Had my Antiference distribution amp blow on Xmas day (poor timing) Replaced now with a Labgear version ...
Was thinking this over, I have no idea what strength signal is being received. If it is low I could then add a pre-amp, all I know currently without distribution amp (10dB gain) the HD channel break up, SD is OK.
It would be a waste to buy a UHF signal meter that may only ever be used once or twice ... then realised that 'maybe' there is an app for this for a Smart phone with a simple CT100 pass through pick up ...
TBH I found it more useful to use a signal strength calculator.
Start here to determine what transmitter and estimated signal strength
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If you are not in seriously dodgy territory you should be able to get by without gain
Remember it's not like the days of valves. Low noise front ends able to pick up and not add to whatever SNR is in the original signal are cheap and easy to put in any TV.
You should not have to boost HD mux. That suggests you may have a poor TV AND an aerial that is maybe not tuned to that mux.
With digital, there is no advantage to boosting beyond the point at which error correction gives you a 100% signal, anyway.
Many TVs, PVRs and STBs have a menu somewhere which displays signal strength and quality, either numerically or as an analogue bar. These allow you to see if one multiplex is weaker than another. You can't compare numbers (or the numbers that you estimate from an analogue bar) and say that one is twice as good as another because the number is twice as big, but you can at least say that one is bigger than other. I presume "signal quality" is based on bit error rate - ie how much the error-correction software is having to correct errors in the received signal.
Remember that multiplexes COM7 and COM8 (if your transmitter provides them - only the main ones do) are usually/always transmitted on lower power than many of the others, so will be weaker at the receiver. An aerial+amplifier than can receive the DVB-T (SD) and PSB3 (BBC/ITV HD) multiplexes might still struggle to get COM7/8.
Another site that I use for signal strength estimates is
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You can put in your postcode and then choose either the likeliest transmitter or force it to one specific one, and see the signal strength and the profile (whether there are any hills in the way).
Maybe Bill Wright will see this thread and be able to suggest what aerial and pre-amplifier is needed for a given signal strength as reported by this site, to determine whether your aerial is OK for the location, and whether a pre-amp is needed.
My experience where I am now (near Leyburn, getting signal from Bilsdale) is that a 4-port amplifier is needed for driving three devices (TV and PVR with daisy-chained aerial, and two DVB-USB adaptors for a PC), and that a pair of two-port passive splitters, cascaded, is not sufficient. Where we lived before, getting a stronger signal from Bilsdale and with a different aerial, the splitter solution was sufficient.
(Given that we have an unused output from the 4-port amplifier, maybe I should feed the TV and PVR from separate ports rather than daisy-chained from the same port. Not sure why I've only just thought of that!)
Beware also that some aerial leads are CRAP (to use a technical term). When we first moved in, I needed to extend the aerial cable to the other side of the room, and I temporarily used a 10 m cable that I happened to have. I found that it was very frequency-selective: I could receive some muxes and not others. The signal strength/quality indicators on the PVR and on my DVB-USB adaptors corresponded with this observation. Using a shorter length of cable, strengths were much more similar. I got my local TV shop to make up some proper leads from good-quality cable. Bill has some information about god/bad aerial cables on his web site. The crap one was much thinner diameter than any others, which probably affected its resistance, capacitance and hence impedance.
In addition, some receivers are more fussy than others. The PVR gives a lot more pixellation and picture breakup on COM7/8 than the TV or the DVB adaptors, even using the same port and the same cable. Actually, that PVR is probably destined for the bin because it's also started failing to record the whole programme or failing to start at all: sometimes it records for 3 hours when a 1 hour programme has been set, other times it records nothing.
Bill, what's your experience of Echostar PVRs? This is a Echostar HDT-610R-GB. It is significant that the support website myechostar.com/support has been hijacked by some Chinese spam site, which suggests that the company may have ceased trading.
If it isn't broke, don't fix it! All the channels are being messed around with over the next few years so I'd just sit and do nothing and see what happens.
The gain of a distribution amp does little more than compensate for cable losses.
Without taking actual measurements it's impossible to know just what you would need to do to increase the resilience of your set-up. However I'd guess that a low gain (9 or 12dB) masthead amp would be unlikely to do any harm and would very probably do some good, especially if the cable length from aerial to dist. amp. is significant. The masthead amp would have to be at the aerial of course. Don't use an amp with more than 12dB gain. Ideally, don't use one with adjustable gain.
I've never heard of such a thing. The 'simple pass through' would presumably need some sort of UHF detection.
I shouldn't take too much notice of the various signal strength predictors. They can only give a very approximate idea at best, and are often completely wrong. There's no substitute for an actual on-site measurement.
Noise from what? If you're using decent shielded cable that shouldn't be a problem.
Best to try another telly I guess. Although I've never come across one that is worse at reception than another. Poor reception is always a not good enough aerial, or too long a cable.
Satellite is easier. Since the box supplies 12V DC to power the LNB, you can get amps that fit inline anywhere on the cable that run off that 12V. I fitted a couple at my last place of work, where I'd had to run a Sky cable about 200 metres through the building.
Never heard of that, mind you the mobile phone signal around here is so f****ng pitiful it couldn't interfere with a fly. I often don't even get "3G" appearing on my phone, it just says "G" or even "E" whatever that is, along with 1 or 2 bars out of 6. It's good enough to usually hear 90% of the words the caller says, although occasionally it decides not to ring, then I get an answerphone message 10 minutes later. I'm in Central Scotland FFS, not the Outer Hebrides!
Broadcast TV signals are way too high frequency for a smartphone to do anything with.
Chinese signal strength meters are quite cheap. Good quality not at all, but can often get the job done. They don't of course give any clues about interference, multipath signals, signal versus frequency etc, but they will start by checking you've got a signal of about the right strength, and find out where in a system you're losing it.
I had one 6 years ago. Interesting design - a very small box only a couple of cm high. It had no fan. After 6 months the hard disk failed and I returned it to John Lewis. I seem to remember that before that it worked fairly well, but its tuner wasn't quite as good as the Panasonic TV's that I had at the time, as its "quality" readings used to vary rather a lot, while the Panasonic's readings were steady.
Oh dear. Even the first mobile phone signal were higher in frequency the broadcast tv, The problem lies from the probably lack of filters in the tv. High level mobile phone signals - froma nearby mast (for instance) can overload the front end of the tv set.
Anything the cable can pick up the aerial can pick up. But the aerial is designed to pick up and the cable is designed to not pick up so the aerial will pick up more. Sit on a roof in a city with an analyser and an aerial and you'd be surprised at the noise floor.
Yes. Before you look for 'more signal'. But see below.
I'd say a variation between TVs sets and between PVRs is the norm. Frequently customers say, "We have to watch some channels through the recorder because the telly is like the side of a container ship* on them channels."
*blocky.
Poor reception is always a not
The first thing a good aerial man will do when called to a telly with poor reception is check the signal levels. Quite often they are better than the TV set's reception is suggesting. It's a judgement call whether to increase signal levels or advise a new telly. With deaf tellys a simple set-back amp can be a cheap fix.
Since we do a lot of work in multi-occupier buildings we are very aware that residents' tellys are a factor when diagnosing poor reception.
Maybe I imagined it then. I'm off to get a drink now.
Shouldn't any noise be at a different frequency, so ignored by the receiver in the TV?
I'm glad that since digital was invented I've stuck mainly to dishes. Way less problems when you're only picking up from one very specific direction.
On a Sky box, it has two readings - "strength" and "quality". I assume noise puts the quality down but leaves the strength up.
You presumably live in a more built up area than me, where they've actually got enough mobile transmitters to be able to use mobiles properly. To make a call, you'll often see me waving the bloody thing around and standing on tall objects tying to get a lock first.
Noise can be at any frequency. Usually when there's a noisy background (if that's what I can call it) that could well emanate from a multiplicity of sources the noise power will be wideband. It won't necessarily be equal across any given frequency band, but it will normally be continuous across the band. This means that some of it will be within the bandwidth of the signal we are attempting to receive and decode. If we are very unlucky it will peak within the bandwidth of the signal.
A very small part of the noise floor is 'cosmic noise', about which we can do nothing.
Normally the biggest source of noise in a receiving system is the first active device the signal encounters in the system.
Remember that the level of the noise and the level of the signal aren't important; it's the ratio between the two that matters. Once that ratio is set no amount of amplification will improve reception.
Yes, I've always thought satellite was much easier than terrestrial.
Yes. Remember that the signal has already been amplified by about 50dB by the LNB, so the signal/noise ratio is set. The 'strength' reading is really not much more that a vague comment about the LNB gain and the length of the feeder cable.
Satellite receiver noise is not normally an issue. The LNB output is about 30dB above the point where receiver noise becomes important (feeder loss might be 10dB). By 'receiver noise' I mean the unavoidable noise generated in the tuner. A faulty PSU etc can generate a lot of noise.
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