Thursday 18 October 2018

FT-857D Squelch Fault

Some weeks ago, I noted a distinct lack of apparent activity on 2m FM. Now, this wasnt too unusual, as the band is sparsely populated around here anyway save for CB type tools with no respect for any form of operating standards using it as their own private free-band.

But eventually I noticed that although I couldnt hear anything, I could see high signal strength readings! This led me to discover that the squelch had failed!

Thanks to the information from VK4SN near Brisbane, as shown here http://vk4sn.com/ft857.aspx and my trusty old Marconi 2955, ive been able to correct this fault, or at least, relieve the symptoms!

Following the instructions given, I also found like VK4SN that my new firmware values were around 170, far higher than they were before!

For the time being, I will see how it goes in this state. At some point though I suppose I will have to lift the main board (didnt fancy doing that today!) and check Q1063 as indicated. I might wait until I have located a source of this transistor first!

Tuesday 9 October 2018

BOINC-A-Phone

This evening ive made the connections to the phone's battery terminals permanent. At the same time, I made up a 2k4 resistor (which is a non-standard value, so made with a pair of 1k2 in series) to mimic the measured resistance between the 2nd contact (NFC antenna) and 3rd contact (ground) on the battery.

Supply and BSI resistor

 With a bit of cutting, it will now be possible to fit the original back cover on again!  The 2k4 resistance did indeed turn out to be the devices BSI signal, the pin being shared with the NFC antenna. With the resistor in place and the supply voltage set to 4.35V (the full charge terminal voltage of a 3.8V Li-ion cell) the device is now perfectly convinced that it has a fully charged battery attached.

All cores running WU's - 100% battery!
So my previously defunct and disused Samsung Galaxy Ace 4 is now a fully working BOINC number cruncher! There is however still the issue of heat to deal with. A quick measure with my IR thermometer shows PCB temperature of nearly 50c. Solving this is easy of course - just a fan. But it will take some thinking about to develop a mounting solution.

Monday 8 October 2018

Phenom-enal

Well I wasnt going anywhere today - not after doing the Yorkshire Three Peaks again yesterday! A bit sore to say the least! So, knowing i'd be staying in anyway awaiting deliveries, I thought i'd get the AMD Phenom CPU installed.

Before I even got the anti-static service kit out, a knock at the door put Sams new GPU in my hands. So that was something else to do while I had all the service kit out.

The AMD Phenom X4 Black Edition CPU went in easily enough, although lifting out the old Athlon chip was a bit tricky, resulting in plenty of heatsink compound getting smeared about. I probably put on a little bit too much new compound, but the cooler clamped back down ok.

So with a slightly worried feeling I re-powered the machine - the BIOS saw the new CPU immediately and invited me to enter set-up and check all was well. Windows on the other hand decided that it would be a bit awkward and just be really slow in updating the drivers and restarting, even accusing me of having a non-genuine copy for a while! But eventually it settled down and all seems to be running fine, if a little hot. Idle, the cores can site around 40c, running 100% BOINC WUs it hits 75%, and is on the very edge of thermal throttling (seen it just once while also opening some PDFs). A new Coolermaster Hyper 212LED CPU cooler is on order, so hopefully once thats fitted the temperatures will be a bit more sensible.

I also installed Sams new GPU for him, and did some cable management within his machine. At the same time I put in his spare 1TB SATA harddrive. This led to a bit of confusion as the machine seemed not to detect it! But it could be found in BIOS, and also we discovered in Windows hardware manager, just not in MyComputer? It turned out of course that as it was unformatted it couldnt be shown as it had no assigned drive letter! Soon sorted once we'd located the windows admin tools page!

I decided late that theres no real likelyhood of my ever needing to use my old phone again, so have dismantled the connector strip from the battery. Even in this state, the 2k4 resistance still exists, so this surely must be involved in the battery management in some way. Tomorrow if I get around to it, I will hard wire that resistance into the supply pins, and i'll let it settle for a few hours to see if any effect is evident.

Saturday 6 October 2018

Phenom from Kong

Rather surprised to receive a package from Hong Kong this afternoon. Inside of two layers of thick polythene shipping bag, was a bundle of bubble wrap. Inside that, a sturdy cardboard box. Inside that, another bundle of bubble wrap, containing a sandwich of a plastic chip carrier between two rectangles of high density packing foam. Inside that, with a nice square of antistatic poly foam below its multitude of pins, is an AMD Athlon X4 9952 Black Edition 2.5GHz quad-core processor!

I will resist the temptation to tear down the machine right now, and instead wait until after the weekend before installing!

BOINC crunchaphone power

Well it seems obvious that if you replace a mobile phones battery with the same voltage supply via the battery terminals, that it would power up as if there is a battery present. And, indeed, this is exactly what happens!

Here the phone is being powered from a 12V lab bench supply, via a 99p buck converter module set to 3.7V, connected using a pair of micro test clips to the battery terminals.

As you can see, all four processor cores are running their allocated BOINC WU's. (Ok I admit, it didnt work first time - I had to remember to set the project to run when on battery!)

What is harder to see is the battery level indicator, which shows 17%, and the screensaver view which has the legend "connect your charger"

Ok, so, clearly the phone cannot tell the batteries level of charge. Since the voltage is correct, and slight alterations of the supply up to and including the charging voltage, dont change this, it follows that the other two terminals of the battery - BSI and BTemp, need to be looked at. Its likely that the issue here lies with BSI, which tells the phone what capacity battery it has installed. With no signal, of course the phone cant accurately judge the remaining charge level.

I suspect that this signal is a simple resistor built into the battery, so it remains for me to see if I can establish the value required to fool the phone into thinking it has a 100% charged battery attached.

I can measure 2300ohm between ground and one of the terminals. But nothing measured to the other. Adding a 2k2 resistor between this terminal and ground on the phone didnt change the charge indication, so my suspicion now is that this value is the BTemp thermistor. That should be easy to check - i'll simply warm the battery up and measure it again!


UPDATE - Well, heating the battery made no difference to the resistance. However, I can now explain this. Ive since discovered, and proved to be the case by peeling off the label, that the pin im measuring the resistance to is actually one of the connections (the other being Vbatt) for an NFC antenna hidden under the battery label!

So im still none the wiser how to make the phone think its got a full battery.

From mobile phone to dedicated BOINC cruncher

One of the problems of making an old mobile phone into a dedicated BOINC cruncher, is power. Another is heat. And the third is connectivity.

These can be tackled in reverse order. Connectivity - well, being an old mobile it no longer has a SIM and so no mobile network. But its WIFI and Bluetooth still work. It is of course a very simple matter to just switch on the WIFI, connect to the local network, and start crunching! As the thing is no longer going to be mobile that issue can be put to bed.

OK then, we come to heat. Crunching the numbers for BOINC work units (WU's) at 100% CPU duty, is clearly going to make it hot. Again, solving this is relatively easy - just give it a fan!

Test Set-up

The test set-up shown above is being powered by USB and the fan is a 5V USB fan. Its enough to keep the phone and its battery below 40C. USB isnt really the most convenient source for this project, so later i'll be changing to a 12V source, and so to a 12V fan. But for now it does ok. You can see in the photo that all four CPU cores are in use.

A final aspect of the cooling will be to enclose the fan, phone, and any other electronics needed, so the whole project becomes a single small box of tricks.

Which leads us to the main problem - power.

The phone has a 1900mAh Li-ion battery at 3.7V. A few rough calculations based on the USB current readings, show that it would be flat in a little over 3h if used as the sole supply.  I also discovered that when crunching, the battery slowly drains even when on USB supply. Only if the battery is allowed to charge to 100% will it then remain so, I suspect due to the charge controller at this point switching the phone over to purely USB supply. But this ive found led to another issue - remove the USB, and the battery level drops alarmingly! That could be that the battery is on its way out of course. Also, even when supposedly charged to 100%, the USB current crept up close to the maximum 1A of the source. Again, probably due to the charge controllers attempt to handle a failing old battery.

So it makes sense then to plan to dispense with the battery entirely. Since I plan to move to a 12V source (as another future aspect of this project is to go green with a solar supply), then I can utilize a low cost adjustable Buck converter to give me a 3.7V 1A supply, and connect this directly to the phones battery contacts. Because I might need a back up phone, I dont want to do this permanently, so will do so using micro test clips. The only issue I envisage with this approach is that part of the BOINC clients control sets the maximum battery temperature for running the projects, and without a battery present there will be no data on this. I may need to either frig a suitable temperature setting using a resistor (a bit of a bodge), or else also add a suitable thermistor to give an actual measurement of the battery compartment temperature. This is preferable as it will be a good relative reading to the cooling system.

BOINCing On The 'Phone

Recently, a disaster befell me during a PC upgrade, resulting in a tense few days awaiting an RMA decision over £150 worth of SODIMM RAM, a wasted £15 service charge to tell me what I already knew, and the consequent expenditure of close to £600 to build my eldest lad a new PC,

Sams new machine is now almost complete (just awaiting delivery of the graphics card - running on a terrible 128MB 'industrial' card at the moment!) and its AMD Ryzen 5 processor and DDR4 RAM make it a powerful and reasonably future proof machine.

Doing this however showed me just how old this machine that im currently editing this blog from, was getting! But, it works well enough for my purposes, except that I realised I could do with just a bit more power... so, for the sake of a tenner, Ive bulked up the RAM to the max the current CPU can handle (8GB of DDR3), and noticed a quite substantial improvement. But I realised that the motherboard is capable of handling much more processor than whats currently installed, an AMD Athlon 2.7GHz dual core. I now am awaiting delivery from Hong Kong of an AMD Phenom X4 2.5GHz quad core CPU. This should pep the machine up somewhat! Plus, it will mean I could up the RAM even more, as the Phenom can handle more than the Athlon, at least up to the motherboards max.

The failed machine that we replaced with the Ryzen 5 build, was an Acer 'All-in-one', which whilst it was a pretty top end workstation when purchased, was 3 years old, out of warranty, and otherwise really had nothing going for it! When it was first purchased, I had reservations, but kept them to myself! Foremost was - "what happens when it goes wrong/needs upgrading?" well, as we discovered, what happens is you kill it!

On paper, it was clearly upgradeable. In reality, Acer clearly had no intention of letting the customer have any control! We decided to bump the RAM up to 16GB of nice fast matched pair DDR4, which we knew the machine should be able to take.We put up with the rediculous difficulty of dismantling the machine - trying to unfasten the myriad of too short cables from the very heavy screen, removing the millions of screws, heat shields etc, and having to remove the entire main board to access the RAM sockets! (no RAM access panel on the back like a self respecting laptop!). We fitted the new RAM - and the machine promptly died! After much inspection, it was discovered that the spare slot in the RAM socket was deformed (clearly faulty from manufacture) and the SODIMM stick didnt seat correctly - shorting the pins and destroying the main board chipset! All this of course made irrelevant the fact that the numerous rebuild/dismantle cycles needed to investigate the fault led to the key cables being damaged beyond repair!

So the new RAM went back. This was the most anxious part as it had been bought as a gift by Sams grandad, at a very distressing and sad time for the family. I was very relieved when ebuyers techs reported it fine and the refund issued!

So me and Sam spec'd up a new machine, ordered the parts and built it! A little more on that later...

But clearly I doth digress!...

This post is meant to be about phones and BOINC, as per the title! Well, Im coming to it!

As a result of the failed machine, I now found I had a stick of SODIMM RAM spare, so decided to see if I could make use of it in any of my other machines. Now, somehow ive acquired several laptops, all of different ages and capabilities. It made sense to rationalise them. I looked at all the specs (ignoring the Dell Latitude 400 which is my DOS machine!!!) and the RAM, and decided which of the three would be the most capable, swapped RAM about to make it the best of them. This is now my main radio laptop. The next one down, ive yet to do anything with. But the worst of them, a very old Toshiba Equium dual core, still running windows vista, I decided to play with as clearly it was otherwise scrap, and you all should know by now I dont like to chuck useful kit out.

So I have that old Tosh machine crunching numbers as a semi-dedicated BOINC platform. Its still on vista, but I might move it over to a linux build at some point if that will improve the BOINC performance. It was while setting this up, and fixing a few issues with it, I started to wonder about what I could do with my old mobile phone...

My old mobile has been sat on my shack desk for absolutely ages. Its a Samsung Galaxy Ace 4. It was very unlikely to every get used again, and worth nothing to sell. But - it has a 1.2GHz quad core CPU and an Android OS! I had run BOINC on it before, briefly running Quakecatcher and SETI@home.

Recently though my BOINC choice has been medical research. Ive cut back on the SETI work units, and ended the space and encryption projects. Apart from a bit of involvement with Climateprediction (which was the first BOINC project I ever ran) my choices now are Rosetta and Worldcommunitygrid, where I am attached to immune system and cancer research projects. It occurred to me that I should be able to set up the phone as a dedicated cruncher!

So this is what I have done, although it needs a bit of work electronically! I now have both cores of this main machine and its GPU crunching numbers, the old Vista machine crunching, my current phone crunching (on all EIGHT cores!) and my old phone!

Possible Future Blog Move

Heads Up,

Due to insurmountable difficulties with Blogger in relation to mobile devices and account tie-ins to ISPs, Im considering my options to migrate my blogs to another blog service.

Those of you who occasionally drop by to see if ive anything new going on, be aware that any links you have may stop working - at least until I tell you what to change them to!

Saturday 11 August 2018

Dew Heater Controller Lives!

ok, I know its been a while. These days, I am rather busy elsewhere so get little time to work on electronics or radio, and so the blog updates come less frequently. Some recent family issues also have given me even less time.

But, theres nothing like an upcoming astronomical event to drive the completion of a project! Last night I spent a couple of hours meteor and satellite spotting with my eldest lad. With the Perseids meteor shower due to peak this weekend, I pushed myself to finally complete the Dew Heater.

Very little needed to be done, just the connections for the temperature sensor and building a power cable. Plus testing, and finally completing the housing.

The power cable is a DC jack to crocodile clip lead, to allow the controller to be used with my many standard 7Ah SLABs. The temperature probe, which will be secured to the camera lens by the heater strap, required some cross-over wiring to connect it to the phono cable tail I already had (salvaged) in its parasitic power mode - taking it from a 3-wire to a 2-wire device.

Testing using body heat and freezer spray showed the sensors to be working correctly, and the heater controls firing as expected.

The next test will be the big one - how well it actually handles its job of keeping the camera lens demisted in the early hours of tomorrow morning! With the controller dealing with the lens and ambient temperatures, and the dewpoint, and the camera running continuous 15sec f1.8 18mm ISO 1600 exposures, all I can hope for is clear skies!

Monday 25 June 2018

Less than a week to the Ebor Way

I have been somewhat distracted from electronic and radio engineering these last months as we train for our annual charity walk. Rest assured, there are some interesting posts on the horizon, including but not limited to repairing an FM squelch fault on a Yaesu FT-857D!

For now, readers will have to be content with yet another post begging for your money!

Please if you can, support me and Bob M1BBV, as we raise money to destroy weapons and clear landmines and unexploded ordnance around the world - https://www.justgiving.com/fundraising/mag-eborway


Thursday 26 April 2018

Test - Sponsorship link widget







This post is just to test a link widget for my JustGiving page in readiness for raising money for our charity walk this year. It will be deleted once I have the link sussed.

But, if your reading this, feel free to use the link if its working and donate to our cause!

JustGiving - Sponsor me now!

Saturday 14 April 2018

ADS-B Groundplane antenna - version 2

I finally had chance to analyze the return loss and bandwidth of the wire groundplane ADS-B antenna recently, and found that it was actually tuned to 1300MHz! As this is higher in frequency than the required 1090MHz, this meant that the antenna elements were too short. Had the frequency been low, then it would have been a simple case of pruning the elements a millimeter or so at a time to frequency, but being too short means they need extending, which is all but impossible due to the enamel insulation.

So I decided that I would build a new antenna, this time deliberately too low in frequency, to allow me to prune it. I also opted to use bare 1.5mm2 copper wire, which will allow me to add length if required.

One of the most difficult aspects of the original antenna was the mounting disk for the ground plane elements. On the original this is made from PCB stock, but I wanted something that was truly circular for this one. As luck would have it, a visit to the National Coal Mining Museum at Caphouse Colliery supplied me with the perfect starting material - a brass pit check!

Caphouse Colliery pit check

 Finding the center of the disk as somewhat tricky, and even then, the hole isnt perfectly centered, but it also is a little large, so I was able to adjust the BNC socket position on the disk to be more accurately centered later.

The wire im using here is 1.5mm2 domestic Twin and Earth mains cable, stripped of its insulation. The pre-stamped small hole in the pit check, intended for hanging it on the banksmans board in the lamp room of the pit head, was perfect for allowing a small woodscrew to hold the disk in place, while ordinary masking tape held the wire elements steady ready for soldering. The elements here are cut to 85mm, allowing 5mm for soldering.

Cardinal point elements in place

With the first four elements in place, the next four were soldered in. Being a solid brass disk, and with the aid of my new 150W soldering iron, the joints were made quickly and cleanly.

Remaining elements fitted

Once cool, the assembled ground plane was removed from the wooden board, and the vertical element added. This was cut initially to 100mm, then reduced down to 90mm once soldered and straightened.
First Test

 I have yet to analyze the properties of this build, and will adjust the ground plane element angles down to achieve the correct impedance at that time. For now, a quick test of it on the ADS-B receiver showed that it is working, and seems to be working as well as the original antenna.


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Saturday 24 February 2018

Coupler?

This post only exists to allow me a way of passing a particular photo.

Coupler -




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Thursday 22 February 2018

Splat!

After returning home from work this morning, following a hard session at the gym, the ADS-B aggregation had done a little over 24h, allowing time to receive squitters from a whole weekdays worth of scheduled, charter, military and general aviation flights, plus all the overnight cargo flights.

The resulting aggregated plot, known as a 'splat', for reasons which should become apparent, for the 1090MHz Ground Plane antenna, mounted on Sams south facing windowsill, is shown below


It is clear that coverage to the north in this situation is very sketchy, and to the west very poor due to having to also pass through the bulk of the neighbours property as well. The best coverage area, both for high altitude (red, purple) and low level (greens) is unsurprisingly to the south-west, this being the visually least obstructed view from Sams window.

I need to say many thanks to my old colleague Mike, who has supplied me with another Raspberry Pi SBC for Sam, to replace the one I am pushing into service for this project. Sams Pi is a model B+. I expected the one from Mike to be either a B+ or one of the older models, but to my great surprise he's sent a 3B! This is the current model, which includes WiFi, and is faster and has more RAM than the B+.  Im sure Sam will put it to good use. Mike also sent a Microbit SBC, a device I had never had my hands on, but Sam has used at school. And, if all that wasnt great enough - my Pi Zero W was delivered as well! Lots of great embedded processing options available to us now!

Whilst all this has been going on, ive also been building a 1:72 scale model of a Sopwith Camel! Ive just put the undercarriage on, which just leaves the upper wing for tomorrow!

In my previous post I showed a layout plan of the ADS-B system proposal. One thing that occurs to me is that since the system will be installed in a plastic tube, and the electronics mounted on a board slotted up the middle, there is no reason to try and fit all the electronics on the same side of the carrier! The carrier board effectively divides the tube into two semicircular spaces, so the Pi and RTL could go on one side, and the USB splitter, PoE splitter and Buck Converter on the other.



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Mast-head ADS-B system - layout

More for my own purposes than anything else, just so I get my thoughts fully straight over what is required to be included in the systems radome, I have drawn up a diagram of the internal arrangement of the project

The antenna represented is the 1090MHz ground-plane. Although this has no dBd gain, it is however compact and effective when mounted clear of obstructions. The diagram only shows the necessary electrical connectivity, it does not in any way represent the hardware challenges involved.

At present, with the current test bed setup and its windowsill mounted antenna, I am running a data aggregation for 24h, to create what is termed a 'splat' - a graphical map based representation of the antennas coverage. I will post up the result of this once aggregation is complete.




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Wednesday 21 February 2018

The Raspberry Pi Range

No real reason for this post other than just to show the full range of Raspberry Pi computers. Im not gonna list the specs or anything. You can find them yourself online.


The original type A, the 2nd generation A+, and the B range


The 3, with WiFi etc


Not commonly seen by experimenters or educators, the computation unit is available without the peripherals



And the latest of the range, the Zero and Zero W


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Antenna 'Master'!

Whilst looking at images for ADS-B antennas this evening on Google, I spotted my own groundplane design with the hairpin match, but it wasnt a link to this blog! It was this discussion here https://discussions.flightaware.com/t/built-my-first-antenna-and-doubled-my-coverage/15770/241 where my antenna was discussed with the mention that it was built 'by a master'!

Sadly not! However, it has prompted me to look at how to use my spectrum analyser and tracking generator to test these antennas, since my antenna analyser only goes up to 160MHz! Looks like I need to get a directional coupler!



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Tuesday 20 February 2018

Plans afoot for Mast-head ADS-B system

The Raspberry Pi 2B based ADS-B receiver system has now been operating succesfully for over 24h, feeding data into the 360radar servers, and so I am now an official contributor and have my log-in's for access to the system.

So the next task is to work to rebuild the receiver system into a self contained system that can be mounted in its entirety at the mast-head, in order to gain the clearest view of the sky, for the furthest range, and at the lowest possible signal loss.

There are a number of difficulties with this, but principly they come down to power feed and data feed.  WiFi could be used, and indeed I have ordered a Raspberry Pi ZeroW to play with this option. The Pi zeroW is a smaller board than the Pi 2/2B or 3, but with less physical connectivity, it only has one USB micro port, unlike the 2B with its four standard USB sockets, and it has no Ethernet port. But it does have on-board WiFi and Bluetooth.

The power feed is the other issue. If using WiFi, then just a DC supply is needed. But the cost of suitably rated DC cable is no cheaper than exterior grade CAT5, and Ethernet would be a more reliable data connection than WiFi (and more secure). This brings up the possibility of using PoE (Power over Ethernet) as a convenient means of supplying the system with power.

I did briefly toy with an alternative board, the Orange Pi, as this is smaller than the R-Pi and could apparently do PoE 'natively'. Sounded good, but the chipsets are different which would have meant much difficulty in compiling the code. This idea ive abandoned once I discovered that the 'native' PoE was simply LAN pins 4 and 5 being available at solder pads. No buck converter or low drop-out 5V regulator is provided, meaning that to provide any meaningful PoE capability I would have to add a Buck Converter anyway! So its easier to stay with the R-Pi and use PoE injectors/splitters.

A colleague has sent me another R-Pi, not sure which model as yet, in order that I can release Sams 2B back to him, rather than embed it in the system. Many thanks Mike! Im looking forward to receiving this unit and seeing what modifications are needed, if any, to my plan.

So, on then to the plan! The plan is cunning... and simplistic. The R-Pi, RTL dongle, Buck Converter, and Antenna, will all be enclosed within a suitable weather radome. Lets look at the total system, from air-side to data link side -

The antenna, which is built on the body of a chassis mount BNC socket, is connected via a BNC patch lead to a BNC to MCX pigtail cable. To reduce losses in future I may replace the patch lead with a BNC-BNC adaptor, or change the BNC to MCX pigtail, which is a chassis BNC socket, to one with a BNC male flying plug.

The MCX connector plugs into the RTL SDR dongles antenna socket. The dongle will be removed from its plastic case and mounted bare, with its chip being fitted with a heatsink. So much for the RF side. Now the fun starts...

The RTL dongle is power hungry, ive measured its current draw at 280mA. This is more than really sensible for the R-Pi's USB ports. So, a Y-splitter cable, with two female and one male USB connector, will be used to seperate the R-Pi's USB port and allow a higher current power feed. The RTL dongle will plug into one of the female connectors, and the male connector into the R-Pi. The remaining female connector will have a USB break out module inserted, which allows me to make direct connections. To this will be connected a short microUSB plug cable, Vbus and Gnd only, this is the power feed to the R-Pi. Two more slightly heavier gauge wires will connect Vbus and Gnd of this break-out board to the output of a Buck Converter module. There should be no need to isolate the Buck Converters supply from that of the R-Pi's USB port, but I may do so anyway, this should be just a case of lifting the appropriate polyfuse on the board, or otherwise isolating the boards 5v rail from one of the USB sockets.

So thats the RF and local system power sorted. Now for the data link and PoE.

A low cost PoE splitter will connect the incoming CAT5 cable to the R-Pi's Ethernet port. The 2.1mm DC socket of this splitter will then connect to the input of the Buck Converter. This I 'might' do with a proper 2.1mm DC jack, if I can be bothered, or I may cut the connector off and hard wire it to the module. It probably doesnt matter. Its probably sensible to add a fuse at this point though.

And that, apart from a suitable waterproof cable gland, a sturdy radome and some pole mounting hardware, is the head end system in its entirety!

All that remains then is the 'interface' end - where the system connects to the LAN and hence on to the internet. This is really very simple. The other half of the PoE pair - the Injector - will connect between the CAT5 cable run and the router. A suitably rated DC power supply then feeds into the injector, which feeds this up the unused 4,5/7,8 cores of the CAT5 cable. Here we have to account for the resistive losses of the run length, and the current maximum ratings of the cable, which is 577mA per core.

At the head end, we want to be able to provide a minimum of 10W. As this is a 5V system, that means 2A. Clearly this cant be done within the cable rating even ignoring resistance loss. This of course is why we have the Buck Converter!

As we have two cores to carry supply, we have a maximum current capacity of just over 1.1A. But i'd rather derate the cable to no more than 500mA per core. Using a 12V supply we can have 416mA per core, even better is to go up to 24V or even, if possible 48V, where we would have little over 100mA per core, for a 10W power total. So anywhere between 24-48V will be ideal, depending on what power packs I can get my paws on. Ideally, a mod to the Router will be made to allow the router and PoE all to run on just one efficient PSU.

So all the necessary parts are either in stock or on order, other than a PSU, and a suitable housing. I suspect however that will end up being PVC pipe, as I can get suitable end caps etc, and it will all seal nicely.

In the meantime, while I await delivery of the parts, I have a 1:72 scale Sopwith Camel to build!

Sorry, no pictures with this post! But hey, have £50 on me -

On each blog post  I will be including the following link -
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Sunday 18 February 2018

ADS-B reception again

Its been some time since I played with receiving ADS-B signals from aircraft, but with the prospect of being able to track military flights in return for contributing data, I looked again at the 360radar website.

In order to contribute, you of course need to be able to receive, decode, and upload the ADS-B 'squitters'. The easiest way to do this for us was to make use of one of the RTL SDR dongles I have, plus Sams Raspberry Pi 2B single board computer


The 360radar website contains all the instructions needed to install the necessary software and get the system working, so between me and Sam we followed this and soon had decoded signals from a slack handful of aircraft using the dongles crappy stock magmount antenna stuck to the top of a Horlicks tin.

The next job then was to improve the antenna. I decided on  a simple 1/4 wave ground-plane design, but utilised twelve radials over the normal four, the resulting ground-plane at the frequency in question, 1.09GHz, being to RF all but solid. This antenna was built around a spare panel mount BNC socket

What was awkward was soldering the elements on! A 45W iron is not quite powerful enough for the job! It worked, but was hard to do. Ive ordered a 150W iron for any future heavy tasks like this!

With the new antenna just held close to vertical temporarily the resulting increase in received aircraft was astounding! from around 5-8 to 50-60!


However, since all this was rigged on Sams windowsill, it couldnt stay this way. So I had to create a stand to mount the antenna on, so that it can remain in use for some time, until we get the system compact and contained for mast-head mounting.


Theres nothing flash about this mount. Its literally a bit of PVC conduit, rammed into a hole in a block of wood, with a BNC to BNC patch lead in it!


And here it is with the antenna mounted and the receiver connected. It keeps it vertical, and more to the point tidy. The screenshot below shows a moment in the decoded aircraft signals using this antenna.


More work is required, for a start I need to let Sam have his R-Pi back!  So the software will need to be installed on another R-Pi that im arranging to obtain, and the whole thing - antenna, receiver and computer, mounted into a weatherproof radome for installing on the roof apex mast. I plan on running another length of external grade CAT5 cable for this, and making use of PoEt (Power over Ethernet), so I also have some PoEt adapters on order.

Ive received the amplifiers that I intend to use with the HB100 radar modules as well, so will need to fit that experiment in soon.


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Friday 2 February 2018

First Experiments with HB100 Doppler RADAR Modules

 Cor blimey! Aint it cold!!!

These past few days here have been enough to freeze the balls off of a brass monkey! (although monkeys were never made of brass for this exact reason - if you dont know what a 'monkey' is, research naval gunnery in the 18th century!). If your finding that your gas bill is extortionate this time of year, take a look at the link at the bottom of this page!

The HB100 Doppler RADAR module is the modern equivalent of the old X-band Gunn diode modules that many of us used for 10GHz WBFM back in the 80's and 90's. And they cost very little. I have two of these to experiment with.

The ultimate goal of course is to use them for 10GHz WBFM amateur radio, but they are somewhat harder to use in this manner than the old Gunn modules were.

Instead, as a project for my son who is well into his coding, we are looking at a simple RADAR speed gun project. To this end, I had a little play with one yesterday.

Nothing very special, and no pictures im afraid for this post. Simply a test that they do in fact work. I took one of the modules and connected its IF output to the 'scope, and gave it a clean regulated 5V supply. The output is extremely low level, we are talking just a handful of mV here, and is a variable audio frequency, dependent on the speed of the target, which in this case was just my hand being waved about! But - I could detect an output waveform.

Next step is to add a suitable IF amplifier chain to bring the output level up to around 3V or so, suitable for shaping and feeding into an Arduino.

Also yesterday, I finally joined the Milscanners group and programmed by UBC-125XT scanner up with the UKs military airband frequencies that are most likely to be receivable from the shack. Im quite surprised to be able to hear aircraft at low level all the way down to RAF Cranwell, and extremely pleased to be able to hear at good level aircraft at the Donna Nook gunnery range. The trick now will be to identify any frequencies that I just cant get any traffic on and remove them - as there are still around 60 air defence channels I want to add but have run out of memories!



On each blog post  I will be including the following link -
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This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Sunday 28 January 2018

Converting the LED Emergency Lights

Well the Buck Converter modules arrives a couple of weeks ago, but its been too cold to be in the workshop for long, so ive only just got around to progressing this,

The original plan was to remove ALL components from the original boards, both through-hole and SMT, except for the Constant Current Driver. This proved to be impossible as the SMT parts are all glued on! So instead, I decided to isolate the driver IC by milling away the track and the SMT parts in the area around it!

This first board you can see the result of attempting to remove the SMT parts with the heat gun!
I also decided to keep one of the fuse holders in place for the 12v feed to the Buck Converter. Using the original track on the board allowed short bridge wires to be used to connect the module, with a bit of hotmelt glue to hold it in place


The 10 turn preset for setting the output voltage seems to have far too many turns than required - it took a fair bit of 'screwing down' to reach the 3.9V required. Next step is to connect this to the Driver IC, add any other required parts (bypass capacitors etc), replace any poor output LEDs, and wire it all up. An on/off switch will be added to the casing.

Although I do have a lot of 5mm white LEDs, Ive also started to salvage the ones in my now failed Black & Decker LED worklight.

As Sam is becoming a very competent programmer, we've also decided on another Arduino project. As I obtained a couple of HB100 10GHz doppler radar modules some time back, we are going to build a speed gun!



On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!