Magnetometer Problems

Well, I have been testing the Magnetometer over the last couple of weeks and was hoping to report some success, however there is a basic problem which I cannot resolve.

A typical graph of the output I am getting is shown below.

The approx. 1280mV line is the initial output from the magnetometer which should then change dependent on changes to the magnetic field, however what seems to be happening is the output jumping to 1800mV (and superimposed on this level there does seem to be a fluctuating signal) before being pulled down to the initial output voltage, almost as if the device is being periodically reset and held at the reset voltage.

(The change between 13:30 and 14:00 was me checking the wiring again, switching off and on etc.)

There seems to be no logic to the frequency of these changes. I have checked and double checked all wiring, the circuit board etc. but cannot find any cause for this problem.

Not sure where to go now.

St Jude's Day Storm

A strong storm over the south of the country overnight and early this morning, which has been given the name of the St Jude's Day Storm.

No serious damage, however I lost my Off Centre dipole wire antenna after a branch from one of the trees in the garden came day.

On checking the garden I found this:

Repairs will have to wait until the weekend.

The strongest gust of wind that my weather system recorded was 37mph which is very low considering gusts of 70 to 80mph were recorded across the south of the country.

The wind speed is measured slightly above the ridge of the roof as shown in the following picture:

However, to the south (left of the above picture) we have a small wood with lots of tall trees. These have a shielding effect so we do not often get the full force of the wind so I always register lower wind speeds

The following picture is a screen copy from my weather system which shows the change in pressure as the storm passed through (top graph):

The lower graph shows the rainfall (red line) which reset at midnight, showing the large amount of rain yesterday evening and this morning. The green line in the lower graph shows temperature. Interesting to note the fall in temperature coincides with the increase in air pressure in the top graph.

JT65 Activity This Evening

I managed to spend some time on the radio this evening for some JT65-HF activity on 20m. Put out some CQ calls and worked the following stations:

DL7UM, KS3K, NW9T and 9Y4NW

9Y4NW in Trinidad and Tobago is I think a new one for me so many thanks for the call Neil.

I was called by KY7S in Seattle but unfortunately after the first call I could not decode anything more, so could not exchange signal reports.

Magnetometer Installed

Dodging the rain over the weekend I installed the Magnetometer in the garden.

The box with the sensor is buried below ground. The reason for this is to minimise the impact of temperature changes. I have found the sensor to be very sensitive to changes. In the garden also tries to distance the sensor from any moving metallic objects which may impact the readings.

The following shows the sensor box in position:

The compass on the box is to ensure there is correct alignment of the sensor along the east - west axis.

The box about to disappear (I did remove the compass before filling in!)

The control box with the processing electronics is mounted on a fence post in a water tight box.

This is connected to a PicoTech Enviromon system in the shed that monitors the output voltage and records the data. Software on the computer produces an updated graph every few minutes.

I will post some sample graphs to show the results. Hopefully this will work.

No Wonder I Was Getting A Poor SWR !!

A week ago I tried to tune my FT2000 on 40m via the external SGC Smart Tuner but it would not tune up and the meter on the FT2000 was showing an infinite SWR, not good!.

This weekend I was able to get outside on Sunday despite really bad weather and this is what I found:

No wonder it would not tune up.

The cable usually breaks where it passes through the insulator at the 90 degree bend in the inverted L. As shown in an earlier post, it is this insulator which has been up for so long that the majority of the insulator has been engulfed in the branch. It was originally loose, held by some rope around the branch, this was 14 years ago when I first received the M5LMY licence which meant I could get on the HF bands.

Over those 14 years, the branch has gradually grown around the rope, then the insulator so that now more than 50% is buried within the branch. In another 5 to 8 years I guess it will disappear altogether.

The cable breaks at this point as there is no flexibility with the insulator so the cable is rubbing on the fixed insulator and wears through.

The weather yesterday has really bad. Raining for much of the day with some intense bursts along with thunder and lightning. The following is from my weather station, the red line showing rainfall:

In total today we had 22.4mm of rain.

Conditions seem to be improving on 10m recently. The following is a snapshot of the map from wsprnet.org yesterday evening showing where my signal had been heard.



This is running 5w to a very small random length of wire, hidden within some conifer trees, fed via an auto tuner.

Not much activity recently, mainly due to work. One JT65 contact with K8QZ on Friday evening.

A Day of Activity

It was grey and overcast here in the south of the UK yesterday so a good day to play radio.

It was Railways on the Air weekend so there were a number of special event stations to work. I managed to get 13 stations in the logbook.

I spent some time during the evening working JT65 on 20M.

The above is a snapshot of my screen showing an hour's activity during the evening. For this mode, I use my Kenwood TS2000 running into an M0CVO HW-40HP antenna. This system works really well on all bands from 40m through to 10m with the internal ATU on the TS2000.

JT65 is my preferred data mode at the moment. It supports long distance working with low power I get called by the type of DX that I could never work using SSB.

MV5LMY QSL Cards

I used the "V" prefix earlier this year which was issued to mark the centenary of the RSGB. My call sign was MV5LMY. The RSGB also designed a couple of special QSL designs, I ordered one of these and have now received my pack of cards ready to complete details and send:

This is the "Art Deco" design. I selected this design as it is very similar to my first QSL card when I was G8LMY back in 1977. This original card also had a red map of the country to the right of the card.

Now just need to write them all and send via the bureau.

A Weekend of Bad Weather

The weekend weather here in the south of the UK has been terrible. Grey sky, rain and winds. The following satellite picture from Sunday gives a good view of the weather we were under:

This is the NOAA 19 pass from Sunday at 12:55. Ireland was generally cloud free and the north of the UK had some breaks in the cloud, however a large sweep of cloud over the south of the country.

Another good satellite pass from the north of Africa to Iceland. Not bad for a loft mounted pair of crossed diploes.

Update on Magnetometer Construction

Progress has been slow with Magnetometer construction, however I now have the main PCB completed and installed in the box that will be installed in the garden.

The photo below shows the PCB installed:

 

The wiring from the circuit board is for:

• Input Power
• Power to the sensor and output from the sensor
• Reset
• Sensitivity settings
• Output

The space on the left is for the Arduino that will be used for remote control of the Reset and the Sensitivity settings.

The next stage of the project will be to set up and test.

The box will be installed on a post in the garden with a cable running to the sensor which will be installed at the bottom of a hole in the ground to hopefully limit temperature drift of the sensor.

A second cable will run from the box to the computer shed where the data logger is installed along with the 12V power supply. An Ethernet cable will run to the Arduino.

Subject to weather, the system should be installed in a couple of weeks.

New Project - Magnetometer

One of my current construction projects is a Magnetometer based on a kit from Speake & Co using their FGM-3 Magnetic Field Sensor.

The sensor detects changes in the Earth's magnetic field. This is changed into a DC analogue output which will vary dependent on changes to the Earth's magnetic field.

The sensor is very sensitive to local variations in the magnetic field and also to temperature.

I have tested the system before but always found temperature stability to be the main problem. With the new kit, I am aiming to reduce temperature change by separating the FGM-3 sensor from the main electronics by burying the sensor in box a few feet below surface level where hopefully temperature will be more stable.

I am also using an Arduino so I can have remote control of the sensitivity settings and the reset switch to make it much easier to manage the impact of any major magnetic or temperature changes.

The following picture shows the kit of parts as received, ready for assembly:

The kit is reasonably easy to construct and consists of the FGM-3 sensor and a small circuit board that hosts the electronics to take the output of the sensor and converting to the variable DC voltage.

No Surface Mount Devices so still within my soldering capabilities!

So far I have installed the sensor in the box that will be buried. This is shown in the picture below:

The box is a small waterproof box, in which I have installed a length of plastic cable trunking. This is perfect for holding the sensor which is secured with a couple of cable ties. The trunking will be glued to the sides of the box and the cable entry hole sealed ready for burying.

The cable is Ethernet Cat 5 which should work fine for this application. This will run back to the main box which houses the electronics.

Next stage is to construct the circuit board and test. I will update as the project progresses.

New QSL Cards Received From The Bureau

An envelope arrived from the RSGB QSL bureau a couple of days ago with a new batch of cards for contacts over the last few years.

I really do like receiving paper QSL cards, just does not feel the same with the almost instant Internet alternatives. Even when a card is received several years after the original contact it brings back memories of the time I made that contact and what I was operating.

The following are scans of the latest batch of cards. If yours is amongst them, many thanks for sending the card. You should receive mine as I automatically send a QSL for all new contacts and new bands.

The Last Day Of Summer?

The following picture was received from NOAA 19 on Thursday 5th September. A really good pass from North Africa to Iceland using my cross dipoles in the loft of the house.

The weather at ground level was really good with clear blue sky and in London where I was for the day, the temperature reached 29 degrees centigrade.

The following day, there was a 10 degree temperature drop, cloud and some rain which has continued today, Saturday 7th September.

I suspect that this was the last day of summer and we are now moving into Autumn with Low Pressure from the Atlantic bringing wind and rain.

Checking My Inverted L Antenna

I have two antennas at home, an off centre dipole and an Inverted L. The Inverted  L has been up since the year 1999 when I first received the M5LMY licence and could operate on HF.

This antenna is fed at the base of the vertical section by an SGC auto tuner. The vertical section is about 5m tall and the horizontal section about 7m long with both sections strung within some oak trees.

Had the opportunity today to check the Inverted L, the first time in a year. In the 14 years that this antenna has been in use, the insulator at the bend from vertical to horizontal has become almost fully embedded within the supporting tree branch. This insulator was free when installed, held to the tree by some Kevlar rope wrapped around the branch. In the 14 years, the branch has grown and almost taken the full insulator. See the following photo:

A bit difficult to see as the photo was taken into the sun, however only the hole for the wire and a small bit of the insulator body is still free. The main part of the body and the hole at the opposite end for the supporting rope has fully disappeared into the branch.

The following photo shows the horizontal section running to the tree at the end of the garden.

The wire almost rubs against the branch in the foreground, I wanted to check that the insulation has not been worn through, however it was in good condition. As can be seen, the wire is fully within the trees.

The following photo shows the auto tuner at the base of the vertical section.

This is an SGC model SG-230. This is the second one I have had since 1999. the first failed around 2002. The replacement has worked perfectly since.

The two yellow/green wires at the base of the tuner connect to a copper earth rod, from this a single wire runs under the earth beneath the horizontal section in the air.

This set-up was originally used by my TS2000 and now supports the FT2000. It supports operation on all bands between 80m and 10m which is very good for such a small system. Obviously performance is a very big compromise, however for a simple antenna that does not stand out in the garden it work really well.

Computer Operating Temperatures

As I have a number of computers always running I built an outside shed to host these so they would not have to be in the Radio Room. These computers are receiving Eumetcast Weather Satellite data, running my Weather Station, acting as a Media Server, monitoring WSPR and APRS for good propagation conditions, running an NTP server etc.

The problem with the shed is a confined space with no ventilation or cooling unless I open the door, which I usually do on hot days but often do not remember until later in the day.

The computers in the shed have been running, with the exception of a couple of very small breaks, continuously for 5 years.

The temperature inside and outside the shed is monitored and it has been very interesting to monitor the inside temperature which can exceed 40 degrees centigrade at times.

The following graph shows a typical day from this August with the internal and external temperatures.



The external temperature always reads a couple of degrees too high as the sensor is located on the side of the shed between the shed and a fence with very little free air flow.

The graph shows very well the difference between the internal and external temperatures.

In the 5 years of continuous operation, the only failure I have had is one of the computer power supplies, no other problems despite continuous operation (and with very heavy disk usage with the Eumetcast satellite receiver), all with standard, consumer, off the shelf computer components.

I suspect being always on helps, but it is interesting how robust computer components really are.

Decoding now working - But problems remain

Following on from my last post and my JT65 problems after installing a new sound card, it is sort of fixed but I cannot find the root cause.

I tried removing the new sound card and doing a system restore to get the system back to the same state as it was prior to installation of the new card. The problem with JT65 remained, it would not switch to decode.

I also tried HRD DM780 to decode PSK, however this also was not working and could not decode, so not specifically a JT65 problem.

My next step was to switch the radio interface from the original motherboard sound to the new sound card and it worked. JT65 would switch to decode and was decoding stations as usual.

So whilst I have not fixed the problem, decoding applications do not work on the original, motherboard soundcard, they are working with the new soundcard.

What I do not understand is why JT65 would not switch to decode and why this is soundcard dependent. I assumed it was a timing function with JT65 switching to record after 49 seconds (hence the need for accurate PC timing).

The new Soundcard is an ASUS Xonar DS and the motherboard is the usual Realtek. Operating System is Windows 8.

Why Are Computers So Unpredicatble ?

Why does what seems like a simple change cause what seems like unconnected problems on computers.

I installed a new sound card today to provide a second sound device in addition to the one on the motherboard. 

Installation went well but when I started JT65, signals were displayed on the waterfall but it would not decode. The program stayed in Receiving mode all the time and would not attempt to decode. 

Tried a new installation but exactly the same. Checked all the configuration parameters but nothing that would impact decoding. 

Not sure where to go now, have done the usual Google searches but nothing similar to this problem. Have put a question on the JT65 group, hopefully someone has seen this before and can suggest a fix.

An Evening On JT65

Spent the evening on 20M using JT65 to give the MV5LMY callsign a bit of use before it expires at the end of July.

Put out some CQ calls and received a run of replies which was good. Must be the special call.

Stations worked: RU4PT, EA3GBL, DL2KWA, UT7IX, OH5CX, GM4XAW, RA1ZN, DF3NA, OE6KLG, WA4MIT, JE4CIL and W7VP.

Mainly Europeans except for the stations from Japan and the US at the end of the evening.

My signal was getting out well as shown by the following screen shot from PSKReporter:

 

This was taken just after close down at 21:30 GMT. The MV callsign comes to an end on the 31st July so just a couple more evenings of use.

 

10m Conditions and WSPR

Conditions on 10m have been very poor for some time and for this stage in the sunspot cycle there should be some improvement. Looking back on my logbook for the similar point in the last cycle I was working DX across the world, but not this time.

I run a WSPR beacon when I am at home to monitor 10m and hopefully catch any good conditions, however the following screen capture from http://wsprnet.org/drupal/ is typical of the distances I have been achieving:

 

My WSPR system consists of an IC706 MkIIG running 5W on 10m to a small Inverted L wire antenna.

 

I get the impression that the peak in the current sunspot cycle is not going to be so good.

 

Regarding recent activity, I have been on JT65 on 20m quite a bit over the last few days giving the MV5LMY call sign some activity.

 

Weather Satellite Pictures Keeping Getting Better

Another day of good weather and another day of very good APT weather satellite pictures.

The following is from the 13:05 UTC pass of NOAA 19, again with most of the UK cloud free.

It is a cropped image, however the overall duration of  the pass was again excellent and shows what can be done with a simple loft antenna.

The cloud cover coming off the North Sea onto to east coast is quite a common occurrence. It is interesting to compare what the weather is like at ground level against the satellite picture. There are many really good webcams that enable this to be done very easily. A good set of webcams on the coast of Norfolk are on the Happisburgh Lighthouse. See the following link: http://www.happisburgh.org/webcam

The whole Happisburgh site is worth a read and the village is well worth a visit. Check for the days when the Lighthouse and the Church Tower are open. Views from the top are excellent.

Good Weather At Last !

The weather for the last week has been excellent with high pressure covering much of the country resulting in very warm conditions, reaching 28C and clear skies.

As well as Eumetcast, I still receive APT transmissions from the NOAA satellites and during summer with the sun at a high angle the received pictures are excellent.

The following is the picture as received (with minor contrast enhancement) from NOAA 15 late this afternoon:

Most of the United Kingdom is cloud free and London and Birmingham stand out well as slightly darker than their surroundings.

I receive the polar orbiting NOAA satellites using a Timestep receiver which is almost 20 years old and has been in use almost 24 by 7 for all that time. The antenna is a turnstile cross dipole style of antenna located in the loft of the house which makes the duration of pass and received quality all the more surprising.

The Timestep receiver feeds audio to the computer soundcard and the audio is processed into pictures by the excellent WXtoImg.

MV5LMY RSGB Centenary Callsign

From the 5th July to the 31st July I will be operating the call sign MV5LMY.

The "V" addition to the call sign is to celebrate the RSGB Centenary. See details at the following link:

RSGB Centenary

I have been a member of the RSGB since 1976 and am very please to be celebrating the centenary of the organisation in this way.

I look forward to working you on the air with the MV prefix and will be sending special QSL cards via the bureau.

QSL Cards Received From The Bureau

I received a pack of QSL cards from the RSGB QSL bureau yesterday.

I much prefer receiving paper cards in the post, even though they can take many months, indeed years to arrive, rather than the electronic options that are available now. I suspect it is down to when I started as a Short Wave Listener in the early 1970's, years before the Internet. It was the excitement of receiving an envelope from some exotic location with a QSL card enclosed.

The following is a sample of the cards received. If yours is amongst them, many thanks. I had already sent cards off to all stations worked via the bureau so hopefully they will also be arriving with these stations.

New QSL Cards

I much prefer paper QSL cards to the electronic options that are available today. I suspect this goes back to when I was a short wave listener in the 1970's and the thrill of receiving a QSL card through the post from some exotic, far away country. These were the days prior to the Internet !

I have almost used up my last set of cards so decided to order a new batch a couple of weeks ago. I change the photo and design of the card each time I get a new set and always use a photo that I have taken. I received a parcel in the post this morning containing 1000 of my new cards. The following is the front of the card.

The photo is one of the Hovercraft used by Hovertravel between Southsea in Portsmouth and Ryde on the Isle of Wight. The photo was taken at Ryde showing the hovercraft starting back on the journey to Southsea.

I understand that this is the only scheduled passenger hovercraft service in Europe.

Good Weather At Last !

Following my comments on Friday about the very poor weather we have been having, we have finally had a good weekend. Contrast the following satellite picture received Sunday with the one received on Friday.  Clear skies at last.



© EUMETSAT (2013)

Poor Radio Conditions and Space Shuttle visit to Stansted Airport

Not much happening on the radio at the moment. Conditions have been very poor with 40m almost unusable for much of the day yesterday and not much better on most of the other bands. I just hope conditions will improve soon. 10m has also been very poor. I monitor 10m using WSPR and most of the time it is only very local stations that I see, and hear my WSPR signal. Not good.

I have been spending time recently scanning all my old photo negatives. I have a very large collection going back to when I started taking photographs in the mid 1970's.

I found a series of pictures I took when an early Space Shuttle visited Stansted Airport in Essex in June 1983, 30 years ago this coming month. This was the Enterprise which did not go into orbit, but was used for a series of captive and free flight tests.

Stansted then was a relatively small regional airport, considerably different to today.

Following two photographs give some idea of the visit.
 







Dreadful Weather and Receiving Weather Satellite Pictures

For almost the end of May, the weather has been dreadful today with temperatures staying around 6 degrees centigrade all day, lots of rain (10mm) and strong winds. The cause has been an area of low pressure tracking from the northeast to the southwest directly across the country.

For monitoring weather I receive weather satellite pictures transmitted by EUMETSAT via the EUMETCast system. With both static pictures and the ability to build an animation over time, the EUMETCast facility provides a fantastic way of watching what is going on, and seeing the cause of the weather we get on a day to day basis.

The following picture is from the early afternoon and shows the core of the low pressure area approaching the Wash, it continued tracking south west for the rest of the afternoon. very unusual pattern for this time of year.



© EUMETSAT (2013)

EUMETCast also distributes a 5 minute updated picture, these can be built up into an animation to show how the weather changes over a period of several hours. Perfect for watching the track of weather systems.

I will provide more details of my receiving system in a future post. For now, an excellent source of information is from the Group for Earth Observation http://www.geo-web.org.uk/ and full details of EUMETSAT services are at http://www.eumetsat.int/Home/index.htm

For decoding and displaying all the data received via EUMETCast I use the excellent software available from David Taylor at http://www.satsignal.eu/

On the Radio, worked one of the many special event stations operating at the moment. GS5NB was operating on 40m from the Ness Battery on the Orkney Islands. See http://www.qrz.com/db/GS5NB for details.

JT65 and will I ever make contact with Hawaii?

One of the data modes I use frequently on HF and have done for about 18 months is JT65. The software I use is the excellent JT65-HF by W6CQZ which is based on the JT65 protocol, the creation of K1JT.

It is amazing the distances that can be worked with low power and a small wire aerial.

It is also good for understanding propagation by using sites such as http://pskreporter.info which displays which stations are receiving your signal.

The following picture is a snapshot of PSKReporter earlier this evening showing where my 20m JT65 signal was being received:

For data modes such as JT65 I use my Kenwood TS2000 feeding into an off centre fed dipole fed by a 4:1 balun and tuned using the internal ATU within the TS2000.

I have worked most US states using JT65 including Alaska which I have not been able to do via any other mode in over 10 years on HF. The key one that is missing is Hawaii. Even when I have seen stations monitoring and reporting on PSKReporter, they have not seen my signal. Hopefully it will be a matter of time and getting propagation right.

So if any radio amateurs from Hawaii read this, I would really appreciate a contact !!

Finally decided to start a blog. Not that the Internet needs yet another Amateur Radio blog, rather it is a means for me to record my activity and hopefully it will be of some interest to others.

Main interest is Amateur Radio, having been licensed originally in 1976 as G8LMY. Now hold the call sign M5LMY. Prior to getting the licence I was a Short Wave listener starting with the commercial bands before finding amateur radio transmissions.

Photography is another interest and the photo in the header is a panorama of one of my favourite places, Portsmouth Harbour. Made from a number of individual photos, stitched together using Panorama Plus from Serif.

Not much activity on the radio today, small bit of JT65 on 20m and worked GW100RSGB on 40m this evening.  This being one of the RSGB centenary stations.