HF Radio Fund:

Projects :: Me on QRZ :: HF Radio Fund: £35 of £500: 7% funded

Friday, 6 March 2015

"Seeing Circles, Sines and Signals" - a DSP primer

Not had a detailed read through it yet, but this seems to be a very well-written visual approach to DFT and digital signal processing in general.

Here's the link.

(Also, I've now finished the last M0 lesson and am about to begin on the next!)

Tuesday, 24 February 2015

My Thoughts on Anytonetech

So Brick and Hans have posted their opinions on the new Anytonetech announcement, so I think it's appropriate I follow suit, seeing as I've been very vocally critical of it elsewhere.

A big hoo-ha was made about it; and a lot of buzz was generated on the Internet about BaofengTech's new announcement. It didn't take me long to clock on to what the announcement was.

Many folks, including myself, were hyped for seeing a new Baofeng radio; alas, it didn't happen. I'm not even mad about this. More choice in the world of handheld radios is a good thing.

What irks me is the fact that this announcement was literally nothing but a marketing exercise. Having media media qualifications and work experience under my belt, I can see through the announcement for exactly what it is. The radios Anytonetech are branding as the next big thing in Chinese handhelds have already existed and been on sale for months.

What Anytonetech are doing is simply sticking their own names on the Anytone AT-398UV and AT-288 radios, using the "R" prefix used by Baofeng and misrepresenting them as related to the originals, and they will probably flog them at a significant margin. Why can't they just be honest and sell them as they are? You want an "Anytonetech TERMN8R"? Go buy a frigging AT-398UV! It's THE SAME RADIO! Jeez louise. It even has JTAG pads on the board for firmware upgrading. You can disable the VFO to make it Business Radio compliant. It receives shortwave. And so on.

On top of this, a lot of people still think these are new Baofeng radios. They're not! Let me say this again. They are Anytone radios. Made by Anytone. That already exist and are sold by Anytone on their Aliexpress store.

There is a worrying lack of innovation happening in the U/V HT world at the moment. Anytone, Baofeng, Wouxun, and friends: go and read blogs and the comments. People don't want yet another Yaesu Vertex clone. They want innovation, and innovation that is not even difficult to implement.

This is why, unless something changes soon, then an OSHW handheld U/V radio might be on the cards. If Corporate China won't innovate, we will.

Watch this space.




The Last Leg: Zero to M0: Part Three: The *other* LCRs

Welcome to part three of this epic quest through the Advanced syllabus. I'm currently waiting for my copy of Advance! to turn up as yet, so expect corrections when it does arrive.

Now we start getting very technical. And this is the easy stuff. So hold on...

L, C and R are the reference designators for, respectively, inductors, capacitors and resistors. These alone are the building blocks for pretty much every RF circuit in existence: if you had an unlimited supply of all these components - along with the humble transistor, but more on that in a latter writeup - you could build literally any radio transmitter or reciever you wanted. It would be tedious, but it could be done.

When you combine these, they do various things to a signal you pump into them. Let's go over what's what:
  • An Inductor (L, which stands for "(Heinrich) Lenz", the discoverer of inductance) blocks alternating-current (AC) signals at the inductor's resonant frequency while passing DC. You see large inductors in power supplies for the purposes of eliminating ripple and noise. The unit of measurement is the Henry (H).
  • A capacitor (C) blocks DC while passing AC at the capacitor's resonant frequency. It can store a charge across its plates (terminals) and is often used to stabilise (or smooth) transients by "shunting" any variation in the supply voltage to ground. The unit of measurement is the Farad (F).
  • A resistor blocks both AC and DC linearly (i.e., by the same amount at all frequencies). Resistance is measured in Ohms (Ω). You'll have noticed that the inductor and capacitor are the inverse of each other: the resistor, which has resistance in Ohms, has an inverse too: the transistor, which amplifies both AC and DC linearly and has transconductance measured in Siemens (S). Going further, AC resistance and transconductance that changes with frequency is called impedance and admittance respectively.
If you're confused about resonant frequencies, I'm going to cover those in the next post, but suffice to say it's the frequency at which the component works "best".
We should probably recap here, since you'll be using these symbols a LOT later on:

Property of..
Measured in
Symbol in equations
Inductancean InductorHenries (H)L
Capacitancea CapacitorFarads (F)C
Resistance
a Resistor
Ohms (Ω)R
Transconductance or Gaina Transistor or ValveSiemens (S)
β or gM
Impedance (frequency dependent resistance)VariousOhms (Ω)Z
Admittance (frequency dependent transconductance or gain)VariousSiemens (S)Y

The simplest of these is probably resistance. No doubt at this level, you have already encountered resistance, so I won't go into too much detail here. But you should at least be able to recall that resistance:
  • is opposition to the flow of free electrons round a circuit
  • dissipates current (and therefore power as heat) across itself according to the formula I = V/R
  • works equally at all frequencies, from DC (f0 = 0Hz) through all AC frequencies to daylight
  • works equally at all voltages
and that resistors have a positive temperature coefficient; that is, that their resistance increases with heat.

You will also need to know how to calculate parallel and series resistances:


To calculate series resistance, simply add them together.

RTotal = R1 + R2 + R3



Calculating parallel resistance is a bit more challenging. Other folk often give this in fractions, as does the formula sheet you get at the exam:



But if your maths isn't that hot, calculating the reciprocal on a calculator is a bit... huh? Where's the "1 over" button?

Nine times out of ten, there isn't one. Rather than using the above, you would enter it in the calculator as



It's actually exactly the same calculation, just in a form a bit easier to enter into a calculator :)

You should also know how to formulate a resistive divider, which allows you to reduce an input voltage by the ratio between two resistors, shunting the "unused" voltage to ground:

Resistive Divider



Inductance is calculated the same way as resistance. Simply substitute R for L.

Series:





Parallel:



 

Calculating series and parallel capacitance is simply a matter of swapping over the sum and reciprocal. If you think about it, this makes sense: essentially, with capacitors in parallel, you are simply making the "plates" of the capacitor bigger, increasing the "capacity" of the capacitor bank.

So for capacitors, the formulae are:

Series



 

Parallel




You may be thinking to yourself: these values can't just be arbitrary, can they? You know, if you're making a capacitor that is 2200uF or a 100nH inductor, there has to be some way they can work out the dimensions and characteristics for a given value. And you'd be right.

For inductors, there are many factors: the gauge of the wire. the spacing between the turns, the magnetic permittivity of the former and so on. So many factors, in fact, it's not tested in the exam, and this is left as an exercise for the reader.

You are however tested on how to calculate capacitance: this is simple by comparison. All you need to know are two three things:
  • The dielectric constant (K).
  • The area of the plates (A).
  • The distance between the plates (d).
Recall that a capacitor is simply a pair of electrodes (plates) separated by an insulating material called a dielectric. K is calculated by taking the dielectric permittivity (or "charge-holding ability", in layman’s terms) of free space, or in other words a vacuum, and multiplying it by the dielectric permittivity of the insulating material.

The dielectric permittivity of free space, with the symbol ε0, is 8.854 x 10-12 F/m, with farads per meter (F/m) being the measure of dielectric permittivity.

The electrolyte in an electrolytic capacitor often uses ethylene glycol as a base, which has a relative permittivity (εr) of 37 F/m. Wikipedia has a list of materials and their relative permittivities here. So you would simply multiply ε0 and εr,  and you have your K.

The formula for actually turning this into a capacitance, is
 

Thankfully, you are only expected to be able to recognise the formula on sight and not apply it; but if you, say, are building a magnetic loop and are building your own capacitors, this formula could save your bacon!

So that's it for this time. This was a brutal post to write, mostly thanks in part to the fact this is basic school-level stuff and hence tedious to write. But it's fundamental to the rest of the exam, so it's need-to-know. If you don't, much of the rest of this lot won't make sense!

Interesting things happen when you combine capacitors, inductors, and resistors, and that's the theme for the next post.

Edit: my copy of Advance! showed up, so here goes! Note that Codecogs is currently broken and as such no equations will display right now.

The value of the capacitor is also a measure of how much charge it will hold at a given voltage. The formula for this is:

C = Q/V

where C is the capacitance (in Farad), Q is the charge held by the plates (measured in Couloumbs and V is the potential difference (voltage) applied across the plates. The capacitance is determined not by Q and V but rather this is for deriving Q from C & V.

A capacitor of 1 farad will store 1 couloumb of charge for an applied voltage of 1V.

Different types of dielectrics


  • Paper capacitors are often very large with high capacitances and a high flashover voltage.
  • Polythene & polypropylene capacitors are plastic dielectics. They can withstand even higher voltages than paper dielectrics, but they are lossy due to absorption of charge into the dielectric itself, which is dissipated as heat. The losses increase with frequency, so they are unsuitable for VHF and up.
  • Polystyrene, PTFE and mylar dielectrics are more stable & less lossy. But also far more expensive.
  • Ceramic capacitors have relatively low loss and are cheap, making them ideal as a balanced option for RF use. They can have a variety of dielectrics, as Wikipedia points out (see image above).
  • Mica is a very low loss ceramic dielectric, but it's expensive (for a reason).
  • Air is used as the dielectric in a variable capacitor: turning the shaft increases the overlapping plate area and hence the capacitance.
  • Electrolytic capacitors use aluminium foil one one plate and a conductive paste on the other; due to this imbalance between plates they are said to be polarised and must be connected the right way round.
As a capacitor charges, the amount of current it draws off the supply will decrease as the potential difference between the plates increases. The time taken for the voltage to reach 2/3 through a given load (resistance) is known as the RC time constant  and can be figured out using the formula

τC = RC

hence the name.After approximately 5τ seconds the capacitor is pretty much fully charged, but due to the law of diminishing returns that applies to capacitor charging it can never be fully charged. Remember that the current that is charging the capacitor decreases as time goes on!

Inductors work by storing a magnetic field in the coil. As this magnetic field increases, the potential difference across it decreases - Lenz's back EMF phenomenon - whilst the amount of current flowing through it increases. Like many things about inductors, they are inverse with respect to capacitors. 

So no prizes for guessing the inductive time constant, the time the inductor takes to build up its local magnetic field to maximum...

τL = R/L

Saturday, 21 February 2015

A Post About LCRs

Wrong LCRs. I know the next tutorial part on passives is due but I simply haven't had the time. But no. This is about Little Chinese Radios.

Love them or hate them, they're here to stay. This post is about three of them in particular; a mini-review from someone who's used them as primary radios for some length of time, if you will. If you're new to amateur radio, or radio at all, you're very likely to have used one of these; in addition, I'm going to review the cheap piece of hardware that got me into this hobby again in the first place.

If you're considering buying one of these, all but the last item require a licence to use pretty much anywhere in the world. Do not transmit without one!

The Baofeng UV-B5


This was my first radio and to this day remains the one I recommend to everyone starting out in the world of amateur radio. For £21 shipped from China direct, it really cannot be beaten for value for money.

There is a B6 variant as well with a flashlight instead of a rotary dial, but I had an inkling I would prefer the rotary dial on top instead. I was right.

So how does it fare?

Well, I never actually got a chance to test it on the amateur bands, because as fate would have it, literally on the day I went for my exam... I managed to shut the attached antenna, a rigid and beefy Sharman RH770, in a car door, and because it has no "give", it ripped the antenna socket clean off. After soldering it back on, the squelch would no longer open; repairing a broken trace around the AGC fixed that but now probing the RDA1846 RF generator chip showed no audio output. So transmit works, but not receive. Ooops.

All is not lost, though. I have another B5 on the way. I did still get to use it on Business Light a few times, so here goes:
RF Output: After all, this is of course why you would buy one of these in the first place. It's rated for 5W output with harmonic suppression of -60dBc. I measured 5.02W and -66dBc using a very expensive Keysight/Agilent test set. Spot on. Even and balanced audio reports from the other end of my contact; they literally couldn't tell it apart from the "standard budget HT" Yaesu FT60 which is six times the price!

Receiver: Clear, LOUD audio. Never had a problem with hearing folk, at least until its unfortunate car door accident. There is a pager transmitter local to me which makes the "newer" handheld spaz out, but the B5 had no issues dealing with 800W of VHF radiation a handful of metres away. It's specified for an intermod rejection/ACS figure of 60dB but that's a conservative measurement, I think. Sensitivity is the standard 0.2 μV @ 12dB S/NAD (i.e. the voltage at which signals start to be distinguishable from noise) but anecdotal reports from others suggest this varies a bit.

Features: ...it's a budget radio. It receives. It transmits. It's the ham radio equivalent of a Nokia 100 and I'm cool with that. I'm not going to masturbate over LCD colours or tone scanning or lack of System Fusion or APRS or DSTAR or any of that. "It Just Werks".

Quirks: The five digit display is enough to store names of repeaters (GB3XX) but God help me if I want to store my local ILRP gateway (GM1PLY). The superfluous third button on the left hand side is annoying, but can be hooked up as a backlight toggle if you're very careful. I intend to practice this backlight mod on the old handset and then if it's successful mod the new one too. Finally, I've triggered the big orange alarm button more than once. Completely unnecessary for amateur use, I removed the button cap to avoid pushing it by accident.

Overall: If you're new to radio, as balance between performance and price goes, this is literally the gold standard against which all other budget HTs are judged. At least for now...

Baofeng UV-5RA


After having used it for some time, I'm now convinced £25 may even be too much for one of these. It looks like a toy, it feels like one, and sounds like one on the air. If you have nothing else to compare it to, I guess it's okay, but I've been relatively spoiled by the B5, I think.

RF Output: Rated for the same as the B6. 3.8W out, -50dB. Power much less than advertised and legal by a gnat's pube to use on the amateur bands in the UK! The UV5R's are all instantly recognisable on the air due to their tinny, shallow audio. You literally have to shout into the mic to be heard, and this doesn't go away with a speaker mic, either.

Receiver: The less said about it the better. The UV-5RA frontend does not like strong out of band signals one little bit. With the squelch set to maximum, I still get SCRREEEEEEEE SCREEEEEEEEE Every. Five. Seconds as a new pager transmission comes through a mere 10MHz away from where the radio is sitting. I'm getting a little tired of "all stations on net difficult due to local QRM", hence the replacement B5. And hey, I'll have spares now, woo! So to sum up: unusable near powerful VHF transmitters, but okay in the middle of nowhere.

Features: More features than the B5, but I think not enough to justify buying one. It can decode DCS and CTCSS from a transmission (useful only to pirates, really, in order to break into Business Band comms), three colour LCD and a decent screen. If these features are important to you, cool. But they're not for me.

Quirks: How many years do you have? :)

Overall: I don't see what all the fuss is about, or for that matter, how people can so readily recommend the UV-5R system. It's junk. As soon as the new B5 arrives, it's going to be put to work possibly doing APRS or something, but certainly not for voice. I wouldn't even sell it as I wouldn't want someone's first taste of amateur radio to be this. "Caveat emptor: this radio is s**te!"

Baofeng BF-888s

Take the B5, remove the screen and the keypad, make it UHF only, halve the power output from the final amplifier and give it an annoying voice that proclaims PLEASE CHANGE BUTTER when the battery is running low, and you have the BF-888s. Similar on-air performance, which for £15, isn't too shabby at all.

I wouldn't recommend it as a first radio, but if you need a handset that's 70cm/UHF Business Light only, and doesn't completely suck, you can't really go wrong with it. It feels cheap and shabby but has taken a fair bit of abuse with no issues.

Omake: Realtek RTL2832U "SDR"


As a software defined radio, alongside the Flex, or the BladeRF, or the SDRIQ, or hell even the Softrock RXTX, it has next to no dynamic range, hardware bugs out the wazoo, it's electrically noisy and it's USB2 (and therefore limited in bandwidth): by the numbers, it should be good only for the bin.

It's a f*cking amazing piece of kit that I don't know what I'd do without. As well as DVB-T, DAB and FM reception:
  • couple it with an up converter and it's a general coverage HF receiver
  • couple it with a downconverter and it can be a satellite or radar receiver
  • out of the box it makes a halfway decent spectrum analyser
  • use dump1090 to turn it into an ADS-B receiver
  • add a noise source and a directional coupler, and it's a vector network analyser
  • add a transmitter and you can use it as an APRS digipeater
  • it can be used to listen to Airband, DMR, trunked/fleet radio, marine traffic, amateur bands, public safety, GSM, you name it, if it goes over the air, this thing can probably pick it up.
The best bit? They cost about £7. For this insane balance of price and flexibility, this is by far and away my favourite bit of RF kit.

And, it's also what got me to take a second look at this hobby, and pick up where I left off many years ago...

Monday, 16 February 2015

The Last Leg: Zero to M0 Part Two: Electric Boogaloo

What an apt title. Ha.

No waffling intro today: straight into the heart of the delicious meaty pork pie that is voltages. Yes, I'm aware that sentence is gramatically incorrect; no, I don't give a flying f....

Warning: this post contains maths, which may be unsuitable for small children and arts students. It also contains violence and scenes of a sexual nature from the start and throughout*.

*this may be a lie.

SI Prefixes, Revisited

When working with quantities such as voltages that can vary significantly in value, it's a royal pain in the backside to write out whole numbers. The big fat cables that carry electricity to my place don't say Danger of Death: 275,000 volts because that just sounds and looks a bit ridiculous.

So instead, the sign says Danger of Death: 275kV which fits on that tiny sign a lot better, and even the dimmest of lay-folk know that anything with kV on it probably shouldn't be touched.

Kilo then, obviously, stands for a thousand, alongside being the phonetic letter K.

If you've worked with computers, you've also already met Mega, Giga and Tera, generally suffixed with "bytes", and ham radio and computing fit together like butter and crumpets so I'm not going to duplicate effort here.

You should, however, be able to convert these to powers of ten:

x kilo = x thousands = x, followed by three zeros: x×103
x mega = x million = x, followed by six zeros: x×10
x giga = x billion = x, followed by nine zeros: x×10

Ergo, 275kV is 275×103V. Simple, eh?

This is what is known as engineering notation, and I use it a lot from here on out, so you should probably nail it here before continuing.

What happens if you stick a minus in front of those powers? You get Real Man Fractions:

x milli = x thousandths = 0. followed by up to three zeros and then x: x×10-3
x micro = x millionths = 0. followed by up to six zeros and then x: x×10-6  
x nano = x billionths = 0. followed by up to nine zeros and then x: x×10-9
x pico = x trillionths = 0. followed by up to twelve zeros and then x: x×10-12   

So when you see a capacitor that says it's value is 68pF, its value in farads is 0.000000000068F. I say "up to" because you'll notice there are only 10 zeros there: 68 takes up two of those digits, so you work back towards the initial 0. Small numbers are weird like that. 68pF is a really small capacitance: conversely, 1F is a very, very large capacitance and you don't want to be on the receiving end should you bridge that big bad motherf****r with your fingers by accident (what fingers?)

TOUCH ME, YOU BIG GIRL. GO ONNN. MWAAHAHA.
Electromotive Force (EMF) and Potential Difference: Not One And the Same After All.

I spent well in excess of a decade believing these were the same thing.

Spoiler alert: they aren't.

Oh, and I felt I needed to clarify EMF here: since a bunch of sad lonely people think "EMFs cause cancer" cannot into science, they will inevitably come here, look for articles regarding how radio waves cause cancer, AIDS and Ebola, and leave disappointed. If this is you, go away, now, and don't come back, ever.

When you think about it, electromotive force and potential difference... it's there in the name, isn't it? While they're both measured in volts, electromotive force is the "push" that a battery or other power source gives to electrons going round a circuit, while potential difference is the difference in electrical potential energy between two points on a circuit.

All batteries have an intrinsic resistance, known as the ESR or equivalent series resistance. This is also known as the source or input impedance (impedance simply being a fancy name for resistance; hence the reason it's measured in ohms). When you are measuring a battery in-circuit, you're not measuring the EMF but the potential difference with the battery's ESR applied. Measure the battery out-of-circuit, though, and since there is no current flowing through it, the ESR does not apply and only then are you measuring the EMF of the voltage source.

If you short a battery - never a good idea - the battery's entire EMF is dumped across this internal resistance, which often is only a few ohms, plus the (pretty insignificant) resistance of the wire. For example, if we have a 9V battery that has an ESR of 2 ohms, we can use Ohm's Law to determine the current flowing across that short:

I = V/R
I = 9/2
I = 4.5A

9V batteries are by and large only rated to deliver a few hundred milliamps. 4.5A is a fair bit of current, and across 2 ohms will be dissipated as a lot of heat.

If the battery (of a known EMF, as measured out-of-circuit) is in a circuit, and we know how much current is flowing, we can also determine the ESR of the battery itself using the formula

Resr = (Vemf - I×Rload) / I

So, say we have a load resistance of 10 ohms, a measured current of 200mA and our voltage source is 5V:

Resr = (5 - 0.2×10) / 0.2
Resr = 3 / 0.2
Resr = 15 Ohms

This ESR is also why, as you increase the load on a power source, the voltage coming out of the power source will drop. How much voltage droop you get depends on the ESR of the source, which in turn depends to some extent on how well regulated the supply is.

But anyway: that about wraps it up for this session, next time on a series of posts that will probably get a less cliched name, eventually, we'll be looking at more depth at passive components such as capacitors, inductors and resistors, and what makes them work.

Here's the mandatory donation button, in case you feel compelled to do so. Rather than buying me a pint, as one person has already proposed, help me get my grubby mitts on a new radio! :)


Sunday, 15 February 2015

The Last Leg: Zero to M0, Part One

I apologise (again) for not posting in a while.

Blame this. That's right: I now hold an Intermediate licence: took my test on the 29th of January at Stirling DARC and got a perfectly respectable 40/45. I was aiming for full marks, but damn, some of those questions were a pain in the backside due to the way they were worded, and having more than one technically correct answer!

So what now?

Well, for one, I'm working toward being able to get my first HF rig: I'm torn between the Yaesu FT857D, or the Icom IC706MkIIG. Within my budget is also the Flex 1500 SDR but I'll be wanting to stick a PA in front of it and there's no VHF/UHF. It'll represent my first significant investment in amateur radio since getting my licence. You can see the status of the "HF Radio Fund" at the top of the page.

Secondly, I'm working toward the Advanced licence now, the big cheese, the top dollar, and the dog's proverbials as far as amateur radio goes.

During the course of my studies, I'm going to be making detailed notes right here on my blog: feel free to use them in your own. I'll be writing the notes as if I'm teaching a third party; that's just how I roll.

The RSGB, among others, suggest a decent (and silent, non-programmable) calculator can be brought into the exam and is essential for Advanced studies due to the slightly more advanced maths involved, and consensus seems to be the good old Casio FX-83GT+ is the best tool for the job. I picked mine up in my local Morrisons for £4 - bargain! It can be had on a certain well-known site whose name is an anagram of 'Yabe' for about three times that.

The first thing you should do is download a copy of the Advanced Licence Syllabus. It's bedtime reading; i.e., if you try and read it all in one go, you're going to end up falling asleep.

The Betts/Hartley book is recommended by many folks to help you study; but really, you don't need it all that much, just make sure you've gone through the syllabus and can tick off each and every point, and you'll be fine. This is intended to (roughly) be the scope of my notes here.

To sum up the advantages of upgrading your licence:

FoundationIntermediateAdvanced
Power10W (10dBW) erp pep max50W erp pep max (17dBW)400W (26dBW) erp pep max
Restricted (no-op) bands5MHz, 2.4-10GHz5MHzNone
Maritime operationNoNoYes
Can apply for a Notice of Variation (NoV)NoUnattended Operation & Beacons onlyAll
Can adjudicate examsNoYes, Foundation onlyYes
Can hold exams (as an Examination Secretary)NoNoYes
Can hold a Club callsignNoNoYes
CEPT T/R 61-01NoNoYes

You will, obviously, need to have gained the prior Foundation and Intermediate licences prior to taking the Advanced. This is a huge step up from the Intermediate!

The passmark is 67%, or if you are using the QADV software, you should be aiming for a mark of 85% or more, realistically.

PART ONE Licence Conditions

Something new to you at this licence level, is the fact that folks without a licence can operate your station under supervision.

Huh?

Well, since as an Advanced licensee, you can hold exams, this means that at some point, you'll need to guide a potential Foundation ham through their practical! As long as they are on a registered training course, i.e. one that the RSGB knows is happening and will lead to a licence, then they may operate the equipment for as long as it takes for you to tick off all the items on their Practical Assessment sheet.

In addition, for the purposes of demonstrating amateur radio to others, you can let non-licensed persons use your station to send short "greetings messages" to other hams, so long as you are in control of the transceiver. What this actually entails is the subject of some debate, but to my understanding, they may operate the PTT but not the VFO, DSP, gain, or anything else.

What constitutes a greetings message? Well, the current licence terms are kind of vague about this:

3(4) Only where this Licence is a Full Licence may the Licensee permit a non-licensed person to send a Message using the Radio Equipment provided that the Radio Equipment is operated by the Licensee.

If we hop in an Internet time machine and look back at the old, now deprecated BR68 document, it gives us a better idea:

1(8) Having regard to sub-clauses 2(10) and 3(3), greetings messages may be sent by non-licensed persons provided that:

(a) it is under the direct supervision of the Licensee or other Authorised Club Member (in case of a Licence held on behalf of a club), who must operate the transmitter and identify the station; and
(b) each greetings message does not exceed five minutes; and
(c) greetings messages may be sent and received only within the United Kingdom or to and from stations in the United States of America, the Republic of Maldives, Gibraltar, Malta and Falkland Islands. Greetings messages may also be sent to or from stations in Canada and Pitcairn Islands provided that each greetings message does not exceed two minutes and that each person may only send one such message to each station with which the station is in contact.

For those of you that need reminding, that's calls starting with A, K, N, W (USA), 8Q (Maldives), ZP9 (Gibraltar), 9H (Malta) and VP8 (Falkland Is); as well as VE (Canada) and VP6 (Pitcairn Is).

I guess the procedure would be something like:

PA6ABC, this is MM0XYZ supervising John Smith from Somewhereville Scout Group for a greetings message, handing the mic over now. - greetings message - PA6ABC, this is MM0XYZ, back on the mic.

Now this could all be well out of date and I'm talking fluff, but I'm sure the actual content of a greetings message is not something that's tested.

You might also have noticed by now that the UK has not two prefixes - G and M - but also, technically at least, V and Z! V and Z countries - like VE, VK, ZL, ZP9 - are all Commonwealth countries. A bit of callsign trivia for you - this is something else probably not tested.

You also need to know the meaning of Disqualified Person: a very good recent example is this bellend... basically, they can't even touch your radio, so don't let 'em. They've been banned from operating on the amateur bands for good reason.

Maritime & international operation

With the Advanced licence also comes CEPT operation. That is, instead of having to turn up in an international destination and apply for an amateur licence there, you can simply plonk down and use the destination's prefix. So if I were to go to Dublin, rather than having to apply for a new Irish callsign I could just operate straight off the bat as EI/M0XYZ (if that was my call).

This is known as reciprocal licensing, so called because Paddy from Wexford could come over to Scotland and operate as MM/EI3PDY (assuming that was *his* call).

CEPT refers to the The European Conference of Postal and Telecommunications Administrations. Yes, this is often an exam question! Why CEPT rather than ECPTA? Well in French, just like with 'UTC', that mouthful is Conférence Européenne des administrations des Postes et des Télécommunications... They published a "recommendation document" called T/R 61-01, which defines what countries you may operate in and what privileges you get. The full text is here.

So with this comes the ability to operate in international waters and past the low water line in general! If you are operating at sea, radio conditions are a little different than you are used to on land.
  • You MUST seek permission of the Ship's Master before operating. If, for example, you are on a cross-Channel ferry, this might not always be possible, in which case, DON'T OPERATE.
  • If, for distress reasons, the Ship requires you to maintain radio silence, DON'T TRANSMIT. It's a serious crime under international law to fail to maintain radio silence and the sentence can be pretty harsh. Listen by all means to assist in the rescue effort if you feel you have to, but don't push that PTT!
  • You should use the suffix /MM (maritime mobile).
  • You should also use the band plan pertaining to the IARU region you're in; if you're just doing short hops on a boat, though, this shouldn't really affect you.
NoVs

One more quick thing I wish to touch on is NoVs. These are variations to your licence which allow you special privileges that you would otherwise have to ask for. As of Feb 2015, these are:
  • 2kW Special Research Permit Allows you to run up to 2kW for research purposes. You have to provide Ofcom a good reason as to why you need that much power and the steps you are taking to minimise RFI. 
  • 60 Metres Allows you to use the 5MHz band as a secondary user to the MoD.
  • 2 Metres - Extension Gives you an extra 1MHz at the top of 2 metres (146-147). Not valid in Scotland feckin' cheeky wee bastits...
  • Microwave EME Opens up ~2.3GHz for EME use, up to 400W.
  • 275GHz Not yet available, but this is basically the "top, top" band. You'll probably need a lead vest, balls of steel, an SDR and one hell of an upconverter to work this one.
  • Beacons/Unattended You already encountered this one at Intermediate: the one that gives your APRS iGate that funky MB7 callsign.
  • Golf Bravo Two Romeo Sierra (GB2RS) Allows you to read the RSGB news bulletin on VHF using the callsign GB2RS. If you want folk to recognise your callsign in an instant, this is how you do it... it's a thankless, unpaid job, though, and more often than not you'll be talking to dead air.
  • Repeater Keeper Does exactly what it says on the tin, but now you can carry analog voice. More info here: old, but still relevant.
The remainder of the syllabus you already encountered at Foundation & Intermediate level, so there's no need to go over it again.

That just about covers the whole of Licensing for the syllabus: next part will be the Technical Aspects, starting with EMF, Voltage, and expanding on Ohm's Law, before getting on with the real mathematical nitty gritty.

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