Sunday, March 19, 2017

Experiments with C4FM

We now have four stations in Galway operational on Yaesu Fusion. Steve EI5DD, Tom EI2GP and John EI1EM have FTM400XDR transceivers and Andrew EI3FEB has a 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 ownes 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 myself 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 too band. 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 a S 0 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 Callsign 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