Wednesday, August 27, 2014

M0XER Balloon Flight Logged by EI2GCP

At 11:00 utc 22.08.14 the MoXER-4 Balloon was logged, by EI2GCP APRS Digi, flying towards the North West coast of Ireland. The Balloon's Altitude was 12,262 metres and speed 88km/h. Tracking continued until 14:14 UTC where the balloon was then picked up by EI2LLP as it passed over Westport. EI2LLP is located just South West of Dundalk. Numerous reports had been received around Ireland by individuals with APRS equipment in vehicles and at home.

Passage of M0XER-4 from 22/08/2014 - 27/08/2014

The M0XER-4 Balloon is a homemade plastic envelope carrying an Amateur Radio payload launched from the UK by Leo Bodnar, M0XER. The balloon carries a tiny 10mW Solar Powered transmitter weighing just 11gm. If the APRS transmitter falls out of range of a Digipeater, it can store up to 5 days of positions in its APRS Comments field. If, however, it has been out of radio contact, a straight line will appear on the APRS map

Lecture Covering Scatter Propagation on 23 cms by Anreas DJ5AR

On Monday the 25th of August, Andreas DJ5AR gave a comprehensive lecture on the subject of Aircraft Scatter Propagation on 23cms.  Members of the Galway VHF Group, The Mayo VHF Group and M.R.E.N. were present.

Often references are made to Rain scatter which is prevalent on 10GHz and to a lesser extent on 23cms where the scatter is only possible from Storm or Thunder Clouds.

A typical Storm Scatter path on 23cms - note that the that the Direct path was inaudible
Initially it was observed that, during flat conditions, a beacon signal would come out of the noise to reasonable signal  strengths and drop back into the noise again after a couple of minutes. Subsequent research revealed that this scatter was probably due to scatter from a reflection from an aircraft flying across or along a specific path between two points in this case between the beacon and the monitoring station.

The hypothesis used is that a microwave signal is reflected by the airplane body and wings according to the famous formula “angle of incidence is equal of angle of reflection”. As the airplane's form is not flat, but curved, there is always some part of the airplane that produce a usable point to bounce off for any two radio stations as long as both radio stations has LOS (line of sight) to the airplane, i.e. the airplane is above the radio horizon. The magnitude of the reflected signal is proportional to the size of the reflecting area – in this case broadside to the plane as opposed to the profile from front to tail.

The signal will increase as the plane approaches the path between the two stations and then diminish after it has crossed that path. The larger the airplane the better reflection, read signal strength, there will be. Another interesting effect is that the signal strength is not frequency dependent, given that all other factors are the same, e.g. ERP , RX NF, etc.  The difference will in a typical case be the time duration of a reflection, as the higher frequency usually has a much higher gain antenna, narrowing the volume of airspace available for the airplane (assuming that the antennas are static, not tracking the airplane). One does have to be lined up for the path at least 7 minutes before the plane is due to cross.

When an airplane is traveling exactly along the bore sight between two stations, and the airplane is in the central part of the path, there will be no Doppler. But as soon as the airplane deviates from the bore sight, there will be some Doppler. At longer distances, e.g. 100 km or more, the Doppler will be small, assumed that the airplane travel in the general direction from one station to the other. If however an airplane is crossing the LOS at an angle that is perpendicular to bore sight the Doppler from that airplane is very audible, going from a higher frequency as the airplane approaches the bore sight. 

When crossing the bore sight the transmitted frequency will be equal to the Doppler. When moving away from the bore sight, the Doppler will be lower in frequency - behavior much as we would expect. When passing perpendicular, the Doppler will shift rapidly, when passing at an obtuse angle, the shift will be of longer duration. The Doppler frequency is typically of +/- 200-300 HZ on 3cm and each station using 60cm dishes, equivalent of a theoretical antenna gain of approximately 33dB. At times, several Doppler signals may be heard due to multiple airplane reflections.

 Screenshot of "AirScout" Showing the transmission Path and Aircraft in the vicinity

A screenshot of "AirScout" illustrated the communication path. Aircraft that may be suitable reflectors are coloured in purple. At the bottom of the frame is an graph of terraine and just above that is a graph showing the probable area for the reception of reflections.

It has been estimated that the very best distance achievable, using aircraft scatter, is 450Km. The antenna would need to be a high gain antenna and ideally a 3 metre dish although a high gain Yagi antenna will suffice. Ideally a power of 200 watts is the goal to aim for, but this mode of propagation is still possible with lower powers and Yagi antennas. With this kind of set up at the receiving end weaker signals will be picked up. Bear in mind that some beacons only radiate 4 watts and it has been possible to receive them at a distance of 400 Km. It should be noted that the radio horizon is greater than the optical horizon and does increase with frequency.

Of course one does not have to stop at aircraft, as it is possible to bounce a signal off a moving object in space if it has a large enough profile. The ISS would be on example along with many other items flying around the earth. One does have to take into account the increase in Doppler Shift of such bodies as they are passing across the horizon at considerably higher speeds.

In conclusion, one does not have to be on an elevated site to avail of Aircraft Scatter Propagation, although it does help. It is possible to scatter off other flying objects such as space vehicles, Satellites, the Moon and other planets; an example being the signal returned from the planet Venus. Many slow fades experienced on VHF maybe attributable to Aircraft Scatter and not necessarily due to tropospheric anomalies.
 L-R Steve EI5DD, Dermot EI7IX, John EI7FAB, Brendan EI6IZ, Andreas DJ5AR and John EI1EM

Saturday, August 16, 2014

M.R.E.N. Blacksod Lighthouse Operation EI0M/P

Clubs and individuals all around the world set up their Amateur Radio Stations in lighthouses and participate in the International Lighthouse weekend activity. This is not a contest operation but an operation that enables many avid collectors of Light House numbers to achieve I.L.L.W. and B.A.R.L.S awards. This event was gaining interest as early as June where the numbers of stations registering were topping previous years.

One Group who participate in this event are the Mayo Radio Experimenters Network. They take the operation seriously and operate from a caravan parked next to Blacksod Lighhouse located beyond Belmullet. This year they were using two Icom IC-7200s and also an Elecraft KX3 running into an Elecraft 100watt Linear. There were dipoles for 80 and 40 metres, A 5BTV vertical antenna and a Spiderbeam. The Spiderbeam was to be supported on a trailer Tower.

Those participating were Dominic EI9JS, Jimmy EI2GCP, Padraig EI9JA, Brendan EI6IZ and Steve EI5DD. Modes of operation included SSB, CW and PSK. Unfortunately I (EI5DD) could only stay for a short time due to an AREN event taking place on Sunday morning. Weather conditions were mild but prone to light rain which did not impede the setting up of the antennas. Band conditions during the afternoon were poor on 40 metres with some very strong stations but a lot of QSB. Hopefully all would change later in the evening. A few pictures of the initial set-up are included in this section.

Brendan EI6IZ

 Dominic EI9JS

Thursday, August 14, 2014

IRTS Weekend in the Galway Bay Hotel 2014

Probably our most enjoyable activity this year was the hosting of the IRTS Annual Dinner, the Galway VHF Group Rally and the IRTS AGM. The first time we ran the IRTS weekend in the Warwick Hotel, Galway was in 1986, the second time was in the Royal Hoey Hotel in Athlone in 1992, and this year on the 22nd and 23rd of March.

The dinner was attended by 68 people, and the food was just perfect. There were no complaints about the food or service. The accommodation was excellent and the rooms for the Rally and the AGM were more than adequate to accommodate the numbers attending. The Hotel provided excellent service and the bottom line was that nobody could find any fault with the services or organisation of the weekend.

The Rally saw all the major traders with an appearance from Mike, EI0CL, who had a huge selection of equipment both new and second hand.
Maplin Electronics were first time attendees of this event and produced an excellent display of their products. There was no white space in the venue as very table had been occupied even to the point where we had to squeeze a extra few tables into the corners of the function room. There was adequate space to walk around displays and no excuse for any occupant of a wheelchair to bump into or run over people despite the large numbers attending. We even had the Freemasons occupying a stand where they sold Teddies for the Charity “Teddies for Loving Care”. The Teddies Charity supply Teddy Bears to young children admitted to the A&E departments in many Hospitals around Ireland. Our special thanks go to members of the Mayo Club who organised thier bring and buy stand which became the meeting and focal point of the Rally.

Here are a few Pictures of the Event 

Basil Fenton with the Freemasons  "Teddies for Loving Care" Stand
 Maplin Electronics
Long Communications
Gerry EI8DRB
Eddie EI3FFB
Garry - South East Communications

Plenty of equipment exchanged hands or was sold at this event. We had 167 through the door which is a sign of recessional times and hopefully numbers will climb in future years. There is no doubt that Amateur Radio is still a thriving hobby but there is a noticeable reduction of younger people showing an interest in radio and communications.

We thank all the Traders who attended the Rally, and all those who attended the weekend and supported this event and, of course we thank the Staff of the Galway Bay Hotel for their services which contributed to the smooth running of the event.

The proceeds of this event went towards the 70cm Repeater, the 4m Gateway, and upgrading the APRS Network.

Summer 80 metres Counties Contest 22nd June 2014

The 80 metres counties contest, held on the 22nd of June, provided an excellent opportunity to experiment with some 80 metre antennas. Steve EI5DD and Enda EI3IS set out around 11:30am with the intention of building antennas.On this occasion, a full 80 metre loop was constructed which used 283 ft of wire kept to a square shape and mounted approximately 6ft off the ground on bamboo canes. The idea behind this was to produce a good NVIS signal to cover the country. 

Being summer, and considering D-Layer absorption, this really wasn't going to happen around mid day. The antenna was tested on all bands as this particular antenna works on all bands from 80 - 10 metres. Obvioulsy, if it is raised much higher off the ground, it will be a good general purpose and low noise antenna. 

The Inverted-Vee was pressed into service and provided better results. This particular antenna was made up as a dual band 80 and 40 metre antenna with wire links to extend each leg from 40 metres to 80 metres. The antenna has provided good results on our AREN operations and other portable activities in the past.
The antenna was mounted on our last remaining 10m fibreglass pole. It performed well on this occasion. All areas of the country were heard and indeed later worked. Unfortunately, there were not a lot of Irish stations to be heard on this occasion.

The EI5DD portable station was pressed into service. The Tranceiver is an ICOM- 7200 and the tuner used on this occasion was the KW EZEE Match as we were using balanced feeder. MFJ tuners are not great with balanced feeder unless the specialy manufactured model is used - this is expensive.

At one time the hills between Spiddal and Galway were virgin and unspoilt territory, but the Wind Farms are systematically devastating the areas leaving little room for amateur Radio. Not a great proposition if attempting to fly a kite antenna! Before long the road from Spiddal to Moycullen will be covered with these atrocities running the skyline. One only has to look towards the hills between Gort and Loughrea to see the damage done. This will be the problem encountered on all high spots around the country with the exception of Wicklow where there is a very bitter campaign to keep windmills  from damaging the view.

The Counties contest ran for 3 hours and only 18 counties were worked so a log was submitted for the craic but would not see much coming out of our entry. Our Loop antenna will be hoisted for the winter counties contest and perhaps on a portable operation in the future.

Wednesday, August 13, 2014

Galway VHF Group APRS Network EI2GCP & EI2AKP

The APRS system is to be completely overhauled. The introduction of an I-Gate at the Galway City site in Mervue will feed data directly into the International APRS network enabling tracks to be viewed live on A weather station feeding live information into the network will also be installed at Mervue.

A second APRS digipeater will be installed at the Knockroe site at Abbeyknockmoy, Co. Galway. Coverage will be almost as good as that seen for the 70cm Repeater. This will provide seamless coverage and handover to digi-peaters covering the midlands  and possibly further south - something that would not be possible unless the higher site were to be employed.

Any data received by the Knockroe digi-peater will be retransmitted, picked up by the Mervue digi-peater and fed into the International network via the I-gate. This upgrade was long overdue and it will open many possibilities for the Galway VHF Group AREN operations both in Galway City and County Galway.

Frequency 144.800 

Callsign EI2GCP
Location Mervue

Callsign EI2AKP
Location Knockroe, Abbeyknockmoy

More information to follow on this topic .........

New Road Traffic Laws and Implications to Mobile Radio Operation

Whilst the new Road Traffic laws have stated that operation of Mobile phones whilst driving is illegal and perpetrators of such an action will be dealt  heavy penalties, it is possible to use Bluetooth Hands-free systems in cars in order to work within the law. Of course, dialing a number or texting is out of the question.The use of a microphone, whilst driving, does not fall into this category. If, however, one is stopped, there is the distinct possibility that "driving without due care and attention" maybe an alternative charge. Hands-free systems are obviously worth looking into if one wishes to continue their hobby whilst mobile.

Hands-free systems such as a single earpiece with a boom microphone would be one method to overcome this problem. An alternative would be to install an electret mic to the sun visor above the driver's head. There is a significant disadvantage to this method as general car noise will compete with the voice. Another problem is the trailing wires from the headset and their ability to tangle in the Steering wheel.

A good alternative is a bluetooth adaptor wired to the Tranceiver. The use of a bluetooth headset with this system, will provide excellent results. The PTT switch can be fixed to the gear stick. Some headsets provide a facility to tap a button to latch the PTT on or off via Bluetooth. Unfortunately, commercial Bluetooth Adapters are expensive and rigs with Bluetooth options as an accessory are also expensive. It is possible to build a Bluetooth adaptor for any radio although prices do increase when all the individual components are purchased. 

A commercial Bluetooth Adaptor may be found at this address - Bluetooth Headsets can be expensive but those available for use with Play-stations or X-Boxes may be purchased for less than £20.

Check the "Bluetooth Adaptor" link in Downloads for a detailed description of a project used by Steve EI5DD

4 Metre ECHO/IRLP Gateway EI4GCG-L

The Galway VHF Group 4 metre Gateway will be located on a high spot in the Mervue area. The 4 metre Gateway is not intended to cover any more than Galway City and surrounding areas. We are happy enough if it just covers the townlands around Galway City such as Oranmore, Headford, Furbo, Moycullen, and Claregalway. Those with good antennae may access this Gateway from further afield.

The predicted coverage from RadioMobile map reveals just perfect coverage for our needs along with some addditional areas. City wide coverage and even coverage to Athenry, Kinvara and beyond Claregalway and further out from Moycullen has been confirmed by the use of the existing APRS coverage on 2 metres from this site.

The 4 metre Gateway is built using a Kyodo commercial Low band Tranceiver. A Raspberry Pi ECHO/IRLP controller is added and the radio is fed into a 4 metre dipole located on the roof of the building. Nothing stunning or startling about this system; it is very simple. Remote control is also included if necessary to switch the Gateway off at short notice.

This is not intended to be a "DX machine" but merely an asset to bring in activity from other EchoLink or IRLP Nodes around the country or abroad. Some VHF Group members are often working elsewhere so this will provide an excellent opportunity to keep in touch locally. There was never really a plan for this to be used from a mobile operation point of view, but it would be possible. One does have to consider that to key in DTMF tones is neitherr conducive to good driving practice nor within the framework of the new Road Traffic Acts.

The 4 metre Gateway will be located on 70.425 with CTCSS access using 77Hz tones. It is possible to chat away on channel without the tones switched on and the unit will not activate. If, however, somebody does access the Gateway, one can switch in the CTCSS tones and have a conversation with the operator concerned. Obviously it is better to monitor this channel without CTCSS tones switched in. This will enable local conversation on the same channel as well.

Callsign EI4GCG

The Echolink Node Number:  5422
The IRLP Node Number:       5422

EchoLink Node Call EI4GCG-L

                                                     Power  -       12 Watts
                                                     Antenna -     Dipole.
                                                     Location -   Mervue, Galway City
                                                     Locator -      IO53LG

Operating Frequency 70.425

Galway VHF Group 70cm Repeater - EI7AKR

The Galway VHF Group 70 cms Repeater is shortly to be located at its permanent home on Knockroe, Abbeknockmoy, Co. Galway. This is a prime site with a superb and unimpeded view in all directions. Initial predictions using RadioMobile show a pretty uniform coverage of the County of Galway in almost all directions.

As can be seen below the coverage is impressive and will certainly be an improvement on the coverage of the present 2 metre Repeater located on Tonabrucky just outside of Galway City. This will facilitate many operators who just cannot experiment with communication over distance on UHF Radio. The primary objective was to give saturation coverage of the County and, more importantly, along the main routes into and out of Galway City. Regrettably this is not possible in the direction of Clifden due to the 12 Pins and Maamturks, however, coverage into Oughterard, and just beyond, is possible. Whilst predicted coverage is impressive actual mobile operation may bring in even more surprises.

The Repeater is fabricated from a modified Commercial Kyodo UHF Repeater unit running 40 Watts fed into a 4 stacked dipole array with an actual gain of 6dB. Naturally ultra low loss coax feeeder will be used.

See below photographs of the individual components of the Repeater

In addition to the standard Repeater control circuitry, in this case a RC-100 controller, there will be a Raspberry Pi ECHO/IRLP controller. This system will considerably enhance the operation of the Repeater by bringing in activity from other countries and not forgetting other areas around Ireland. Remote control is fitted to switch off the Repeater at short notice or in the event of interference.

RC-100 Controller
RPi  ECHO/IRLP Controller

The 4 Stacked Dipole Array -  Pointless using anything less on UHF

Polar plots prove the perfect choice for this application


Callsign EI7AKR

Repeater Access by 77Hz CTCSS Tone
The IRLP Node Number is 5705
The Echolink Node Number  5705

Echolink Node EI7AKR-R

Locator Reference for site IO53PK

Input Frequency: 438.425   Output Frequency 430.825   Frequency Shift 7.6 MHz

Watch this space for more information as the project nears completion