Wireless Waffle - A whole spectrum of radio related rubbish
How Not To Install A Satellite Dish (Part II)signal strength
Saturday 16 May, 2015, 15:38 - Satellites, Much Ado About Nothing
Posted by Administrator
In the last instalment of 'How Not To Install A Satellite Dish', we successfully installed and aligned a new satellite dish to point at 19.2 degrees East so as to be able to receive German language television (and a few French channels to boot). The next job was therefore to connect the new dish, and the old dish, to the satellite receiver so that the same receiver could be used to switch between the German channels and the English language channels received through the existing, and separate, dish pointing at 28.2 degrees East.

Thankfully this does not (should not!) require the fitting of an additional downlead from the dish to the receiver, oh no. A system called DiSEqC (apparently pronounced 'die-seck' though in reality it should be pronounced 'diss-equck') comes to the rescue. This allows the receiver to select from multiple dishes connected on the same cable by sending control signals along the cable. All that is required is that a suitable DiSEqC switch is installed at the satellite end, connected to both dishes, and to the cable from the receiver.

2 way sat switchA 2 way sat-switch was duly purchased and installed as per the instructions. Back at the receiver (a trusty Foxsat HDR - though the original model, not the new one being sold now on Amazon), the secret menu that allows access to funky multi-satellite functions was accessed (by going into the Setup menu, then pressing red, green, yellow, blue, green, yellow and then blue in that order - or 🌑🌑🌑🌑🌑🌑🌑). Selecting 'DiSEqC 1' from the pull-down menu duly yielded signals from the original 28.2E dish. However, none of the other four DiSEqC inputs yielded anything from the 19.2E dish. Swapping the feeds at the dish end meant that channels from the 19.2E dish could be found on 'DiSEqC 1' but no signals from the 28.2E dish could be found on any setting. Grrr...

4 way sat switchThe DiSEqC settings in the receiver had four channels (e.g. 1, 2, 3 and 4) but the switch only had two. Could this be the problem? Only one way to find out, and so a second switch, this time a 4 way sat-switch was bought (which oddly is cheaper than the 2 way switch at the time of writing!) The original (28.2E) dish was duly connected to input 1 on the switch and the new 19.2E dish was connected to input 2. And guess what - this time success. Now the receiver would find signals from both satellites on the appropriate DiSEqC settings on the receiver.

It is unclear whether this was due to the fact that the first switch was faulty, but as the 4-way switch is (currently) cheaper than the 2-way switch, then anyone attempting this exercise might like to consider just getting the 4-way device to start with and thereby circumventing the tedious hours of failure that might otherwise present themselves.

freesat foxsat menuAnd so now, by switching the Foxsat receiver out of 'Freesat' mode, it was possible to access a wide range of German channels (and the UK ones) but without the help of the Freesat programme guide. Switching back to Freesat mode returned the box to the standard Freesat channel line-up and the programme guide. But surely there must be a way to add the German channels to the Freesat channel menu so that there's no need to go faffing around with multicoloured buttons in the settings menu to switch between them? Actually, there is and at least that part of the job went relatively easily, so stay tuned to Wireless Waffle for Part III of 'How Not To Install A Satellite Dish'...
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How Not To Install A Satellite Dish (Part I)signal strength
Tuesday 31 March, 2015, 04:51 - Radio Randomness, Satellites, Much Ado About Nothing
Posted by Administrator
It's been a long while since anyone at Wireless Waffle installed any satellite dishes, however as part of a project to improve language skills, it was decided that the WW HQ would be fitted with the kit needed to receive German television. This is the sad story of the trials and tribulations of what should have been a simple job in the hope that it may help others trying the same thing not to fall into the same traps that befell our attempts!

Firstly, a visit to Lyngsat and a browse through the dozens of satellites that cover Europe quickly yielded the fact that the channels that were wanted could be found on various Astra 1 satellites at an orbital position of 19.2 degrees East (19.2E). As a ready reckoner, the following orbital positions are the 'hot-slots' for various European languages:
  • English - 28.2E
  • French - 5W
  • German - 19.2E
  • Italian - 5W or 13E
  • Polish - 13E

astra 1m footprintThe next thing to do is find out what size of dish is needed to receive the satellite that's of interest. This is more complex as it requires a knowledge of the satellite's footprint and the strength of signal at a particular location. For 19.2E in the UK, even a 55cm dish should be fine pretty much everywhere, so a Triax 54cm dish was duly purchased together with a suitable wall bracket and an Inverto LNB.

The mounting of the dish on the wall was relatively straightforward, having made sure that there were no obstructions in the line-of-sight from the dish to the satellite (such as trees or other buildings). With the dish on the wall, the next step is to align it so that it is pointing at the satellite. In general a rough idea of the right direction can be gathered if you know your latitude and longitude and the satellite you wish to receive through many online tools (such as dishpointer.com).

Getting the dish pointing in roughly the right direction is not too difficult, but even a small dish needs to be pointing with an accuracy of better than plus or minus 1 degree (bigger dishes have to be even more accurately aligned) and so some form of fine tuning is needed.

In analogue days gone past, by far the best way to align a dish was to connect it to a satellite receiver, and connect the satellite receiver to a television, and put the whole lot in a place where the TV could be seen from the dish. With the satellite receiver tuned to a channel on the appropriate satellite, it was then just a matter of moving the dish about until a signal could be seen on the TV. Once the signal was found, gently moving the dish from side-to-side and up-and-down to a point where the quality of the picture was maximised was all that was needed. Of course the same method can still be used today, but there has to be a less crude way, right? Right...

slx satfinderThe SLX Satellite Finder costs less than a few metres of CT-100 coax, and provides both a visual indication of signal strength (using the in-built meter) and an audible indication (using the in-built buzzer). All that is then required to use this to align a dish is a 'patch lead' so that the dish can be connected to a socket on the meter and then a lead coming from the (indoor) satellite receiver connected to the other socket on the meter to supply power. So far, so good.

Now, turn on the satellite receiver and return to the dish. In theory, the meter should only register a signal if the dish is pointing at a satellite. However, the modern Inverto LNB was obviously doing a far better job of receiving than the systems that the crusty SLX meter was being designed to work with resulting in a full-scale meter deflection (and an annoying beep that could not be turned off) almost regardless of the position of the dish. No amount of experimentation yielded anything other than full-strength or nothing, and the full-strength indication happened across a wide arc of the sky and with the elevation angle of the dish anything within 10 degrees of that which should have been right. In a word, beeping useless!

sf 95dr satfinderNot to be defeated, and rather than cart the TV and receiver outdoors, a second, seemingly more modern meter was purchased, the SF-95DR Satellite Finder. This proved to be marginally better, but having the dish within 'a few' degrees of the right position still yielded a full-scale signal. At least the beep could be turned off.

An old trick from the analogue days to reduce the signal to make fine tuning the position of the dish easier if the signal was very strong, was to cover the dish in a damp tea-towel. The water in the towel will attenuate the signal making the signal weaker and thus the dish easier to align. This trick was tried using the SF-95DR but alas, only resulted in the need to keep picking up a damp tea-towel from the floor, every time the wind blew it off.

Eventually, more through luck than skill, a point was found where the meter indicated a peak that was within a degree or so of nothingness in nearby directions, suggesting that the dish was aligned to a satellite. An excited scan of the receiver revealed some signals but alas, from the wrong satellite (13 East instead of 19.2 East). Of course the meter would no more know which satellite it was pointing at than an amoeba would know the difference between a car and a lorry, just that both seem pretty big. More fiddling, and a slightly damper tea-towel and a second 'peak' was found. Another tune of the receiver and 'Allelujah!' channels that were being transmitted from 19.2 East were found. But only from one transponder...

dish alignment girlWhat could this mean? Was it that the dish was roughly aligned but that only the very strongest signal was being received? Was it that the LNB was faulty? Was there a fault in the cable from the dish to the receiver indoors? Any (or all) of these could be the problem and with nothing more to go on, it seemed that the only way to resolve the issue was to resort to carting the TV and receiver outdoors so that the screen could be seen from the location of the dish. Doing this would mean that the 'signal strength' and 'quality' bars on the receiver's on-screen menu display could be used to point the dish more accurately.

A new patch lead from the dish to the receiver was fitted with F-connectors (thereby ruling out any problem with the coax feeding indoors). Power up... And the receiver is showing 100% signal strength (very good!) but a signal quality of only 60% (OK but not brilliant). No amount of dish repositioning would yield any improvement and still just the one transponder was receiveable. Before giving up and ordering a new LNB, and with an increasing level of suspicion building up, the meter was taken out of line so that the dish was connected directly to the receiver without the meter in circuit.

Hey presto...! Now the receiver was showing 100% signal and 80% quality and, wait for it, all of the transponders on the satellite could be received. A final fine-tune of the dish position and the quality of reception was increased to 90% - not a bad result at all. Moving the TV and receiver back indoors to the other end of the original run of coax and this excellent result was maintained. It seems that the meter may have been overloaded by the signal from the satellite and was somehow distorting the signal (possibly it was generating harmonics or intermodulation products).

So the lessons from this cautionary tale are:
  • Don't use cheap 'satellite finder' meters to help align dishes, they cause more problems than they solve.
  • Stick to the tried and tested methods and just move a TV and receiver to a place where they can be seen from the dish and use the receiver's signal meter for alignment.
  • Damp tea-towels should be used for wiping down surfaces in kitchens and not for the setting-up of sensitive electronic equipment.

At this point you're probably thinking that this is the end of this cautionary tale, but you'd be wrong... there's more to come! Stay tuned to Wireless Waffle for our next extremely uninspiring episode of: HOW NOT TO INSTALL A DISH.
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Nuff sed...?signal strength
Friday 27 February, 2015, 15:09 - Spectrum Management, Much Ado About Nothing
Posted by Administrator
Experts at the University of Surrey have allegedly achieved wireless data transfer speeds of 1Tbps (Terabits per second), albeit in laboratory conditions and over a distance of just 100 metres. Sizzle! Then again, just imagine the cost of rolling out the 10 million or so cell sites that would be needed to cover the UK. Ow! Nonetheless this is a significant achievement. Yay!

1tbps zoom zoom

Mobile data connections working this fast would be able to transfer the contents of a blu-ray disk (typically 50 GigaBytes) in just under half a second. Wow! At typical current average mobile internet tariffs, the cost of transferring the data for the blu-ray would be around GBP200. Wowzer! Assuming you wanted to do this every day, the monthly cost of your mobile contract would be around GBP6000. Zowee!

Do we really need to say any more?
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Why-Fi No-Fly Zonesignal strength
Friday 7 November, 2014, 17:20 - Spectrum Management, Much Ado About Nothing
Posted by Administrator
Various news web-site including CNN and the BBC report that American Airlines flight 136 due to fly from Los Angeles to London on October 26 was delayed by almost a day when a passenger sitting on the aircraft noticed a WiFi network named 'Al-Quida Free Terror Nettwork'. As a result, the aircraft was emptied and a search conducted by US Customs and Border protection officials but the source of the offending WiFi signal was never found. No doubt the misspelling of 'Al Qaeda' and 'Network' enhanced the level of terror indicating, as it does, that the person who set up the network was potentially:
  • someone for whom English was not their first language;
  • a dimwit whose IQ was far below average;
  • someone with scant regard for spelling in an infidel's tongue; or
  • a person deliberately trying to mask their true intentions by appearing as one of the above.
Any of the cases above would no doubt strengthen a belief that the network was established by a terrorist group to whom any and all of those characteristics could apply.

As the BBC notes:
Many broadband subscribers re-name their home wi-fi network to personalise it.

ideal cleaning wirelessBack in 2007, Wireless Waffle undertook a survey of WiFi channel usage which found networks with such kooky names as 'Gary Barlow', 'Slapheads Network', 'Toast' and 'Fraudulent'. The practice of personalising WiFi network names (or SSIDs as they're technically known) is not a new one and whilst naming a network after a terrorist organisation is clearly a very bad idea (especially whilst at an airport) there's no law against it. If just setting an SSID to such a name can disrupt flights at a busy airport, then it opens the door to widespread misuse of, for example, the WiFi tethering options on mobile phones, to conduct all kind of Rabelaisian ruses.

Many airports and other major venues and events (such as at the London Olympic Games) use radio spectrum monitoring equipment to check for people using unlicensed frequencies as the wireless landscape in such places is very complex with many networks sharing neighbouring frequencies. Careful planning is essential to ensure that the myriad of users do not interfere with each other (especially to the safety critical air-ground systems for example) and monitoring is vital in keeping the airwaves free of signals that could cause problems.

Maybe airports and other establishments that might be the target of people intent on causing havoc with their naughtily named WiFi SSIDs could take a leaf out of the book of Marriott and also install WiFi monitoring systems that would allow naughty network names to be traced and closed down before they caused multifarious mayhem.
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