Galway City Multimode Digital Gateway EI2GCD

On Monday the 13th of November 2017, the Galway City Multi mode Digital Gateway was pressed into service. The Digital Gateway is fabricated from a Motorola GM350, Raspberry Pi, Arduino Due and a MMDVM modem board. See Picture below.

With assistance from John MI0AAZ on Team Viewer, the program was initially set up on the Raspberry Pi. Unfortunately, the setting of the Transmit and Receive audio levels were critical and required setting on a spectrum analyser. John McCarthy EI8JA had performed this task on his own Repeater and offered to set these critical levels for us. The Repeater was returned and a decision was taken to load the Pi-Star software on the Raspberry Pi as it was easier to manage and set up. 

At the same time Joe, EI3IX, had built a similar system for the Mayo area. It was decided that we would adopt the same Software for his Gateway. The aim was to place the two systems on air together.

Once Pi-Star was installed on both systems it was possible to mimic the settings and they both worked with a few minor problems that were easy enough to rectify.  A Skype chat between Mayo, Galway and Northern Ireland enabled final checks and the Gateways were powered within minutes of each other.

The GM350 and the Raspberry Pi booted up together with the status lights indicating that all was well.

Following tests on both Yaesu Fusion and DMR, the system appeared to be connecting to the server and stations were being heard by the system. A typical screen shot from the Pi-Star dashboard is shown below.

The dashboard was well populated in a very short space of time with DMR contacts. Yaesu Fusion was tested later and proved to be functioning well. The Brandmeister Dashboard revealed the connection was functioning properly on both DMR and Fusion.

A look at the network map showed the Gateway positioned in its corrrect location in Galway City.

The map coordinates were interpreted properly on this occasion unlike my DV Mega which was shown about a mile further east from my home location. 

Whilst there is not a huge amount to activity in Galway, this system will, at least, bring some activity to those who do go on the air and also provide an opportunity to operate whilst mobile in the car or walking with a handheld radio.

For further information about this project see the EI5DD Blog >>  click here
Further information about Digital Radio may also be found on the EI5DD Blog.

Special thanks to John Anderson MI0AAZ, John McCarthy EI8JA, and Joe EI3IX who were all involved in the set up and final testing phase of this Gateway.

Parameters and operation: Click>>>  HERE
 

Specifications of the Galway City Gateway

Call sign EI2GCD

Location Galway City

Frequency 144.8500 MHz

Time slot 2 

Colour code 1

Default DMR Talk Group TG 2722 ( Ireland Calling) 

Default Yaesu Fusion Server IE YSF Ireland

Sysop Steve EI5DD - reports welcomed >> HERE

---oo00O00oo---

Specifications of the Mayo Gateway 

Call sign EI2DOD

Location 10m East of Castlebar Co. Mayo

Frequency 144.8250 MHz

Time Slot 2

Colour Code 1

Default DMR Talk Group TG 2722 (Ireland Calling)

Default Yaesu Fusion Server IE YSF Ireland 

Sysop Joe EI3IX - reports welcomed>> HERE

Read More

Galway City DMR Repeater EI7RHD

A proposal has been made to set up a DMR repeater for the Galway area operating from a site near Circular road on the West side of the City. Our group was offered a reasonably priced Hytera 985 repeater which was really not to be refused. 

This Repeater is a Commercial system easily programmed to operate on the 70cms band. Once connected into the internet, it will network with the Brandmeister Server located in Waterford giving connectivity o a worldwide basis . The Hytera is capable of running 50 watts but we will reduce this to 30 watts as there is little point in running it to the extremes of its capabilities. 

The cavity filters are situated on the chassis. and, unlike an analog repeater, these cavities will operate quite comfortably at 30 watts without warming. As the DMR signal is 50% duty cycle, these will run and remain cool and stable. There is a facility to run an Analog signal from this repeater but this may be a conflict of interest. There is already a 70cm Analog Repeater in the City and also EI7AKR situated in a rural area to the East.

The proposed coverage from site chosen is as follows:

The antenna will be a vertical system which is a 3 x 5/8 colinear antenna giving a reasonable gain over a dipole. This plot was derived assuming 30 watts power and the antenna with a gain of 9dB. over a dipole. 

This will be the third DMR repeater to be established in Ireland and will be networked into the existing Brandmeister system. 

This Repeater will facilitate those with an interest in DMR and the development of this aspect of the hobby. The networking capabilities are endless and will ensure that any activity in Ireland will be transmitted to our area. 

To see more of the digital facilities around Ireland click here
EI7RHD Web page click >> Here

Read More

Digital Radio

DMR Radio

With the availability of cheap handheld transceivers manufactured by the Chinese, DMR Radio has become popular amongst the amateur radio fraternity. There are a number of handhelds to chose from, ranging from Tytera, and clones such as Retevis, and Zastone.

The Zastone became a big hit when it was offered as a pack of two handheld transceivers for £108.00. This was a UHF handheld which could be easily programmed with Tytera Code Plug software. It was in fact a clone of the MD-380. The pack contained two chargers, a programming lead and a "Matrix" style earpiece/microphone. In a short period of time, the sale was over as the stock diminished overnight. At the time the Tytera was selling for £80 - £90 on other outlets such as Amazon. Most were UHF but VHF transceivers were also available but not as popular.

A new kid on the block is the Radioddity GD-77 which is a dual band VHF/UHF handheld transceiver.

Things have moved forward to the point where the Radioddity GD-77 was released at 66 Euro. There was a sale announced and the stock was sold out within 3 days. Even at a higher price of 80 Euro on Amazon, the stocks were cleared overnight.

This radio is well supported by the manufacturers via a Facebook Page. Feedback from customers and their wish lists were taken into account and appropriate Firmware upgrades follow. Not only are all of these DMR radios capable of operating in Digital Mode, but, they can also be programmed for Analogue channels. At current prices, they can easily compete with Wouxun and Baofeng handhelds.

For some time there were no mobile DMR transceivers apart from the expensive Motorola versions which sell for £365 upwards. Either VHF or UHF versions can be purchased with or without the Keypad microphone which retails for £85.00. Pictured below is a Motorola DM4600. 

These DMR sets are for Commercial use and have many additional features not normally used by radio amateurs. They are not easy to program but one has the ability to program a more basic set, it follows the same pattern. 

It was not too long before a dual-band mobile radio was marketed by TyTera in the form of the MD-9600. This operates on VHF and UHF and it is possible to program both VHF and UHF channels into this radio. It has great prospects and will be backed by regular updates by the manufacturer.

This Transceiver is almost as easy to program as the Tytera range of handhelds.

There is a little effort required to program a DMR radio but once one has the grasp of programming a code plug, life does become easier.

Link to Basic DMR Programming Tutorial >> here

A Brandmeister network has been established in Ireland and has three Talk Groups:

1) Ireland Call Channel - Talk Group 2722 -  needs to be programmed as a channel in the code plug

2) Ireland Chat Channel - Talk Group 2723 -                 -- As above --

3) YSF Ireland Channel  - Talk Group 2724                   -- As above --

The YSF Ireland Talk Group bridges DMR to Yaesu Fusion (re-transmits the audio from DMR onto Yaesu Fusion and vice versa. If one is operating DMR on this Bridge they may have QSOs with Fusion operators and vice versa.

Yaesu Fusion (C4FM)

Yaesu Fusion is probably the easiest way to get on air with a Digital Mode. The Transceiver may be taken straight out of the box an, after programming the call sign without having to read the manual. It is, however, necessary to read the manual to derive the benefits of the fusion mode. Some examples of Yaesu Fusion equipment are sown below

Yaesu has developed the Digital Wires-X Network accessible by pressing the DX button on the front of the transceiver. This is, essentially, a more up to date version of Echolink or IRLP with a superior network capability. With Wires-X, it is possible to press a button on the front of the rig to access the network and choose a room from a chosen part of the world to make a call.

The Galway VHF Group has recently given a contribution to the Galway Radio Club towards a new Yaesu Fusion Repeater which will be fitted with the Wires-X system. This should go on the air in October 2017.

The Multi-mode Digital Gateway situated on 145.850 MHz, covering DMR Fusion and D-Star, will cover Galway City and a surrounding radius of 25 miles. This will go on air in October. The Call sign will be EI2GCD.

A Yaesu Fusion Gateway, with similar coverage, will be going on air in October. The Callsign will be EI2SHD and the frequency will be 144.8125 MHz.

All of the Galway VHF Group are currently active on Yaesu Fusion and some are active on DMR. The Galway VHF Group would be delighted to assist anyone who wishes to enter into the field of Digital Communications.

If you wish to discover more about this aspect of the Hobby contact Steve EI5DD at wrights1@eircom.net

More information may be obtained >> here

Considerations for a Digital Radio System in Galway may be obtained >> here 

Read More

Installing the 70cms Repeater at Knockroe

A meeting prior to the installation ensured that all parts had been purchased and also who currently had them in their possession. The last item required was the 20ft pole. John looked after the purchase and delivery of the pole to the site.

Gerry took charge of the guying equipment and all of the necessary parts were handed to him. Andrew took charge of the fencing materials and the parts for the fourth guy which needed to be set in the ground on the day.

Steve held the repeater, sundry items and spares should they be required.

The group met in Abbeyknockmoy and headed for the site. Marlow joined us and oversaw the operation on his site.

The first task was to work on the brackets to hold the pole against the wall of the hut. Gerry took charge of this with the assistance of Arek.  

The next task was to organise the staying point for the fourth guy. Joe and Andrew looked after this duty. A fair bit of digging was involved until a huge lump of rock was found. 

This rock was going nowhere so the best course of action was to drill into the rock and insert a rawl bolt. This has a couple of small clamps added and the fourth guy was affixed to this. Concrete and rocks were poured over this and then the rest of the earth covered it. A small fence was built around this area to prevent cattle damaging the guy and staying point.

The pole was raised to ascertain the length of the steel guys and also the fourth guy which would have been longer. Once this was done it was time to bolt the antennas to the pole. 

The raising of the mast was not too difficult with a little muscle and weight behind the mast

Gerry spent much of the time on the roof of the hut ensuring that the guys were secure. The tensioners did not need adjustment so there will be plenty of play to tighten them in the event of the guys stretching.

And so the last of the guys were attached and secured to the Rawl Bolt on the rock. With all in place it was time to look upward and see the results of the work done.

And then into the hut where John had been working on the installation of the Repeater and the APRS Digipeater.

A great day was enjoyed by all. The installation took four hours to complete. A great days work was done by all with special thanks to the Team - John EI1EM. Tom EI2GP, Joe EI3IX, Steve EI5DD, Andrew EI3FEB, Gerry EI8DRB, and Arek EI9GWB and not forgetting Martin List-Petersen who oversaw the operation and took the photographs shown here.

Read More

Galway 70cm Repeater - EI7AKR

The Galway VHF Group 70 cms Repeater is now 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 Radio-Mobile show a pretty uniform coverage of the County of Galway in almost all directions. 

As can be seen below, the coverage is impressive. This will facilitate many operators who just can not experiment with communication over distance using UHF Radio. The primary objective is to give saturation coverage of the County and, more importantly, the main routes into and out of Galway City. Regrettably, this is not possible in the direction of Clifden due to the proximity of the 12 Pins and Maamturks, however, coverage into Oughterard, and just beyond, is possible. Whilst predicted coverage is impressive, the actual mobile coverage may bring in even more surprises.

The Individual components of the Repeater are as follows

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 feeder will be used. The repeater was supplied by WESCOM and modified by Enda O'Brien EI5GMB.

To achieve the isolation between transmit and receive it is necessary to insert a bandpass/band-reject filter in line. This is one area where compromise is not an option. A set of six Sinclair cavity filters were purchased. Expensive but perfect for the job. Careful tuning using a spectrum analyser and/or a VNA was required to achieve the best possible rejection. The specification suggested that there would be 120dB of isolation between the receive and transmit frequency and we were using a 7.6MHz split.

Ideally, the cavity filter needs to be tuned into the feeder and antenna in use on-site. Although the cavity filter can be tuned into a 50 Ohm load, it will be necessary to tweak it up on site. If one changes the antenna or feeder the whole process of tuning the cavity filters has to be repeated as minor changes to the load will alter the characteristic curves. Shown below are the characteristic curves on the receiver tuned to 432.825MHz. 

We were fortunate that we were able to tune the cavity filters into the correct heliax feeder and antenna system prior to installation on the permanent site. This will reduce the amount of time spent tuning on site. It will probably be necessary to make minor adjustments before leaving the repeater once the installation has been completed.

It is now possible to run 30 watts of power without any worry about desense or drift. With the present power setting, it has been possible to get into the repeater with an S 1 signal received from it whilst it is transmitting 30 watts. This may have to be balanced on-site but at this stage, it may not be necessary. 

There is no noticeable temperature effect causing the cavity to pass or reject bands to drift. We had tried the small Procom type filters which actually heated up when our transmit signal was passed through them. This resulted in the characteristic curves to drift and resulted in desense after a couple of minutes of use. A search on the internet revealed the Sinclair cavity filters. These were by no means cheap but it is far better not to compromise the system for the sake of saving a few Euro. 

An RC-100 Repeater controller deals with the identification and timings of the repeater. The repeater is accessed using a CTCSS tone of 77 Hz as it is considered irresponsible to allow spurious triggering from a carrier operated squelch. Through this controller, the Repeater can be switched off at short notice if required to do so. 

The Antenna is the most important part of the set up.

The antenna system was obtained from Radio Structures Ltd in the UK. It was designed specifically for the task taking into account the Transmit and Receive frequencies. the Gain of the antenna is 5.5dB gain over a 1/2 wave dipole. The antenna is true Omni-directional and the characteristics are shown below. 

There is little point in producing a professional system without a professional antenna fed with low loss coax. In our case, we used Andrews heliax with negligable losses at UHF.

Status - Active

Call sign EI7AKR

Repeater Access by 77 Hz CTCSS Tone

Modulation Narrow FM (+/- 2.5 KHz)

The IRLP Node Number is 5705

The Echolink Node Number  5705

Echolink Node EI7AKR-R

Locator Reference for site IO53PK

 

Output Frequency 430.825 MHz  

Input Frequency 438.425MHz

 Frequency Shift + 7.6 MHz 

Please note Time-out 2.45minutes

Repeater Keeper - Steve Wright EI5DD

Reports to wrights1@eircom.net

Read More

Experiments with C4FM

We now have six stations in Galway operational on Yaesu Fusion. Steve EI5DD, Tom EI2GP, John EI1EM, Arthur EI7GMB, and Gerry EI8DRB,  have FTM400XDR transceivers and Andrew EI3FEB has an FTM100. Dermot EI7IX from Westport recently purchased an FT100, whilst Joe EI3IX, and John EI7FAB, from Castlebar Co Mayo, should be on shortly so the efforts have finally borne fruit. Arthur EI7GMB will have an FTM100 in Galway shortly. Gerry EI8DRB owns a Yaesu FT991 which incorporates C4FM. Nine on the air in a short time is impressive.

The Limerick area, due South of Galway,  have a Yaesu Fusion Repeater which provides a good signal throughout Galway and into Co. Mayo as far west as Westport. The current number of Fusion operators in the Limerick area would appear to be around ten or eleven.

Plans are to place a Wires-X gateway online by the end of April, which will serve Galway City and the surrounding area of 25 Km radius.

The first experiment was carried out between EI3FEB in Headford and me in Galway City - a path of 23.5 Km but it had a few hills in between the two stations so was a poor path at the best of times. The path was chosen as this was probably the worst signal strength achievable.

Both rigs were set up to transmit 5 watts and the initial transmission was made on FM

As can be seen on the display the signal strength did not even register and the FM signal had the usual hiss encountered with FM signals received on the fringe area. For an S0 signal, it was not to bad. The FTM 400 recorded the returned signal as S 0.5 - S 1. Readable with plenty of hiss. Note the FM displayed to the right of the frequency displayed indicating this was in the FM mode. The lower green light indicates FM reception.

The mode was changed to C4FM and the signal received was most impressive

This signal was still received at an S zero level but his time in C4FM. The quality of audio was crystal clear with absolutely no background noise. Note the DN displayed to the right of the frequency displayed denoting in digital mode. The blue light denotes the reception of a digital signal. When the digital signal is received other information is embedded within it which includes the Call sign and also GPS coordinates. The distance as shown was derived from that information.

Check out the YouTube video  https://www.youtube.com/watch?v=I90774lrNvU

Quite impressive with no R2D2 sounds from the received signal.

More to follow   .......................... 
Original work from the EI5DD/G4GFC pages Click here

Read More