education here - When someone says Humax tuners (inc YouView and Freeview Play) are 'very sensitive', what does that actually mean?

 

[TJT1]

It means that, in either the statement makers opinion or the published specification, that the Humax tuners are more able to receive weaker signals that the ones that they are being compared with.

Nice full stop post BTW

 

[grahamlthompson]

Need a bit of an education here - When someone says Humax tuners (inc YouView and Freeview Play) are 'very sensitive', what does that actually mean?

All amplifiers have a range of input voltages over which the output faithfully follows the input but at a higher voltage. If you design an amplifier that is capable of faithfully creating a higher voltage output without distortion it will allow say a tuner to work with weak signals but if the input voltage is too high the signal peaks are clipped distorting the output. If you have this the signal quality will vary wildly

Fortunately it's very simple to reduce the signal level using a cheap signal attenuator. Many will have aerial amplfiers required when the digital transmitters used low powers to avoid interfering with the analogue TV channels. When the analogue transmitters closed down the digital power output was increased. This means it's very common to now have too high a signal (it's best practice to simply remove any redundant amplification).

I have to attenuate both my HDR-Fox-T2 and FVP-5000T despite being 30 mls from my relay transmitter and having a relatively low gain loft mounted log periodic aerial.

 

[Rodders53]

When the analogue transmitters closed down the digital power output was increased. This means it's very common to now have too high a signal

It is NOT that common. Not that common at all.

Even the 10x DTT power increases are still 1/5 lower (peak) erp than the analogues they replaced (although the power under the curve is very different).

I have no need to attenuate my signal into my -T2 and am much closer to Sandy Heath than you are (to Lark Stoke?). I suspect that overload is more a factor of overall power-saturation within the non-tuned amplifier section of some devices when the aerials see multiple multiplexes from many transmitters. I have only 8 muxes found... you may have more?

(it's best practice to simply remove any redundant amplification).

Agreed.

 

[stblob]

I had this problem living in Portsmouth. I called Freeview and they fitting a new aerial for free. Problem sorted.