Rusty Juggler Posted September 8, 2009 Share Posted September 8, 2009 (edited) This is a question directed at the pro- installers on this forum who may be able to share some thoughts. I am currently investigating possible upgrade paths of our Strata's ancient MATV system to allow reliable digital reception, my efforts through the years have earned me a position on the executive committee but that's about it. One of the things I've been looking at is the replacement of the wide-band headend with a channel based system. Currently, the only channel processing that takes place is the conversion of SBS Analogue from Ch28 to Ch0. The system is rather large (>80 units over several buildings) and a channel based headend seems more appropriate. With a background myself in the design and configuration of professional TV headends (in a previous life that is), I would like to know how good today's commercially available 'channel processors' work in the typical Metropolitan spectrum, with all its neighbour channels. All those years ago using channel amplifiers in such a scenario was an absolute no-no as it would destroy the group delay among other things. The answer was using frequency converters through IF (with SAW-filtering), a costly exercise (but not a major issue for professional systems). A survey has shown that a large majority of residents watches analogue TV and few of them have plans to upgrade to digital any time soon, which means that the headend will have to carry analogue as well as digital channels. Is this achievable with channel based technology and for a reasonable price? The next hurdle is to add SBS digital as the distribution network is not UHF capable. One option that springs to mind would be to convert Ch34 to a channel just above Ch12 allowing it to be distributed in VHF. A drawback could be that some receivers, potentially, ignore this frequency as it is not in the NIT (a few PC based receivers are known to suffer from this). Also, it may be illegal. Any comments are welcome. Cheers Rusty Edited September 8, 2009 by Rusty Juggler Link to comment Share on other sites More sharing options...
mtv Posted September 8, 2009 Share Posted September 8, 2009 Rusty, My first concern is that of the current distribution system not being capable of carrying UHF signals, as this may also be an indication the system will also have high BER and low MER, causing even digital VHF channels to be unreliable. Do you have any digital signal measurements, specifically BER/MER to judge how the system is/may perform/ing? Single channel amps available these days can cope with adjacent channels, but with two sets required for analogue and digital, it's a costly exercise. No doubt you've conveyed to the residents, the fact that analogue trasmissions are slated to cease, so it's false economy trying to incorporate analogue reception, when a 'digital-only' MATV distribution system will be half the cost and will function more efficiently with half the number of channel amps. Realistically, with the amount saved on a 'digital-only' system, would probably pay for a STB for those residents who currently do not own a digital tuner. The biggest hurdle as I mentioned, is the likelihood of poor digital signal reliability, if the cabling/taps/splitters/outlets aren't up to scratch and a 'bandaid' fix isn't going to help in the long term. Link to comment Share on other sites More sharing options...
ptt Posted September 8, 2009 Share Posted September 8, 2009 Agree with Col, there is no simple or cheap fix. I persume from your discussion that the building contains numerous units and that you have already seeked some advice? The issue with commercial distribution for DVB-T (even worse for DVB-S) is that you have to engineer and deploy the system with near Telco grade of service, ie less than 1 day outage/errors per year. With Analog you could get away with inferior systems, but with DVB-T the end user/service can very easily detect errors/problems. It is however well worth it when the right equipment and importantly, professionally qualified and experienced installer is used. The system operation will exceed 10 years. I cannot urge this enough as many strata bodies, etc, simply dont understand this. OK, to put this another way, lets say all the water coming into your units are dirtry after some years. Its been found that the galvanised pipe installed for distribution is leaking and rust is occuring in the water to the potable tap. Well, of course, you can see this easily and know that you must have water, and that the infrastructure will last a long time. So, eventually, you select a quality Plumber and a price, and then go about the installation. Not much is different with DVB-T (even S), problem is, you cant see the 'water'... Paul Link to comment Share on other sites More sharing options...
Rusty Juggler Posted September 8, 2009 Author Share Posted September 8, 2009 Thanks Col & Paul for your thoughts. Col, you hit the nail on the head, the only proper way forward is to start from scratch but the chances of getting this approved are slim. The system is your typical 30-year-old MATV that was poorly designed (if designed at all!) and has undergone several shoddy repairs over the years. One of the main concerns is the long underground cable runs between buildings that make UHF distribution doubtful. I have indeed done BER / MER tests throughout the property and the readings are poor to fair from the antenna down. One alternative solution I've been thinking of is to split up the system (7 buildings in total) and give each its own UHF only antenna (we have good coverage from the Manly translator in this area) as VHF reception is tricky due to the close proximity and varying directions to the transmitters. The end-networks need replacing anyway, they've been built with cable that looks like RG58 (!) and loop-thru wall plates. Cheers Rusty Link to comment Share on other sites More sharing options...
debruis Posted September 9, 2009 Share Posted September 9, 2009 Thanks Col & Paul for your thoughts.Col, you hit the nail on the head, the only proper way forward is to start from scratch but the chances of getting this approved are slim. The system is your typical 30-year-old MATV that was poorly designed (if designed at all!) and has undergone several shoddy repairs over the years. One of the main concerns is the long underground cable runs between buildings that make UHF distribution doubtful. I have indeed done BER / MER tests throughout the property and the readings are poor to fair from the antenna down. One alternative solution I've been thinking of is to split up the system (7 buildings in total) and give each its own UHF only antenna (we have good coverage from the Manly translator in this area) as VHF reception is tricky due to the close proximity and varying directions to the transmitters. The end-networks need replacing anyway, they've been built with cable that looks like RG58 (!) and loop-thru wall plates. Cheers Rusty I have just completed a MATV installation at a harbourside apartment block. I found that the strata management was unwilling at the time to upgrade the existing RG59 from their MSB where their main splitter was located to the wall outlets of each of the units. I suggested that they upgraded their antenna,distribution amplifier & splitters. Although the MER and BER readings were not ideal I have not heard a complaint from the building about the digital reception breaking up. I also told them I would not guarantee digital reception quality until they upgraded the cabling,wallplate and flylead. Maybe the gradually upgrade approach maybe the way to go. Get the body corporate to upgrade all the common area equipment where applicable and when individual owners are ready to connect they can get a contractor to replace cabling ,wall plate etc in their unit Regards Debruis Regards Debruis Link to comment Share on other sites More sharing options...
Biggs Posted September 9, 2009 Share Posted September 9, 2009 The end-networks need replacing anyway, they've been built with cable that looks like RG58 (!) and loop-thru wall plates.Cheers Rusty It'd be 59, maybe air space??? lol..Guess they just have to factor in the the cost to that sinking fund!. To OP--No offence but I get annoyed when I see BC skimp on what really needs re-investment to perform. Your asking a MATV installer to give you virtually the impossible IF you think your cable ---that's your first and last issue---will it last another 5 or 10 years???--Why even tempt fate---Rusty COFDM-PAL if your crazy enough to try on your NON- suitable UHF system..downconverted... . -Do bank on getting mutiple band aid calls for returns to patch and re-amplify and do loop da loops...I just don't like it sorry!..The costs associated with messing about and trying to fix unfixable problems could be better spent on new infrastructure. Link to comment Share on other sites More sharing options...
I am not a duck Posted September 9, 2009 Share Posted September 9, 2009 (edited) One alternative solution I've been thinking of is to split up the system (7 buildings in total) and give each its own UHF only antenna (we have good coverage from the Manly translator in this area) as VHF reception is tricky due to the close proximity and varying directions to the transmitters.The end-networks need replacing anyway, they've been built with cable that looks like RG58 (!) and loop-thru wall plates. I think that is the best way to go. It was an approach I adoptedsome time ago for a multi occupancy site with a similar set up. I don't recall the exact cable used, but it was RG59 dual shield air spaced with only 3 strands of braid and branded in yellow writing with "CATV-MATV CABLE". Luckily, by feeding the units at the mid point, with a fair amount of amplification, and replacing the loop through plates with drop taps, results were quite good. At the time, not many residents had digital TVs. Since Tassie is unique in that some services are only available on digital, this has hastened the uptake of digital receivers. EDIT: I remember, it was Channelmaster branded cable. Edited September 9, 2009 by M'bozo Link to comment Share on other sites More sharing options...
Rusty Juggler Posted September 9, 2009 Author Share Posted September 9, 2009 It'd be 59, maybe air space??? lol..Guess they just have to factor in the the cost to that sinking fund!. To OP--No offence but I get annoyed when I see BC skimp on what really needs re-investment to perform. Your asking a MATV installer to give you virtually the impossible IF you think your cable ---that's your first and last issue---will it last another 5 or 10 years???--Why even tempt fate---RustyCOFDM-PAL if your crazy enough to try on your NON- suitable UHF system..downconverted... . -Do bank on getting mutiple band aid calls for returns to patch and re-amplify and do loop da loops...I just don't like it sorry!..The costs associated with messing about and trying to fix unfixable problems could be better spent on new infrastructure. The cable type is thinner than RG59 and I've heard stories before about installers using 50 Ohm cable... As for implementing band aid solutions, I agree with your point of view however, at the same time I'm dealing with an owners corporation who, in large majority, do not see the benefit of spending money on something that isn't visible like new mail boxes or guttering. Cheers Rusty Link to comment Share on other sites More sharing options...
mtv Posted September 10, 2009 Share Posted September 10, 2009 I'm dealing with an owners corporation who, in large majority, do not see the benefit of spending money on something that isn't visible like new mail boxes or guttering. Perhaps it will only be when it's something they can't see... like TV, when analogue is gone, that they will understand the need for the upgrade. I've seen some very thin 75 ohm cable, similar to cheap flylead coax.... and it performs just as well.... very poorly! That cable and the use of loop-through wallplates will all but destroy DVB-T signals. Without the upgrading of the coax & outlets, it would be a total waste of money adding digital channel amps to the headend, as the end result would probably be no better than what they have now and they will be very unhappy with the cost involved, for little or no (digital reception) result. Rusty, I agree that separate antenna/cabling to each building is probably the best solution under the circumstances. Link to comment Share on other sites More sharing options...
ozdroggy01 Posted September 12, 2009 Share Posted September 12, 2009 G'day Rusty, First an apology for the long post but….. As a member of a residents committee in a retirement village of some 225 units I sympathise with your problem with the body corporate but envy you in only dealing with those of your own ilk rather than a financial conglomerate that is only interested in the bottom line. Like you our MATV system was hopelessly outdated and had grown in an uncontrolled way. Much of the cabling, even in the trunks, is RG59 air-spaced with some RG6 dual shield. There are isolated runs of RG11 in some parts of the trunks. There were shocking examples of bad connections; F-type connectors crimped with vice-grips, conductors and shields soldered and taped over to make a split, innumerable loose connections and corrosion in wall plates. All wall plates are loop-through PAL. We had been fighting with management over our problems for over three years before a proper attempt was made by a reputable specialist company to examine the problem and propose solutions. One of the requirements was to provide analog as well as digital signals because of the number of analog TVs [and incidentally VCRs] in use in the village. In hindsight it may have been better just to go digital and provide all who wanted them a STB but I am not sure how that would have satisfied the VCR requirement. At the heart of the matter was the distribution cabling and this was clearly recognized but, because of a total lack of diagrams and in the main the excessive cost of replacement, it was agreed to use the current cabling if possible. Once the headend was producing an output meeting the optimum standards of AS/NZS 1367:2007, critical cabling and hardware causing non-receipt of signals to units would be replaced. We embarked on a two stage approach. First the existing two antennas were replaced with commercial quality antennas specific to the digital bands; the height was also raised slightly and they were directed optimize the signal levels and picture quality from each. Second was to supply & install a COFDM digital to Analogue Processor that took the 5 best quality digital services and transfer them to analogue signals to replace the standard analogue channels 2, 7, 9, 10, 28. Concurrently install a channel processing headend to translate the current digital services to new channels whilst retaining the integrity of the digital service. The reasons for this were given as: 1. The COFDM to Pal converted signals will be the same programming as what is on the analogue channels with the benefit however of being digital quality (ie. No ghosting) 2. This 2 part process will allow both the digital and analogue channel frequencies to be pulled in closer together, reducing the system slope and minimizing the attenuation of the signals once they leave the headend by keeping the channel selection as low and compact as practical (higher frequencies = higher loss through the distribution cabling and greater spread of frequencies creates slope related issues throughout the system) The new system will also allow for the reticulation of digital services as the native digital format, allowing users the option of installing a set top box also if they wish. From previous experience of the contractor and readings taken at a number of unit outlets, it was anticipated that the changes to the headend would precipitate a large degree of compliance amongst the network and that remaining faults could generally be fixed in batches (e.g. the replacement of a single cable or amplifier would fix a ‘cluster’ of issues). After some initially poor performance in some clusters, this did in fact eventuate although there are still occasional glitches in the system which I believe will increase over time. Most units still have RG59 cable and PAL outlets. Although I have not been given the actual figures, based on early quotes, I believe the cost was in the order of $15,000 but I could be way out. It was management’s intention that eventually all cabling would be upgraded to AS/NZS 1367:2007 but as this will cost in the $100K area and as it has so far proved impracticable within budget to trace the cable runs I am not holding my breath. What I have been pushing for is that, whenever a unit is refurbished [generally at a cost of about $30000 +], the cabling and wallplates be replaced with RG6 quad, taps and F-type connectors. Currently we have a number of units under refurbishment with wiring over 15 years old and the old RG59 air spaced and loop-through PAL plates are being left in place ! To summarise. The phased approach has worked to a considerable degree - as Debruis has confirmed. Nevertheless our committee is still pursuing the real solution which will only be achieved when the distribution cabling is fully at AS/NZS 1367:2007 standard. If you would like to discuss further please send me a PM. Mike. Link to comment Share on other sites More sharing options...
Rusty Juggler Posted September 13, 2009 Author Share Posted September 13, 2009 Thanks for your 'essay' Mike, I must say that I've followed your 'adventures' through the years, and I do admire your attitude! For now, I shall stick to my position that the whole system will have to be replaced one way or another. Cheers Rusty Link to comment Share on other sites More sharing options...
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