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How do profesional riggers "point" an aerial.
From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. -- yours S Nihil curo de ista tua stulta superstitione |
soup wrote:
spelling police How do profesional riggers "point" an aerial. profesSional /spelling police -- e-crime and computer evidence conference 2005 - Coumbus Hotel, Monaco http://www.ecce-conference.com/ |
soup wrote:
From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. Cue Bill . .. . . . . . . . . Dave |
From here it is 226 degrees to the transmitter, if (when) I get the
"profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. Cue Bill . .. . . . . . . . . Dave Paul came in the other day, aghast. He had been approached on the street by another 'professional', an older man, who wanted to buy a few bits and pieces having been 'caught short'. Since Paul was just in the process of lifting his analyser out of the van the conversation had turned to test equipment. The experienced rigger advised Paul that the analyser was 'only a telly really, wiv knobs on, ain't it?' and that even an ordinary meter was unnecessary. Paul learnt from this meeting that the best way to do the job is to point the aerial in approximately the same direction as all the others, and then lie through your teeth about the poor reception until the customer paid up out of sheer boredom. So the answer to the original question is that the aerial rigging fraternity is in schism. On the one hand there is the high church orthodoxy of stalwart meter users, some of whom even make ostentatious use of analysers and other rigger's bling such as safety equipment and proper ladders. Some of these anally retentive people even have public liability insurance! On the other hand there is the Happy Clappy Church of Slapdapery, where test equipment is decried as pure unnecessary ostentation. The favourite hymn starts "If you're happy that you've botched it clap your hands!" In the Happy Clappy Church of Slapdapery each minister identifies a landmark within the diocese and decrees that all aerials should be pointed at it. This is usually a power station chimney (or something) in roughly the same direction as the transmitter, as viewed from the town centre. After all, Muslims only need an approximate idea of the direction of Mecca, so why should aerials need to be pointed more accurately? It's obvious, innit? In this day and age the church needs to attract young people, and they won't do that by imposing stupid rules like 'Thou must use a meter' and 'Thou must not rip off the customer' and 'Thou must not leave installations in a dangerous condition'. It's all so old fashioned and fuddy-duddy. Who cares in this day and age if an aerial falls on some old granny? And as for this controversy about rigger marriages! If one rigger really loves another rigger and they have a stable relationship why shouldn't the church consecrate their partnership? I hope this answers your question clearly and concisely, Original Poster. Bill |
"soup" wrote in message .uk...
From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. An amateur solution is to use a mobile phone (with free/ available minutes!) One person sits and watches the TV (i.e. daughter in my case) with one phone; me up ladder on my mobile (with hands-free) turning aerial. Daughter then changes channels and reports on quality of pictures. Only drawback is when she gets more interested in content than quality (i.e. strongest signal.) Before doing it, just check that the aerial cable is not live by some means or other... -esp. if using an aluminium ladder! Nick |
"soup" wrote in message . uk... From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. -- yours S Nihil curo de ista tua stulta superstitione I used a compass for the loft aerial, although it strikes me that the signal/quality meters in FTV box menus might give a better guide. Rob |
Before doing it, just check that the aerial cable is not live by some
means or other... -esp. if using an aluminium ladder! On that point, what is the power output of a masthead amp power supply..... ouch! ;) |
On Sun, 24 Oct 2004 08:33:20 GMT, "Mat Overton"
wrote: | Before doing it, just check that the aerial cable is not live by some | means or other... -esp. if using an aluminium ladder! | | On that point, what is the power output of a masthead amp power supply..... | ouch! Only 12 V which will not kill you from electric shock, only kills you if it makes you fall off a ladder. -- Dave F |
Angus Marshall popped their head over the parapet saw what was going on
and said soup wrote: spelling police How do profesional riggers "point" an aerial. profesSional /spelling police Typo (twice) rather than a spelling mistake, had looked it up in a dictionary and everything, won't happen again officer. -- yours S Nihil curo de ista tua stulta superstitione |
....and that was the abridged 'Readers Digest' version - the full version
can be bought at Waterstones and all other good bookshops. ;-) L3K |
In article , soup
says... From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. THey roughly point it in the same direction as the others. They then should attach a signal meter to it and move it until they get the best signal. -- Conor Opinions personal, facts suspect. |
In message , Dave Fawthrop
wrote On Sun, 24 Oct 2004 08:33:20 GMT, "Mat Overton" wrote: | Before doing it, just check that the aerial cable is not live by some | means or other... -esp. if using an aluminium ladder! | | On that point, what is the power output of a masthead amp power supply..... | ouch! Only 12 V which will not kill you from electric shock, only kills you if it makes you fall off a ladder. If you want to test for the 12V has reaching the aerial just stick your tongue across the terminals. If you don't fall off the roof then the power isn't reaching the masthead amplifier. -- Alan |
"Bill" wrote
| Paul came in the other day, aghast. He had been approached on the | street by another 'professional', an older man, Oh dear. | who wanted to buy a few bits and pieces Is that how he put it. | having been 'caught short'. Was that his excuse, he should have 'gone before he left home' | The experienced rigger advised Paul that the analyser was | 'only a telly really, wiv knobs on, ain't it?' and that | even an ordinary meter was unnecessary. There are some really, really, sick people out there aren't there. I hope Paul kicked him in the goolies and dialled 999. Owain |
"Linker3000" wrote
| ...and that was the abridged 'Readers Digest' version | - the full version can be bought at Waterstones and | all other good bookshops. Serialised monthly in a popular "Television" magazine Owain |
"Angus Marshall" wrote in message
... soup wrote: spelling police How do profesional riggers "point" an aerial. profesSional /spelling police a.k.a '******s' |
"soup" wrote in message . uk... From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. -- yours S Nihil curo de ista tua stulta superstitione I have seen it done three ways: 1) It was a very clear day and the transmitter could be seen by climbing up a little way; 2) Use of a signal meter, or 3) The aerial rigger told me that he had an internal transmitter detector in his head! All three resulted in the aerial being properly aligned! -- MESSAGE ENDS. John Porcella |
| Before doing it, just check that the aerial cable is not live by some
| means or other... -esp. if using an aluminium ladder! | | On that point, what is the power output of a masthead amp power supply..... | ouch! Only 12 V which will not kill you from electric shock, only kills you if it makes you fall off a ladder. Yes but the voltage isn't the issue, it's the wattage that hurts! |
Alan wrote in message ...
In message , Dave Fawthrop wrote On Sun, 24 Oct 2004 08:33:20 GMT, "Mat Overton" wrote: | Before doing it, just check that the aerial cable is not live by some | means or other... -esp. if using an aluminium ladder! | | On that point, what is the power output of a masthead amp power supply..... | ouch! Only 12 V which will not kill you from electric shock, only kills you if it makes you fall off a ladder. If you want to test for the 12V has reaching the aerial just stick your tongue across the terminals. If you don't fall off the roof then the power isn't reaching the masthead amplifier. A touch dangerous? The TV's I have come across do not have an earth connection, only live and neutral wires coming in. Hence, despite the aerial connection being separated by caps, the chassis tends to float to mid-rail (115V) unless connected to something else that is earthed, e.g. hifi system. Try an ac voltmeter between the aerial socket and earth (e.g. local radiator; water pipe, etc.) Current is very low, but you can still get a tingling feeling! |
wrote in message ... On 24 Oct, "harrogate2" wrote: In that case I'll keep away from you and your place if you don't mind. It is the CURRENT that hurts - 10mA will hurt, 30mA across the heart will kill. Skin resistance varies according to person, skin moisture level, etc etc. I once knew a chap who could get a minor shock off 24V, but for most people something rather higher - nearer four figures - is needed under normal circumstances. 50 volts can be enough to give you a big enough shock to lose concentration, and fall off a ladder. That will kill better than 30ma. Touche. -- Woody |
Nick Yarrow wrote:
"soup" wrote in message .uk... From here it is 226 degrees to the transmitter, if (when) I get the "profesionals" in will they point the aerial at 226 using a compass or do they have some sort of meter that measures maximum signal and they wiggle the aerial (after roughly aligning it either with a compass or even by just seeing what direction all the aerials about point) until they get a max signal. An amateur solution is to use a mobile phone (with free/ available minutes!) One person sits and watches the TV (i.e. daughter in my case) with one phone; me up ladder on my mobile (with hands-free) turning aerial. Daughter then changes channels and reports on quality of pictures. Only drawback is when she gets more interested in content than quality (i.e. strongest signal.) Simpler to take a TFT TV with you and rig it up so you can see it while wiggling the aerial. In the case of Freeview you may even be able to watch a signal strength bar while wiggling the aerial. -- Chris Green |
Simpler to take a TFT TV with you and rig it up so you can see it
while wiggling the aerial. In the case of Freeview you may even be able to watch a signal strength bar while wiggling the aerial. Sorry guys. I've been reading all this and I have to say that you can't align an aerial properly by looking at the picture on a TV set. For analogue the AGC hides most of the signal strength variations. If you really have to do this use an 18dB attenuator. The trouble then is that enough signal can enter the TV set directly to make your observations invalid. Aligning an aerial is about finding the position and orientation that gives the absolute best signal/noise ratio, even when lesser locations give an apparently perfect picture. Bill |
Bill wrote:
Simpler to take a TFT TV with you and rig it up so you can see it while wiggling the aerial. In the case of Freeview you may even be able to watch a signal strength bar while wiggling the aerial. Sorry guys. I've been reading all this and I have to say that you can't align an aerial properly by looking at the picture on a TV set. For analogue the AGC hides most of the signal strength variations. If you really have to do this use an 18dB attenuator. The trouble then is that enough signal can enter the TV set directly to make your observations invalid. Aligning an aerial is about finding the position and orientation that gives the absolute best signal/noise ratio, even when lesser locations give an apparently perfect picture. I did say (for FreeView) to "watch a signal strength bar". It may well not be quite so easy/quick/accurate as a signal strength meter but it certainly made the job possible for me. The Daewoo STB shows signal strength, S/N ratio and 'digital quality' (whatever that may be) on a single screen which makes watching what happens when you wiggle the aerial fairly easy to see. There doesn't seem to be much delay between moving the aerial and seeing any effect. As I'm only setting up the aerial for use with said Daewoo STB it matters not at all to me what the bars mean quantitively, as long as the Daewoo box thinks it's good then that's all I need. The only problem I found was optimising the aerial position across the different multiplexes and, unless you have several signal strength meters, I think that problem would be the same with a 'proper' meter. -- Chris Green |
I did say (for FreeView) to "watch a signal strength bar".
Oh yes, that's fair enough. You might find that an attenuator makes this easier, since the signal strength/quality bars are most likely compressed at the top, or don't register any difference at all above a certain level. I have seen some that go into the green with any signal from mediocre to massive. Bill |
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In message
Dave Fawthrop wrote: On 25 Oct 2004 11:42:44 GMT, o (Bill) wrote: | Aligning an aerial is about finding the position and orientation that | gives the absolute best signal/noise ratio, even when lesser locations | give an apparently perfect picture. Using equipment which we poor amateurs have not got and can not reasonably afford :-( Er, that's why you hire a professional to come and do it for you... -- Kevin Bracey, Principal Software Engineer Tematic Ltd Tel: +44 (0) 1223 503464 182-190 Newmarket Road Fax: +44 (0) 1728 727430 Cambridge, CB5 8HE, United Kingdom WWW: http://www.tematic.com/ |
On Mon, 25 Oct 2004 16:14:30 +0100, Kevin Bracey
wrote: | In message | Dave Fawthrop wrote: | | On 25 Oct 2004 11:42:44 GMT, o (Bill) wrote: | | | Aligning an aerial is about finding the position and orientation that | | gives the absolute best signal/noise ratio, even when lesser locations | | give an apparently perfect picture. | | Using equipment which we poor amateurs have not got and can not reasonably | afford :-( | | Er, that's why you hire a professional to come and do it for you... But professionals cost *money* :-( -- Dave F |
On Mon, 25 Oct 2004 19:01:46 +0100, Dave Fawthrop wrote:
On Mon, 25 Oct 2004 16:14:30 +0100, Kevin Bracey wrote: | In message | Dave Fawthrop wrote: | | On 25 Oct 2004 11:42:44 GMT, o (Bill) wrote: | | | Aligning an aerial is about finding the position and orientation that | | gives the absolute best signal/noise ratio, even when lesser locations | | give an apparently perfect picture. | | Using equipment which we poor amateurs have not got and can not reasonably | afford :-( | | Er, that's why you hire a professional to come and do it for you... But professionals cost *money* :-( And you may well get a cowboy ;-( -- Phil Cook looking north over the park to the "Westminster Gasworks" |
Phil Cook wrote:
On Mon, 25 Oct 2004 19:01:46 +0100, Dave Fawthrop wrote: On Mon, 25 Oct 2004 16:14:30 +0100, Kevin Bracey wrote: | In message | Dave Fawthrop wrote: | | On 25 Oct 2004 11:42:44 GMT, o (Bill) wrote: | | | Aligning an aerial is about finding the position and orientation that | | gives the absolute best signal/noise ratio, even when lesser locations | | give an apparently perfect picture. | | Using equipment which we poor amateurs have not got and can not reasonably | afford :-( | | Er, that's why you hire a professional to come and do it for you... But professionals cost *money* :-( And you may well get a cowboy ;-( Watch out. I'm rapidly trying to reduce personal weight so that I can safely climb peoples roofs. Is there a CAI recommended guideline on this. What should I aim for? 10 Stone? :-) -- Adrian C |
"harrogate2" wrote in message ... "Mat Overton" wrote in message o.uk... | Before doing it, just check that the aerial cable is not live by some | means or other... -esp. if using an aluminium ladder! | | On that point, what is the power output of a masthead amp power supply..... | ouch! Only 12 V which will not kill you from electric shock, only kills you if it makes you fall off a ladder. Yes but the voltage isn't the issue, it's the wattage that hurts! In that case I'll keep away from you and your place if you don't mind. It is the CURRENT that hurts - 10mA will hurt, 30mA across the heart will kill. Skin resistance varies according to person, skin moisture level, etc etc. I once knew a chap who could get a minor shock off 24V, but for most people something rather higher - nearer four figures - is needed under normal circumstances. -- Woody Out of interest, you have just made the point that it is the wattage that matters! You can't get the amps without the volts. (Ohm's Law) Rickey |
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"Phil Cook" wrote in message ... And you may well get a cowboy ;-( -- And don't you just..... The "recommended" outfit that fitted my new " digital" aerial dropped the lead-in over the roof, over the gutter and down the wall - and about the only place they used a cable clip was straight into the lead flashing that's supposed to keep the water out of my single storey extension. Doncha just love 'em? Chas |
On Mon, 25 Oct 2004 21:18:30 +0100, Alan
wrote: | In message , wrote | | | The only problem I found was optimising the aerial position across the | different multiplexes and, unless you have several signal strength | meters, I think that problem would be the same with a 'proper' meter. | | | Didn't you find the screen that shows all signal strengths and signal to | noise figures for all MUXs on the same screen? Non of my three STBs have such a screen. :-( -- Dave F |
Alan wrote:
In message , wrote The only problem I found was optimising the aerial position across the different multiplexes and, unless you have several signal strength meters, I think that problem would be the same with a 'proper' meter. Didn't you find the screen that shows all signal strengths and signal to noise figures for all MUXs on the same screen? Maybe I did, I can't quite remember. There isn't a screen that shows all three paramters for all MUXes is there though? -- Chris Green |
The only problem I found was optimising the aerial position across the
different multiplexes and, unless you have several signal strength meters, I think that problem would be the same with a 'proper' meter. That's just one reason why a spectrum analyser can be handy. It can be fascinating to watch the various channels as they are affected by, say, reflections from an aeroplane or propagation anomalies. Having said that, it is really quite unusual to have different optimum positions for each channel. When that does happen it normally means that even the 'optimum' positions are actually a long way from being really good positions. What I mean is, the 'optimum' positions are probably 15 to 20dB below what they would be if the aerial wasn't badly screened by buildings, trees, or hills. You need to be maybe 15dB below the line-of-sight figure for the effects of screening to start giving significantly odd results, like different maxima for different channels. This often means that reception will be unreliable or even permanently poor. Maybe you can't do anything about it, but maybe you can by spending a bit of time or money. If you are getting different maxima in the loft, you really should try to get the aerial outside.Otherwise, accept that you're doing a severely compromised job. Normally, if you align the aerial for the weakest mux the others will be optimised as well. Incidentally, the beamwidth of a yagi is usually a bit narrower if anything towards the top end of the frequencies it covers, and since the higher channels also tend to suffer more from screening, if all else is equal use a higher channel to align the aerial. Sorry this reply is a bit disjointed, but the cat wants me to groom him and is nudging my hands as I type. I'll disjoint him if he doesn't behave! Bill |
Bill wrote:
Having said that, it is really quite unusual to have different optimum positions for each channel. When that does happen it normally means that even the 'optimum' positions are actually a long way from being really good positions. What I mean is, the 'optimum' positions are probably 15 to 20dB below what they would be if the aerial wasn't badly screened by buildings, trees, or hills. You need to be maybe 15dB below the line-of-sight figure for the effects of screening to start giving significantly odd results, like different maxima for different channels. This often means that reception will be unreliable or even permanently poor. Maybe you can't do anything about it, but maybe you can by spending a bit of time or money. If you are getting different maxima in the loft, you really should try to get the aerial outside.Otherwise, accept that you're doing a severely compromised job. I know it's a compromise but since it works OK now that's good enough. Putting the aerial outside (as I have explained in posts quite a while ago) would be a real pig to do. Normally, if you align the aerial for the weakest mux the others will be optimised as well. Incidentally, the beamwidth of a yagi is usually a bit narrower if anything towards the top end of the frequencies it covers, and since the higher channels also tend to suffer more from screening, if all else is equal use a higher channel to align the aerial. I think I ended up realising this, one of the MUXs here is a lot higher in frequency than all the others and if that works OK they usually all do. The only oddity I have is that there appears to be a reflection or standing wave or some such which affects the BBC1 MUX and the best position for all the other MUXs drops BBC1 into a trough. It just need the aerial dropeed a few inches to sort this though and that didn't have a big effect on the other signals. Sorry this reply is a bit disjointed, but the cat wants me to groom him and is nudging my hands as I type. I'll disjoint him if he doesn't behave! Strangely our cats don't disturb me when I'm typing here, they sit on my chest in bed and on my lap at breakfast. -- Chris Green |
On Sun, 24 Oct 2004 21:53:56 GMT, harrogate2
wrote: It is the CURRENT that hurts - 10mA will hurt, 30mA across the heart will kill. Question: So how do 30mA trips save you then? Answer: Time is a relevant factor as well as current. 30mA for 30ms should trigger the trip. |
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