Friday, 31 January 2014

Wireless Woes

It was always my intention when I had my workshop/shack installed to install a permanent wired network link, however I never did and now it would prove a logistical nightmare.

When I first got wired up to the Internet with Diamond Cable back in the late 1990s it was via a second telephone line fed in to the 'computer room/study' which in reality was the small 'box/bedroom' at the front of the house.

Diamond Cable became NTL/VirginMedia and with the introduction of proper broadband the Cable Modem naturally got installed in the same front bedroom. I have always had several computers networked together but mostly in the same room via cables.

I eventually got a router with wireless capabilities the ubiquitous Linksys WRT54G and gradually more and more devices have been linked wirelessly. Laptops, smart-phones, a modified original X-Box running XBMC to play videos on the TV, Netgear MP-101 media player and a Nintendo Wii. More recently my new Canon printer and Samsung SmartTV are now connected to the wireless network.

Over the years I have acquired different routers and access points but I kept going back to the WRT54G as it didn't have as many compatibility issues and since the firmware was upgraded to Tomato and has proved to be rock solid. It covers the house reasonably well, but not so well at reaching the shack in the back garden, most wireless devices just give up. If they can see the network they seem unable to maintain a link.

When I fitted out the shack I was forced to find a solution. I could have gone out and got a wireless booster to fill the blackspot, but as I had a collection of various wireless routers/access points I investigated possible solutions that didn't involve any expenditure. I made the assumption that the superior antennas and design of the RF circuits in the access points would overcome the range issue. I was sort of correct and in the end I managed to get a Netgear WNR2000 configured using WDS to connect to the main house wireless.

Sadly the WNR2000 is quite frankly rubbish and often needs to be rebooted to get the link established, when it works it is great but too often it doesn't! The other major issue was the implementation of WDS will only work with WEP encryption.

WEP is potentially insecure, I was getting more and more concerned about this so when I finally deprecated the last remaining WEP only devices in the house I have switched to WPA, ironically I had hoped to use WPA2 but alas some devices are WPA only!

Doing this has broken the shack network so I was back to square one. During the recent forced clearout I found a forgotten Buffalo router, mind you looking back you can see why I had forgotten it.

A quick check and joy of joy it turned out to be a WHR-HP-G54, a device supported by the Tomato firmware, so was duly flashed up to version 1.28

I have now got it setup as a Wireless Ethernet Bridge and seems to be working well (I may have been a bit harsh on Twitter back in 2009!) and seems more importantly to be relatively RF quiet compared to the Netgear WNR2000 A good result!

Now I have some connectivity should make next weeks 144MHz UKAC contest a little easier, if I can the 2m antenna sorted and work out how to use the logging program.

Oh and the picture at the top? From South Park "Over Logging (or The Day the Internet Stood Still)"a classic episode!

Wednesday, 29 January 2014

My first contest

Last night I attempted my first contest, the RSGB 50MHz UKAC

I am a complete novice at using HF, in fact I am a complete novice at transmitting anything!

My Chinese Baofeng handhelds have pretty much collected dust since getting my licence. However with the purchase of the FT-857D I must, despite my trepidation, step up to the microphone.

I had hit a snag when testing out the new radio, my antenna was showing high VSWR on 6m, even with the ATU I was struggling to get it to 2:1, therefore I decided to construct a simple dipole and sling it up with an ugly choke 'balun' I had constructed.

Due to some unexpected delays I was running out of time but eventually did manage to get something up, it was only around 2 meters off the ground and the VSWR still wasn't ideal, but I was ready.

At the appointed time, well nearly an hour late I started turning the dial and was met with a load of static, wasn't hearing anything! This continued for a quite a time then suddenly I started hearing "CQ Contest  CQ Contest" I listened in for a while to try to get the gist of the exchanges, wandering up and down the band.

Then I decided to have a go at a QSO, giving my callsign out, I waited nothing! "QRZ CQ Contest CQ Contest" another go.. still nothing.. and so on..

Changed frequency to another stations, tried again and I was heard, but they couldn't make out my call sign despite several attempts.. another change of frequency and the same results.

Now I know I had only got it set a 5W, the lowest I can till I get some confidence in my set up and am not going to damage anything! But I was a little disappointed, but I persevered until suddenly I was in the middle of my first contest QSO and my brain turned to jelly..

Thanks to M0MDY and his patience and prompting I successfully completed the QSO, details suitably written down. I carried on with no luck and called it a night just after 10pm, and went back in the house and manually entered the details of my solitary contact on the RSGB Contest website

Checking this morning and there I am at the bottom of the list, but not the very bottom, with a whopping 48 points.

Roll on next week, it is the 144MHz UKAC and I have a proper 2m YAGI... just got to work out how to mount it up on the poll and how to rotate it..


Sunday, 26 January 2014

All systems go...

Excellent service from Waters and Stanton, Radiozing and M0CVO Antennas meant my FT-857D, PSU and HF antenna arrived the day after I ordered them. They have however sat in the boxes while I have struggled to reorganise my workshop/shack after the Christmas chaos.

I have disposed of a lot of junk being quite ruthless to reduce the clutter and have completely changed the layout, increasing the size of the desk and putting it on the other side of the room next to the workbench, which is much more logical.

The new look operation centre
I have finally summoned up the courage to drill a large hole in the wall to allow the antenna coax to enter properly, previously it has been done by squeezing it around the door!

Unfortunately the weather this weekend has been horrendous, yesterday I planned to erect the antenna but gave up following the intense squall which hit in the afternoon with thunder, lightning and hail! Today hasn't been much better with heavy rain for most of the day, the rain did finally eased off so I managed to erect a temporary mast with the 144/430MHz collinear on the top and the HF antenna underneath.  I know this isn't ideal as the mast is metal and may affect the HF, but seems okay. The forecast for the next few days is also a bit worrying but the mast is guyed at two heights so should be secure.

The antennas, with the stormy sky behind
I have literally just turned on the FT-857D and had a quick listen on the bands, it is very daunting for this first timer! The first thing I have worked out is how to drop the power output, current set a 5W for HF and VHF/UHF

I have a power/swr meter suitable for HF/VHF and UHF I purchased at last years Hamfest and I have it connected in the setup, and was trying to check the SWR but it wasn't registering anything when I pressed the PTT then I realised that with SSB enabled it wouldn't!! Switching to FM and I was able to check that everything was okay... Beginners mistake I know!

Now off to read the manual..

Tuesday, 21 January 2014

Got a proper radio, well it's on order!

Well I've finally done it..

I have ordered my first proper 'rig' It is a Yaesu FT-857D a nice small, portable/mobile unit that will give me access to the HF and 6m/2m/70cm bands in all-modes. It has took a while since I first identified it as potential purchase but thanks to some generous Christmas presents I now have the sufficient funds and following several recommendations have decided to take the plunge and ordered it from Waters and Stanton

She is a beauty!

I have a decent 7A PSU, purchased last year which I am sure would have sufficed for 10W maximum operation however I decided to also purchase a MAAS SPS-30-II 30A(35A peak) PSU. It was a good price from Radiozing and offers plenty of power for anything I am likely to run in the foreseeable future, and from the pictures and reviews seems to be built like the proverbial brick out-house. As well as the main connectors on the back it has spring clip terminals on the front as well as a cigar lighter type connector. Dual meters showing V/A and can be used in variable mode from 9-15V or fixed at 13.8V 
This is the beast!
I have also ordered one of M0CVO Antennas highly rated HW-20HP off centre fed dipoles as a starting point for HF. The antenna works in 6 bands (20, 17, 15, 12, 10 & 6m) without needing an Antenna Tuning Unit (ATU) which is one thing I haven't purchased, however Nigel(M0CVO) Chairman of SKARS (South Kestevan Amateur Radio Society) and owner of M0CVO Antennas has kindly offered to loan me an ATU in the short term.

Delivery should be later this week and I suspect I have a large learning curve ahead of me as I hit the airwaves! If you should hear me please be gentle..

Thursday, 16 January 2014

FUNCube Decode Issues

I had a pleasant surprise last week at the AGM/Prize giving evening of the South Kestevan Amateur Radio Society (SKARS) being awarded the Most Promising Newcomer!

I also had a small write up in Tim Kirby's (G4VXE) VHF/UHF section of the February issue of Practical Wireless about my I-Cube1 reception which I have mentioned on here before.

I haven't progressed very far with my Arduino projects. There has been a set back in the plans to build and use an Ultimate3 QRSS kit. I had incorrectly assumed as it was a kit being sold commercially that it would satisfy my foundation conditions. However I have been advised that Foundation license holders may use radio equipment constructed using commercially available kits which satisfy IR 2028 which is all a bit vague and woolly, but I don't believe this particular kit does.

There is a simple solution, I will just have to take my intermediate assessment and exam at the first opportunity!

I have been doing a little WSPR spotting, getting some nice spots.

Over the Christmas/New Year period I have neglected the FUNCube-1(A073) satellite and was slipping down the telemetry upload rankings, sad I know!

Now I have got back the upstairs 'shack' I set up my original FUNCube Dongle on the laptop running the dashboard application continually to capture/decode the telemetry using the loft mounted discone. I took the opportunity to upgrade to the latest version 8.14 of the dashboard software, however something was amiss when checking the statistics I was only adding the odd frame here and there, sometimes not making a single decode during the high power daylight passes.

I switched back over to the newer FUNCube Dongle PRO+ running my main PC, which I had also updated to the version 8.14 dashboard and saw the same behaviour, rather than getting daylight decodes of 30+ frames I was just getting the odd 1 or 2.

My first thought it was an antenna or interference issue, but checking the SDR waterfall the signal is still very strong with little QRM. Suspecting a software issue introduced by the update I checked the FUNCube forum and found a thread which appeared to confirm my suspicions.

I have a number of discussions on twitter with various people including David Johnson (G4DPZ)  an AMSAT-UK Committee Member and one of the developers of the FUNcube ground segment. David kindly performed an analysis of one of the passes yesterday where I managed just 2 frames, and from the results it does appear to be an issue at this end, rather than issue with the spacecraft.

I have uninstalled v8.14 and put back on an earlier version of the dashboard (v8.09) and thanks to a windows update last night have also performed a full reboot!

There was a good pass this morning at 62 degrees maximum elevation (to the east), followed by a lower pass at 22 degrees elevation (to the west so not so good) and it seems things have improved managing 68 and 17 frames respectively. So could this be an issue with the latest dashboard?

If anyone has suffered similar performance fall-off, or indeed not suffered any issues then please add some feedback to the FUNCube forum.

My copy of Radcom arrived but didn't have much time to read it..

The culprit! ;-)

Friday, 3 January 2014

Another Day Another Arduino Project

Yes another day, another Arduino project (seriously this is a great development environment)

As I mentioned in passing yesterday I have a number of Arduino based projects buzzing around in my head. One of them is to produce a satellite antenna pointer/indicator.

I have used an Android AR tracking solution before (flaky at best) and can see the relevant information in Orbitron or SatPC32 to know where to point the antenna but it is difficult to see a PC screen when stuck out in the middle of the lawn!

My idea is this, I will make a large tripod to which I can attach appropriate antenna as I need, then during the satellite pass it has indicators to show where to point the antenna manually.

I envisage the azimuth indicator to be a large horizontal circle with 36 LEDs positioned at 10 degree intervals, the elevation will be a quarter circle with 20 LEDs positioned at 5 degree intervals. Then during the pass the appropriate LEDs will light and assuming I keep the antenna aligned to these I should in theory get the best signal... Crazy??

Yes I know I could make or buy an azimuth/elevation rotator, eBay is full of low speed high torque geared DC motors with auto-stop/hold and numerous software solutions exist to drive them but this would require a bit more engineering and isn't something I can easily fabricate at the moment. My contraption would be much more rustic being made of rough cut timber!

Bright LEDs are ridiculously cheap and controlling this number from the Arduino will require the use of multiplexer drivers. The popular ones are the MAX 7219/7221

I won't go into the details of exactly what multiplexing is, other than to say that each display element (LED) is driven one at a time but by switching the electronics at high speed combined with the persistence of vision make the viewer believe the entire display is continuously active.

This technique can be used for individual LEDs, an LED grid matrix, or for 7 segment displays. Last night I successfully got a MAX7219 based 8-Digit 7-Segment LED module working.

The next stage was to investigate how an Arduino could calculate the appropriate azimuth and elevation data. Thankfully a library already exists qrpTracker (code is here), within this library is a port of the Plan-13 algorithm first written in Basic by James Miller G3RUH in 1990, subsequently ported to C by Edson Pereira, N1VTN and further updated by Howard Long, G6LVB.

Plan-13 processes keplerian elements, time and (optionally) observer location, and uplink downlink frequencies; it outputs satellite latitude and longitude, azimuth and elevation, and Doppler shifted frequencies. At the standard 16 MHz Arduino clock speed, this code can complete these calculations in approximately 30 ms. This code is reported to be highly accurate, if provided with proper data.

The important data are the observer location (longitude/latitude) and the current time. Step forward my well used GPS module which once lock is achieved can supply that data.

The next is get the appropriate up to date Keplerian twin element sets (TLE) and extract the appropriate information from it and pass that data to the Plan-13 functions.
The standard TLE follows the following format

You need to extract the Epoch Year/Day (including partial data), Inclination, Right Ascension, Eccentricity, Perigee, Mean anomaly and Mean Motion for a calculation (drag/orientation aren't critical) For the moment I have just extracted this manually from the latest TLE and entered it directly into the program.

After just an hour or so of research and programming I have the LED displaying the current azimuth and elevation of the FUNCube-1 satellite (AO73) based on the current position and time derived from the GPS!

The first four digits is the azimuth, the second four the elevation.

The next stage is to sort out the LED disc indicators, build the antenna tripod and formulate a method to upload the appropriate up to date TLE files from the PC which can be stored in the EEPROM of the micro-controller.

Thursday, 2 January 2014

Arduino, WSPR and AD9850 DDS experiments

Happy New Year!

Christmas is thankfully behind us so I can get back to what I enjoy doing once I have reorganised my workshop.

As you know I am currently developing a potential High Altitude Balloon (HAB) project and have been experimenting with the Arduino microprocessor platform and have constructed a basic prototype.

With the arrival of the GPS module(s) I have had it successfully working and even took it out for a test walk in the local area, receiving the data and uploading it to the UKHAS habitat system.

This project has revitalised my interest in 'hobby electronics' and I have ideas for a number of other Arduino based projects and have been splashing out on components from eBay. Just before Christmas I purchased an Arduino Mega board, this has more I/O pins than the current Uno and specifically some extra hardware serial ports.

Do any internet search for Arduino based amateur radio projects and it will results in numerous mentions of projects using ultra cheap DDS modules based on the Analog Devices AD9850/AD9851 chipsets.

DDS means Direct digital synthesiser and is a type of frequency generation which can be used for creating arbitrary waveforms from a single, fixed-frequency reference clock. Read the Wikipedia page for more details.

In a nutshell the AD9850 is a chip that under microprocessor control can produce a sinusoidal wave from about 1hz to 40mhz. In other words it is an accurate microprocessor controlled VFO (Variable Frequency Oscillator) or signal generator.

VFOs are the main building blocks of radio receivers and transmitters, so not surprisingly a lot of projects have utilised these modules, rather than the traditional means. Intrigued I ordered a couple of these modules for the pricey sum of £3.50 each!

Using information on George Smart's (M1GEO) website and Simon Kennedy's (G0FCU) blog  I quickly had a simple WSPR beacon running!

The Arduino uses the GPS module borrowed from NERD-1 for accurate time and then controls the output of the AD9850 DDS to generate the WSPR signal.

Before anyone panics I know at the moment I only hold a Foundation Amateur Licence so the construction of homebrew transmitters isn't allowed. This 'beacon' has no power amplifier and the antenna consisted of an inch or so of wire on the DDS output. I was able to verify the operation using my SDR receiver in the same room.

Construction of commercial kits is allowed under my licence so I have ordered a Ultimate3 QRSS kit from Hans Summers for the pricely sum of £17.50! This uses the same DDS module and same microcontroller as the Arduino.

In the meantime there is also more information and ideas on Eugenr Marcus' (W3PM) webpage about the use of these DDS modules, including making frequency reference sources and calibration using the GPS module.

My new year resolution is to get my Intermediate Licence as soon as possible..  but it has been great to get down to some proper experimenting...