Certain channels losing signal

B

Bananawls

New Member
I've had my HDR-2000T (1gb) for a fortnight now and it's been working well apart from the occasions when a channel stops receiving any porgrammes. The last time was for BBC 2 (standard def), I can't remember the exact comment but it was about the channel being unavailable, or no signal.

All other channels were ok at that time, even BBC 2 HD.

I think this has happened during a recording too, because the recording failed (it showed the recording time was "0" minutes).

Any ideas why this is happening?
 
Freeview TV channels are grouped together using a single UHF carrier frequency, these groups are called Multiplexes or MUXs, the channels on each MUX can be viewed HERE, (you can sort by MUX), so it is very likely that when you lose BBC 2 (SD) that you will also be losing all the others programmes on the same MUX, you can check the signal strength and the signal quality in the Humax setting menu
 
Ah, I just checked the strength and it is at 29%! That's probably why.

I'm surprised it's that low. My old PVR9200 detected a much stronger signal before I replaced it with this HDR-2000.
 
Signal is probably the same (unless you have altered anything). Tuner and sig strength readouts are probably different.
 
Bananawls said:
Ah, I just checked the strength and it is at 29%! That's probably why.

I'm surprised it's that low. My old PVR9200 detected a much stronger signal before I replaced it with this HDR-2000.
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The HDR-2000T does appear to have tuners that are less sensitive than the earlier Humax PVRs. This may well be by design because there are probably more people suffering problems due to the tuners being over loaded now that DSO has finished and transmitter power is higher, than people suffering with low power. 29% is definitely a bit marginal so either a better aerial, better cabling or an amplifier should sort out the problem. Perhaps worth talking to a local aerial installer for an opinion?
 
Presumably the HDR-2000T has the newer type silicon tuner, rather than the older style CAN tuner? I have HDR-Foxes with both types, and while both tuners are good, I think that the CAN tuners have the edge. Of course, this is anecdotal as tests on a large sample would be needed to rule out unit to unit variation. I also think that the single CAN tuner on the HD-FOX does not perform as well as the dual CAN tuners on the HDR-FOX but this is just based on my own experience.
 
As long as that doesn't suffer drop-outs, you should be fine then. The problem with a percentage strength figure is that we have no idea what 100% represents, or whether 100% is consistent across devices/manufacturers. From an engineering point of view, it would be sensible to make the 100% signal level the point at which the input saturated, but who knows.
 
Bananawls said:
Despite the signal being at 29%, the quality level = 100%.
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My point is that at 29% signal strength you don't have much margin for anything adverse happening and your original post was complaining about occasional loss of reception. We operated one of our boxes with signal strengths less then 30% for some time without problem but we are only a mile of the local transmitter and in line of sight.
 
There are significant differences in the reported signal strength values, even between individual HDR-FOX units. Using the channel 'Pop' as an example (local MUX, Sutton Coldfield transmitter). If I connect several different units to a single unamplified feed, one at a time, the signal strength varies from about 10% to 40% between units. In all cases, I get a stable picture and 100% signal quality. 10% strength seems very weak to still get good reception. I presume that this is a bit of an underestimate, with some of the observed differences in the values due to the variability of the calibration.
 
Black Hole said:
From an engineering point of view, it would be sensible to make the 100% signal level the point at which the input saturated, but who knows.
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But that would vary between manufacturer/tuner type. An absolute signal strength in uV or whatever would be the ideal, but then would the percentage be linear or logarithmic?

Having said that, your idea also probably has more merit as 100% would possibly indicate that an attenuator is required, or that the noisy amp is not.
Do modern sig strength meters work the same way as older ones? i.e. stick a voltmeter across the RF negative feedback line, These were only ever meant as a comparison of signal strength of various stations on the same box and as such depend a lot on the gain of the RF front end circuitry which must be the same (or calibrated) before comparison between boxes can be truly relevant.
 
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My Panasonic TV shows a signal strength on BBC 2 of about 80%, implying the signal I am receiveing isn't too bad. (But I understand it is not a fair comparisson to use different devices made by different manufacturers.)

Neither the Humax or my TV show the signal in db, so not particularly helpful.
 
Percentages on signal strengths are completely and utterly pointless and meaningless. I don't know why manufacturers continue to label them so. Presumably to pander to this ignorance of most of the consumers, who have no idea of anything else.
 
Trev said:
But that would vary between manufacturer/tuner type. An absolute signal strength in uV or whatever would be the ideal, but then would the percentage be linear or logarithmic?
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How would that help, unless you also know what signal level is required for reliable reception?
 
So that people who know about these things could say 'That doesn't sound enough' rather than, as they do at present, 'The readings on the sig strength indication is pretty meaningless'
 
I would go for a system where whatever figure was given the upper and lower acceptable limits were also displayed (or made available to the user by some other means). I agree that the value probably comes from the AGC voltage, so it is crude at best, and the control voltage reaching its limits either way does not necessarily mean the input is unacceptable.
 
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