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

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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

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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

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