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Old 09-11-2014, 16:00
Bulletguy1
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Well guys despite all yer 'dbs' and elements etc i'm beginning to wonder now if my problem may be something to do with the PVR itself!

I've been recording the whole series of HIGNFY on BBC1. Never been a problem before but i lost almost half of Fridays episode with what appears to be broken signal giving a badly pixellated picture. I scrolled it forwards gradually then around 15 mins in.....all was clear and normal service resumed!!

BBC1 is possibly one of the strongest signals for my area so that's why i'm wondering about the PVR....which is only a few months old.

Anyway, i've read through the posts from the 'techno freaks' (reminded me of my days with illegal AM/CB and the debates over 'the right aerials' ), so here is a bit more background info.

My location is CW3 which is Cheshire/Staffs so Winter Hill (Granada) is the transmitter most use around here, but i don't like Granada ITV so have my aerial set to Sutton Coldfield to give me Midlands ITV. A few other neighbours have done likewise.

I don't experience any problem such as described above when viewing a programme direct from the TV so i cannot say it's specific just to one channel as it's occurred on others.....but only when recorded on the PVR.

Discovered a snippet of trivia which i never knew before....Sutton Coldfield has broadcast terrestrial television signals every day since 1949 and is the oldest working television transmitting station in the world.
(I could almost hear Clarkson saying that!)
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Old 09-11-2014, 18:16
Chris Frost
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Based on what you added, another possibility then is too much signal. It's one of those curiosities of digital. There's a band of acceptable signal powers. If the strongest mux is causing issues but the weakest isn't then it's not insufficient signal. Have a look at the signal quality and signal strength indicators. Quality is the most important. Strength is less so. A variable attenuator is a simple and cheap tool to use for diagnosis. If there's too much strength then quality will actually go down. Reducing strength allows quality to go back up.

There could also be attenuation at a specific frequency if the cable is kinked or bend. See link This can cause a notch filter effect where some frequencies are affected but not others.
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Old 09-11-2014, 18:55
Winston_1
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Based on what you added, another possibility then is too much signal. It's one of those curiosities of digital. There's a band of acceptable signal powers. If the strongest mux is causing issues but the weakest isn't then it's not insufficient signal. Have a look at the signal quality and signal strength indicators. Quality is the most important. Strength is less so. A variable attenuator is a simple and cheap tool to use for diagnosis. If there's too much strength then quality will actually go down. Reducing strength allows quality to go back up.

There could also be attenuation at a specific frequency if the cable is kinked or bend. See link This can cause a notch filter effect where some frequencies are affected but not others.
Basically true, but too much signal is not a curiosity of digital. It applied to analogue as well.
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Old 09-11-2014, 20:45
niall campbell
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You could also go for WF 100 cable from Satcure
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Old 09-11-2014, 20:57
Bulletguy1
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You could also go for WF 100 cable from Satcure
Thanks for that. Been poking around in their site as i've just gone to record on the PVR and it's come up as "no available signal" on both BBC1 & 2.
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Old 09-11-2014, 21:05
Chris Frost
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Basically true, but too much signal is not a curiosity of digital. It applied to analogue as well.
Okay, but given that digital is far easier to over saturate, especially if the aerial system was originally installed for analogue, you have to agree that far more people are likely to encounter oversaturation with digital than analogue.
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Old 09-11-2014, 21:59
niall campbell
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Thanks for that. Been poking around in their site as i've just gone to record on the PVR and it's come up as "no available signal" on both BBC1 & 2.
I see you had an A Band aerial.

Can you tell us what transmitter you are getting your signal from please

Does your TV pick up BBC 1 & BBC 2 ok ?

Aerial straight to Humax and then up to TV ?
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Old 09-11-2014, 22:21
grahamlthompson
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I see you had an A Band aerial.

Can you tell us what transmitter you are getting your signal from please

Does your TV pick up BBC 1 & BBC 2 ok ?

Aerial straight to Humax and then up to TV ?
Sutton Coldfield. See the OP's original post.

I imagine the OP has used autotune and has as a result got reception from the stronger local transmitter and also Sutton Coldfield (possibly more) with the required channels appearing in the 800+ channel numbers, The solution is manual tuning, need the specific Humax PVR model number to help further.
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Old 09-11-2014, 22:47
Bulletguy1
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I see you had an A Band aerial.

Can you tell us what transmitter you are getting your signal from please

Does your TV pick up BBC 1 & BBC 2 ok ?

Aerial straight to Humax and then up to TV ?
Sutton Coldfield transmitter.

Yes TV picks the signal up no problem and this is whats strange......i have actually had a signal plus recorded on both those channels previously eg. full episodes of HIGNFY recorded without problems.

Yes aerial co-ax goes straight to Humax then to TV.

Sutton Coldfield. See the OP's original post.

I imagine the OP has used autotune and has as a result got reception from the stronger local transmitter and also Sutton Coldfield (possibly more) with the required channels appearing in the 800+ channel numbers, The solution is manual tuning, need the specific Humax PVR model number to help further.
It's a Fox T2.
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Old 10-11-2014, 08:55
grahamlthompson
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Sutton Coldfield transmitter.

Yes TV picks the signal up no problem and this is whats strange......i have actually had a signal plus recorded on both those channels previously eg. full episodes of HIGNFY recorded without problems.

Yes aerial co-ax goes straight to Humax then to TV.

It's a Fox T2.
Have you channels with channel numbers over 800 ?

How far are from Sutton Coldfield ? (You may need a signal attenuator).
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Old 10-11-2014, 09:58
White-Knight
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Ten times gain is 10bB, with 3dB usually considered the smallest change you can usually notice.
I stand corrected.

Up to 10dB it's less. I understand that after 10dB there's a ten fold increase for every dB. eg 10db is 10x the signal strength, 20db is 100x the signal strength, 30db is 1,000x the signal strength.
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Old 10-11-2014, 10:00
White-Knight
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@OP, you might find this helpful, you type in your postcode, and it gives you the bearing and strength of every tv transmitter in your area and recommends the aerial type (and thus gain required ie low, mid, high, very high)

http://www.wolfbane.com/cgi-bin/tvd.exe?MAP=661,936

So for example if I put in the fictional B76 5CJ, you get:

http://www.wolfbane.com/cgi-bin/tvd....=10&OS=B76+5CJ
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Old 10-11-2014, 10:16
chrisjr
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I stand corrected.

Up to 10dB it's less. I understand that after 10dB there's a ten fold increase for every dB. eg 10db is 10x the signal strength, 20db is 100x the signal strength, 30db is 1,000x the signal strength.
Decibels are logarithmic.

The formula is 10 x log(P1/P2) where P1 and P2 are the two powers involved.

So for every ten decibels the power increases by a factor of ten eg from 20W to 200W. A single decibel increase represents about a factor of 1.25 increase in power, eg from 20W to 25W
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Old 10-11-2014, 11:03
bobcar
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I stand corrected.

Up to 10dB it's less. I understand that after 10dB there's a ten fold increase for every dB. eg 10db is 10x the signal strength, 20db is 100x the signal strength, 30db is 1,000x the signal strength.
The figures you've quoted correctly show a 10 times increase for every 10dB increase i.e. 20dB to 30dB goes from x100 to x1000. There is no difference below 10dB and you can even go negative for example -20dB is divide by 100.

The important thing to remember is that dB is a ratio there is no absolute level so the value in dB will always be a multiple of whatever 0dB is set to which will vary according to what you are measuring (things like dBm are specific).
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Old 10-11-2014, 11:54
Nigel Goodwin
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I stand corrected.

Up to 10dB it's less. I understand that after 10dB there's a ten fold increase for every dB. eg 10db is 10x the signal strength, 20db is 100x the signal strength, 30db is 1,000x the signal strength.
Sorry, but you're not understanding at all

10dB is ten times, regardless of where it is.

The difference between 10dB and 20dB is 10dB, so the first 10dB is ten times, the second 10dB another ten - 10x10 gives you 100 times - likewise another ten gives you 10x10x10 = 1000 times.
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Old 10-11-2014, 13:33
niall campbell
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Sutton Coldfield transmitter.

Yes TV picks the signal up no problem and this is whats strange......i have actually had a signal plus recorded on both those channels previously eg. full episodes of HIGNFY recorded without problems.

Yes aerial co-ax goes straight to Humax then to TV.

It's a Fox T2.
If I was you, I would consider replacing your A band aerial with a Wideband one and insist on WF100 cable.

However, before doing that I would attempt to rectify your problem. If you have a wallplate for your tv point , I would try and get a fly lead between the wall and your Humax, and then up to your tv; made of WF 100 cable.

It seems from here that there is a possibility of interference when you Humax starts recording, or going by the posts on this website, audio problems albeit on a repeater transmitter.

http://www.ukfree.tv/transmitters/tv/Sutton_Coldfield

If you have a chance with a long lead of aerial going into the Humax, then tightly coil the RF cable before it goes into the Humax. WITHOUT breaking it !!
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Old 10-11-2014, 13:39
Nigel Goodwin
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If I was you, I would consider replacing your A band aerial with a Wideband one and insist on WF100 cable.
Using a group A aerial is likely to be part of his problem, Sutton Coldfield was historically group B, but now has some higher channels as well, so wideband is recommended.

Group A aerials are pretty useless for higher frequencies, bizarrely enough CD aerials work far better on lower channels than A aerials work on higher ones.
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Old 10-11-2014, 14:00
niall campbell
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Group A Ch 21 up to CH 37

Group B Ch 35 up to CH 53

Group C/D Ch 48 up to Ch 68

Group K Ch 21 up to Ch 48

Group Ch 35 to Ch 68

Group W WIDEBAND Ch 21 up to Ch 68

Group T Ch 21 to Ch 60 revised post switchover ( Full ) band

I would go for Wideband and cover all bases



Mux Aerial position Frequency Height Mode Watts
PSB1
BBCA
horizontal max
C43 (650.0MHz) 433m 64QAM 8K 2/3
24.1Mb/s DVB-T MPEG2 200,000W
Channel icons
1 BBC One West Midlands, 2 BBC Two England, 7 BBC Three, 9 BBC Four, 120 CBBC, 121 CBeebies, 130 BBC News, 131 BBC Parliament, 301 BBC Red Button 1, plus 13 others


PSB2
D3+4
horizontal max
C46 (674.0MHz) 433m 64QAM 8K 2/3
24.1Mb/s DVB-T MPEG2 200,000W
Channel icons
3 ITV (Central (West micro region)), 4 Channel 4 Midlands ads, 5 Channel 5 Part Network ads, 6 ITV 2, 13 Channel 4 +1 Midlands ads, 14 More 4, 15 Film 4, 28 E4, 33 ITV +1 (Central west),


PSB3
BBCB
horizontal max
C40+ (626.2MHz) 433m 256QAM 32KE 2/3
40.2Mb/s DVB-T2 MPEG4 200,000W
Channel icons
101 BBC One HD (England no regional news), 102 BBC Two HD (England), 103 ITV HD (ITV Central West), 104 Channel 4 HD Midlands ads, 105 BBC Three HD, 123 CBBC HD, plus 1 others


COM4
SDN
horizontal max
C42 (642.0MHz) 433m 64QAM 8K 3/4
27.1Mb/s DVB-T MPEG2 200,000W
Channel icons
10 ITV 3, 20 Drama, 25 Dave ja vu, 26 ITV Be, 27 ITV 2 +1, 30 5*, 31 5USA, 34 ITV 3 +1, 37 Quest, 44 Channel 5 +1, 55 Channel 5 +24, 61 True Entertainment, 62 ITV 4 +1, 66 CBS Reality, 122 CITV, plus 21 others


COM5
ArqA
horizontal max
C45 (666.0MHz) 433m 64QAM 8K 3/4
27.1Mb/s DVB-T MPEG2 200,000W
Channel icons
BBC Red Button 2, 11 pick, 12 Dave, 17 Really, 29 E4 +1, 32 Movie Mix, 38 Quest +1, 41 Food Network, 42 Travel Channel, 46 Challenge, 48 Movies4Men, 63 Community Channel, 68 truTV, 69 truTV +1, 126 Tiny Pop, 132 Sky News, 242 Vintage TV, plus 11 others


COM6
ArqB
horizontal max
C39+ (618.2MHz) 433m 64QAM 8K 3/4
27.1Mb/s DVB-T MPEG2 200,000W
Channel icons
18 4Music, 19 Yesterday, 21 VIVA, 24 ITV 4, 45 Film 4 +1, 47 4seven, 58 BT Sport 1 (not free), 59 BT Sport 2 (not free), 70 CBS Action, 133 Al Jazeera English, 135 RT English , plus 22 others


LB
horizontal -13dB
C51 (714.0MHz) 433m QSPK 8K 3/4
8.0Mb/s DVB-T MPEG2 10,000W
Channel icons
from 31st October 2014: 8 City TV Broadcasting, 67 Chart Show TV, 125 Pop, plus 1 others


com7
horizontal -3.5dB
C33 (570.0MHz) 433m 256QAM 32KE 2/3
40.2Mb/s DVB-T2 MPEG4 89,200W
Channel icons
71 Motors TV, 106 BBC Four HD, 107 BBC News HD, 108 Al Jazeera HD, 109 Community Channel HD, 110 Channel 4+1 HD, 111 4seven HD, 124 CBeebies HD, 134 Al Jazeera Arabic, plus 1 others


com8
horizontal -13.8dB
C35 (586.0MHz) 433m 256QAM 32KE 2/3
40.2Mb/s DVB-T2 MPEG4 8,300W
Channel icons
starts sometime during 2014:
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Old 10-11-2014, 15:30
White-Knight
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Sorry, but you're not understanding at all

10dB is ten times, regardless of where it is.

The difference between 10dB and 20dB is 10dB, so the first 10dB is ten times, the second 10dB another ten - 10x10 gives you 100 times - likewise another ten gives you 10x10x10 = 1000 times.
Yeah confused 10x with 1o increments. Nevermind, all correct now. Still a big increase though per db.
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Old 10-11-2014, 16:39
Nigel Goodwin
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Yeah confused 10x with 1o increments. Nevermind, all correct now. Still a big increase though per db.
Not at all, 1dB is too small to notice - 3dB is generally considered the smallest change that makes any difference.
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Old 10-11-2014, 16:41
Bulletguy1
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Have you channels with channel numbers over 800 ?

How far are from Sutton Coldfield ? (You may need a signal attenuator).
50 miles by road so 'as the crow flies'.....less.

If I was you, I would consider replacing your A band aerial with a Wideband one and insist on WF100 cable.

However, before doing that I would attempt to rectify your problem. If you have a wallplate for your tv point , I would try and get a fly lead between the wall and your Humax, and then up to your tv; made of WF 100 cable.

It seems from here that there is a possibility of interference when you Humax starts recording, or going by the posts on this website, audio problems albeit on a repeater transmitter.

http://www.ukfree.tv/transmitters/tv/Sutton_Coldfield

If you have a chance with a long lead of aerial going into the Humax, then tightly coil the RF cable before it goes into the Humax. WITHOUT breaking it !!
Been looking through that Satcure site which seems to have everything and going by what others said on here, this appears to be the best aerial if i replace. Unless you suggest otherwise?

Yes i've no doubt the cable must certainly be 'well weathered' by now as it's been up there for 20 years.

However......now for the good news.

Weather conditions were clear earlier on so i spent time going through the PVR menu. It's a bit frustrating as it's more 'fussy' than the Humax Freesat which was simple to re-tune. The Fox T2 wouldn't let me get to tuning without keying in a damn pass key which i ignored as i'd never put one in. Turned out it's already set default at 0000 which you have to key to get to tuning......but it doesn't tell you that in the damn manual!

So......did a full re-tune and hey presto......all channels up working perfectly.

Quite why/how i had lost the signals in the first place i've no idea. As explained in other posts, i'd previously recorded to the PVR without problems.
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Old 10-11-2014, 17:07
chrisjr
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The Fox T2 wouldn't let me get to tuning without keying in a damn pass key which i ignored as i'd never put one in. Turned out it's already set default at 0000 which you have to key to get to tuning......but it doesn't tell you that in the damn manual!
errrr yes it does.

Page 52 of the manual where it describes the Installation menu where you kick off a retune.

You will be prompted to enter the password to access this menu. The default password is 0000. If you have forgotten your password, please contact Humax Customer Support.
http://grangefarmstudios.co.uk/guide...GB_11-0208.pdf
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Old 10-11-2014, 18:34
Nigel Goodwin
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Turned out it's already set default at 0000 which you have to key to get to tuning......but it doesn't tell you that in the damn manual!
As Chris said, "yes it does"

In any case where you're asked for a PIN number always try 0000 and 1234, those are the two common default values.
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Old 10-11-2014, 21:05
Bulletguy1
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As Chris said, "yes it does"

In any case where you're asked for a PIN number always try 0000 and 1234, those are the two common default values.
Oooh.....should have gone to Specsavers!

Can't ever remember needing to do that with the Freesat one though.

Further update on the aerial biz.....spoke to some guy earlier at Satcure and he lives close to my area so was a bit surprised when i told him i was using Sutton Coldfield. He recommends checking the existing aerial terminals first. If corroded then bin it but if not, just replace the cable.

He told me the quality of co-ax cable 20 years ago was a darn sight better than they turn out now (price for price) so it might still be ok.

Seems a good type of business as he was saying he doesn't like selling stuff people don't really need.

Pleasant surprise!
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Old 10-11-2014, 21:25
niall campbell
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at around £150 or DIY, its a cheap 20 to 30 years life out of an aerial, that's fit for purpose !
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