Category: The Family

Radio Waves (by )

I really love learning things, and recently I've finally been removing a long-standing thorn in my side - the fact that I don't really understand radio frequency electronics and the propagation of radio waves.

I've tried to fix this a few times in the past, but the resources I'd read never seemed to quite explain the whole picture - and I couldn't see how to piece the things they explained together into one coherent understanding of the electromagnetic world; they were clearly only shedding light on little corners of a totality that still remained mysterious to me.

Well, there are still gaps in my understanding... but I've made some progress, and in the hope that I can help others struggling with the same confusions as I was, I'd like to share my way of understanding it all.

One thing that bothered me was that explanations of transmission-line behaviour seemed to flip between talking about instantaneous voltages and currents at some point in the line, sampling the analogue signal travelling down the line - or talking about an RMS average voltage or current, and thereby causing me to struggle to make sense of what they were saying. But I think I now get transmission lines to some extent (although I'm still hazy on waveguides, because I've not gotten around to looking into them yet). And I was never quite sure what the impedance of a whole transmission line really meant, regardless of its length. If I had a transmission line and put a resistor over the end of it, and hooked it up to a battery and an ammeter, I knew that the current flowing would depend on the total resistance of the line and the resistor at the end - which would depend on the length of the line, as its resistance would be in ohms per meter. So what the heck was this impedance thing about? How did impedance mismatches cause reflections?

So, here's how I think about transmission lines now. The "DC model" of hooking a battery up to one end of a line and reading the current that flows into it is, of course, perfectly true - we can set the circuit up and test it; the reason it doesn't contradict with this weird parallel world of impedances is that the DC model is a steady state model of the system. When you first connect that battery to the line, current is going to start flowing into it, crawling along at a sizeable fraction of the speed of light; but until that current has reached the end, flowed through the terminating resistor, and flowed all the way back, it can't possibly have communicated any information about the total resistance of the line and its terminating resistor... So how much current initially flows from the battery, and why? Of course, the line can be thought of as two series of tiny inductors (with resistors in series, if we assume the inductors are perfect) with tiny capacitors connecting the two conductors, due to the inherent inductance of the wire and the inherent capacitance of the gap between them; you can imagine that the current from the battery has to charge the capacitors through the inductors for the voltage/current surge to propagate down the line. But what made "impedance" really click for me was going back to the basics of Ohm's Law and seeing it as a ratio of voltage to current. At any point along that transmission line, a certain instantaneous current will be flowing - and there will be a certain instantaneous voltage between the two conductors at that point; and the voltage divided by the current is the impedance.

So, if a 12 volt voltage source is connected suddenly to a 50 ohm impedance cable, an instantaneous current of 0.24 amps (12̣̣̣̣÷50) will flow. Now, as Kirchoff's current law tells us, the currents flowing into a node must sum to zero; so with the imaginary node at any point on the transmission line connecting two halves of it, the input current must equal the output current (although some current may be lost to resistive heating or leakage, that's not relevant in this case). So what happens when there's a change in impedance at some point in the transmission line? The current must remain the same, but the impedance changes - so the voltage must change, to make Ohm's Law still hold. If my 50 ohm cable is connected to a 75 ohm cable, that 0.24 amps flows into it and changes into a voltage of 18 volts (0.24×75). Which is why high impedance transmission lines are less lossy; a transmitter putting a watt of power down such a line (with proper impedance matching) will push out a higher voltage with less current that one putting a watt of power into a low impedance line - and resistive losses in the cable are worse for higher currents.

How about the reflections when impedance changes? I'm still a little hazy on this, but I think it's something along the lines of this: imagine a point just where the impedance changes in our example of moving from a 50 ohm cable to a 75 ohm one. A current is flowing into that point, but the voltage is higher after that point than before - which is going to create a current travelling back the other way. Where I'm hazy on is how this happens at junctions where the impedance falls (is it to do with the fact that the current flows alternately backwards and forwards, so the junction is traversed by current in both directions anyway, and the phases where the current travels from low to high impedance are what create the reflections? If so, isn't that a kind of rectifying action, that will create harmonics and intermodulation? But what is the "direction" of a signal travelling along a line, anyway? If we froze the signal in time, we'd just see a sine wave of voltage and a sine wave of current along the transmission line - if we restart time, how does it "know" what direction to propagate in? Something to do with the relative phase of the voltage and current waves?) So, yeah, I've a little more to learn there.

But this model of impedance does explain a lot. I wondered why the angles of the radials of a ground-plane monopole antenna affected impedance, but now it makes sense - the end of the transmission line basically spreads out to become a dipole, or a monopole and its ground plane; the electrical field of the travelling signal has to cross a larger region of space, so it makes sense that the voltage required to do so might vary depending on the amount of space crossed. All the mysterious constants, like the fact that a dipole trimmed to 0.48 times the wavelength has an impedance of 70 ohms are really down to the electromagnetic stretchiness of space: the impedance is the voltage required to push one amp along a transmission line (a dipole antenna just being an oddly-shaped transmission line, handing the signal over to the even weirder transmission line that is free space itself), and that is a function of the permittivity and permeability of that space.

Antennas with multiple elements are confusing, but I'm not sure anybody really understands them - as far as I can tell, the design process is almost always to mock it up in a finite-element computer simulation or build a prototype and tweak the design until the desired parameters are obtained experimentally; the mutual interactions between the elements (not to mention ground, support structures, and the transmission line feeding the antenna) are just too complicated to analyse.

I really don't get why there's a near field and a far field (or that funny one inbetween that, I think, is just a mixture of the two). Does the antenna both far and near fields at once, and the near field is stronger but doesn't spread out far, so the far field is negligible when close to the antenna? Or does the antenna create a near fields, which "decays into" the far field as it spreads out? Nothing I've found seems to explain.

But, I can understand how to run a cable to a dipole or monopole antenna, manage the impedance transitions, and make it radiate efficiently. That's progress!

October Events and Stuff! (by )

Lace Skull candle

September was frantic and wonderful - the Gloucester History Festival was amazing and has started me down the paths of several new and exciting things for the future! And I have a lot of events photos and sketchtember pictures to share with you all.

But for now it is October the 1st 2018 and this new month hold even more in it that September did! Namely The Cheltenham Literature Festival, Gloucester Poetry Festival and Frightmare Halloween Festival! I am involved in parts of all three of these over lapping festivals - wish me luck!

And then as my fun/de-stress there is Inktober - a drawing challenge that was one of the major factors in me actually producing the art work for Love: A Stranger Dream.

And then there is GothNoWriMo which is a writing challenge and shall see me writing yet more of the Punk Universe (which I will be releasing parts of properly next year!).

So here are the current confirmed dates!

Sat 6th Oct 7 pm Frightmare Preview Night at Overfarm Gloucester - ticketed event (prices vary)

Tues 9th Oct 7pm Operation Beehive in Swindon part of the Gloucester Poetry Festival and a Gloucester take over of the regular Ooh Beehive Night

Thurs 11th Oct 7:30 pm - Hammer and Tongues All Star Poetry Slam in Cheltenham, part of the Cheltenham Literary Festival at The Bottle of Sauce tickets are free and can be booked here

Fri 12th - Sat 13th Oct Young Gods showcase at Elmbridge Primary School 6:30 pm Jean and Mary's Drama group

Young Gods Showcase

Fri 12th - Sat 13th Oct Frightmare Scare Attraction Over Farm Gloucester from 7 pm

Sun 14th Oct 2-4 pm Poetry hosted by Sarah at the Gloucester Waterstones part of the Gloucester Poetry Festival - free event including goody bags as part of Books Are My Bag

Poetry in Waterstones Gloucester

Tues 16th Oct 2-4 Book Wyrms at Gloucester Library a poetry event with guest poets hosted by Sarah - part of the Gloucester Poetry Society and free event

Book Worms Gloucester Library

Fri 19th - Sat 21st Oct Frightmare

Sun 21st 2-4 pm Poetry at Gloucester Waterstones as part of the Gloucester Poetry Society hosted by Sarah

Wed 24th Oct 2-4pm Book Wyrms free poetry event at Gloucester Library part of the Gloucester Poetry Festival hosted by Sarah

Wed 24th - Sat 31st Oct Frightmare Halloween Festival at OverFarm Gloucester

A Canal Walk and Whole Ears (by )

Yesterday me and Jean went to get her ears pierced at a friends house - I don't have pierced ears - family members range from multiple piercings dripping silver and charms to no body ornamentation what so ever. Jean has been nagging me since she was 7 but I wanted her to be been grown up enough that I felt she could make an informed decision on the subject. She saved her money and it was time.

So we dropped Mary off at another friends for an adventure day and walked with my shonky old phone deciding to be flakey were the navigation tools were concerned. We got there only half an hour late and mainly that was due to me stopping to take photos. We were passing a building site - and couldn't resist the rubble - sadly there were some shots I just couldn't get due to some pesky fencing.

We walked via the docks around to the canal by the building works and then back via the canal.

The Bones of the City

the cities bones jut

The bones of the city just through to a skyline grizzling with an autumn struggling to be born.

A remnant ghost of structure

Remnants of structures long abandoned and decaying in misuse give up their ghosts to the wind and rain.

Opened

Buildings from an age lost a century or more ago are slit open for us to fest upon the hidden spaces that crept from them in the twisted shadows of the city crawling towards progress.

chimney Gloucester

Lost last ones of this time, hover on the horizon watching as a new land and time arises around them.

what's beneath next to

Preparations are made to hide new sentinels within to keep us healthy to keep us safe from drowning within our own wastes and needs.

Work site

Cages and guards await next to the monsters that will make their new homes... beneath and beyond the sight so that they are not ugly, as if utility is something to be ashamed of.

Insectile machinery

Like megalithic bugs all legs and spindles of sensors they wait, dormant and filled with the potential to create or destroy, the construction of... something.

green tanks waiting

Waiting in the colours of the sea, waiting alien and surreal on a rubble field that no war has produced but the minds of those striving for a place to be, to grow.

tanks waiting to go into the ground

The inflows and outflows of change and all the could bes and should bes and moments when all hangs in the balance.

tap or valve opening

Waiting for that perfect fit.

Not a tank

Dormant sleep - this land is cocooned waiting.

Tower of an older age

Memories of what it had been when it had thrived with boats and industry and polluted skies and people becoming and learning and striving. Things were learned and some of the learning is forgotten but much is not and so the land remoulds itself at the hands of these apes that tell stories of their own existence.

Over seeing the rubble

Beyond the tower and scars of industry lays a hill side that is older than the city and the roads and the chained and kept waters of the canal and it reminds of natures way and of how time will claim all things... grinding us all back to... star dust.

The Ear Piercing

Jean's comments on me taking the photos and discussing with her the poem I was going to weave and create out of them: "it's the first thing about me people find out - I have a weird mother, sometimes it's a good thing and its good weird, sometimes its funny and everyone laughs and sometimes its narghahahahahah - so embarassing there aren't even any words for it."

Also she had some frustration that I was making us late but the truth is that I just can't walk very fast and taking photos helps me walk further as I rest a little whilst I am stationary.

We had tea and chat and stroking of cats and hugging of babies and looking at Warhammer and lego awesomeness and then it was ear piercing time. I held her hands but she didn't even wince!

short hair and ears pierced

pierced ears

We then walked into town taking vids for our summer vlog though Jean reckons no one is interested in me rabbiting on about various insects - other than people like me and there aren't many of them apparently!

We ate food and felt sorry for our serving staff who were having one hell of a day with dealing with complete SHITS of customers - starting with a vicious old lady and ending with the family who were insisting on free refills in new glasses aggressively after only taking a few sips from it >:(

Then it was on to the accessory shops to pick up the fluid for cleaning the piercings to reduce the chances of infection and a look in various gaming shops etc... I may have bought rainbow ear rings for both of us (mine are clip ons hers are spiked) and some Lord of the Rings colouring books that were reduced to two quid.

Then it was bubble shake and tea stop before the final push through to walk home - sadly I have to have regular long sit downs like this if I am going to do the walking but was desperate for an explore and outing. Jean drew an unflattering picture of me with facial hair and looking old, I drew her - she said its not fair because I made her look nice and we were supposed to be doing charactures. I think she looks scary grown up now and that she has stolen part of my teen age wardrobe in the form of my plaid shirts.

I will put the second part of the canal walk into a different post as it will be another Poetry Walk entry and likely be a little long!

So just to end with - I think it was a good outing - Jean says it was a father/mother-son/daughter outing.

p.s. the land around the canals that appeared to be wilderness like when we first moved here were actually brown sites - ie they had been built on in the past and were laying derelict - they had once been a thriving part of Englands transport network with goods yards and workers housing. So though I like the wilderness I will always be happy with brown sites being built on rather than green belt or agricultural land. The waterways have been being heavily restored and are a wonderful walk now in a way that really was just not possible before - and they are providing lots of bits for wildlife - I was however sad to see the amount of bottles and things thrown into the canal but that is part of an on going litter and refuse collection issue the city has rather than anything else - I think my one remaining concern is that the housing is all being built on areas which really are very likely to flood.

Angry with the Universe (by )

My life in general is awesome - I have plenty of work, my kids (bar trying to get Mary to brush her teeth or do her homework) are fab, and we have a lovely kitchen and bathroom about to be finished off. We are not struggling for food or cloths or shelter and I have lots of books and music and films and games....

But there are several things that are killing the joy and which have apparently closed off any emotion in me other than rage.

One is mental health attitudes and and cuts to the nhs which I now believe is costing lives and not just random lives that I can only extrapolate about. But people we know and those shining stars so full of grace and wonder and pain are now gone. They leave the world a dirtier mucker place, and they are multiple and they're suffering was extreme and yes there is anger there as well.

Another is general politics and how I see it already impinging on the world around me in direct and tangible ways - the increase in the homeless and the need for food banks, the street litter and piles of stinking rubbish that build up as the infrastructure is failing due to under funding. Again lives will be lost with both these things and that angers me, they are needlessly thrown away.

Tolerance and understanding are being kicked in the teeth and all that human and equal rights stuff. Once I thought I was being talked down too because I was young, then I thought it was because I was fat and using a walking stick or wheelchair, now I realise it's because I am a woman because it hasn't bloody well gone away regardless of size or fitness or age.

But mostly at the moment my heart is broken and doesn't seem to be at all interested in even trying to heal - because I have just spent weeks in a lot of pain and bleeding and loosing smelly gunk, not knowing if the baby was dead, dying or now rotten within or what order it would decide to do those things in. I was petrified that it would go the same way as before and that I would find myself fighting for my life in A&E.

Friday we got the definitive answer and there was no longer a viable pregnancy - in fact there was no longer a pregnancy at all. At least I didn't have to deliver a placenta the size of a small baby this time and haven't ended up incapacitated. But it does leave me with a worse mental shift - last time I was so ill and it was so sudden and we had been so excited and hopeful that it seemed natural to be devastated and upset and weak and wobbly - I don't know how to react to this one.

It was a lot earlier and I knew I was in the danger zone still and I couldn't bare to hope, and when they did the emergency scan I knew that it was over then - but I still had weeks of trying not to hope of trying not to think of weather it was alive or dead or rotting.

Weeks of it being treated as a viable pregnancy with no options given to call it quits - I will go through high water and hell for a maybe baby but I need to be given the choice because then I am a warrior and not a slave.

I had to call in some friends to help look after me as Alaric was away with Jean that first weekend, they were the only people outside my parents and brother who knew - I couldn't bare to say what was wrong. And some who helped out didn't even know as I just labelled it as medical problems.

My friends all went above and beyond in their help and support - once again I was struck by how truly lucky I am.

I've been assured that I'm not too old and that there is still a good chance to have a baby - due to the ectopic I had before I can now self refer to the hospital without having to faff via the GP about pregnancy but I need blood tests just to check things like my B12/folate levels and blood clotting - both things that have been issues for me in the past. But the policy is that you have to have had 3 miscarriages in a row but I don't want to do it like that if I am loosing them because I just need some B12 injections I just want the blooming B12 injections.

I fear it is my stupid blood group and I'm not sure what they can do about that - I was allergic to Jean but Mary is the same blood group as me.

The baby had implanted very low down. I didn't bleed out like before and I am hoping to avoid another op - the scan suggest that I should be fine.

In fact the scans show that my left ovary and tube etc... look fine - this was news to me as they were mullard but appear to have repaired themselves. That is good news.

I am clinging to such things and my work and my kids - I am a She Wolf defending her cubs at the moment - regardless of the fact that one of them is bigger than me - I am also sure I am hen pecking and trying to look after them too much. I am being snappish and curt with people and yes I am angry - very very angry and it is pretty much the only emotion I can feel at the moment.

Sorrows appear to piling up on my friends and family and so I haven't made this as public as I was going to to highlight issues around miscarriage because I didn't want to pour more sorrow onto them.

I haven't yet cried over this - that is not a good thing - I now it's not a good things but I can't feel it. Bizarrely when I am out and about I appear cheerful and happy - but I am not - I feel like there is a dark whole inside sucking everything in.

I barraged the medical professionals with questions on what could I do differently and there is nothing. I'm looking to see if I can pay to have the bloods done and that makes me angry too because if this had been us when we were having Jean that would not have been an option and it means poorer people are already risking life and womb.

A Bad Mummy Moment – or the Cusp of the Teen Years (by )

Bad Mummy moment - I swore at my eldest because they were refusing to get their bike ready for a Scout cycling event as I was trying to tell the youngest that they couldn't ride their bike to the allotment - youngest took the opportunity of distraction to ride out of the garden on her bike whilst I was trying to get eldest to function and sort her bike out.

Youngest was going to that allotment on that bike regardless of what mummy said, eldest was not going to the biking thing on her embarrassing bike regardless of what mummy said. Both felt aggrieved at allotmenting because they are convinced its my hobby that I am making them help with. I'm like no growing food and knowing how to ride a bike are essential survival skills - after all when the zombs apoc hots you'll need them or iff the aliens win out electricity how else are you going to run away 😉

Youngest obviously heard the swear word because later when I was telling my mum on the phone she asked who I was telling I said "nanny" and she repeated the word - under her breath in a very grown up way :/

My Dad say's this will be a funny story along with child trying to use a shoe horn to get me off the sofa whilst I am on the phone apologiesing for for forgetting his birthday that my mum had phoned me up to remind me not to forget - littlest was doing this because she wants a cat in her bedroom and she's not allowed to pick them up and carry them because she doesn't it properly and it's not fair on the cats.

Not happy that I swore - I am finding things very difficult medically and emotionally at the moment - more on that tomorrow after the hospital appointment,

Feeling a tad frazzled = world is being hard work at the moment pretty sure I am failing at everything - so eggy French bread with caramel latte ice cream - GF whole mill bread dipped in whisked egg and dry friend and then dipped in brown sugar and cinnamon.

Eggy Bread French Style with caramel latte ice cream

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