Successful 5.6 GHz ATV test in Cork Harbour

As part of the ongoing Cork VHF Group nets on Tuesday evenings, we hold an experimental night whenever there is a fifth Tuesday in the month. On a previous evening, we experimented with sending and receiving Slow-Scan TV pictures on 2-metres FM using apps on Smartphones. For the fifth Tuesday of September 2020, the group experimented with Amateur TV signals at 5.6 GHz.

For the experiment, Jim, EI8GS went portable to the town of Cobh and set up his ATV gear to point at Don, EI8DJ in Crosshaven. After discovering that there was no reception through a glass patio window, Don took his gear outside and successfully received an ATV signal from Jim at 5.6 GHz. The distance of the path across Cork Harbour was 4.7 kms.

The photo above looks a bit crude but it's a screenshot from my PC from a Zoom meeting of a phone pointing at another screen! What it shows are the lights from the oil refinery at Whitegate in Cork Harbour and the small string of lights to the left is the village of Whitegate itself. The tests were done when it was dark so the picture would be more relevant and clearer if it was in daylight.

The lines in the foreground are in fact superimposed by the camera. The unit is supposed to be used as an aid for vehicles reversing and the lines show the 'safe' distance areas. In this case, it was used for sending an ATV signal across Cork Harbour!

The photo above shows what Jim, EI8GS was using in Cobh. He was located at a well known viewing point high above the town allowing a good line of sight path across to EI8DJ in Crosshaven.

Jim was using 0.6 watts output power into a 40cm dish with a dipole at the feed point. 

Next it was Jim's turn to try and receive an ATV signal from Don. The receiver module is shown above and a photo of the signal received by Jim in Cobh is shown below.

Don sent a number of different test cards and this is another screen shot...

The photo below shows the set-up as used by EI8DJ...

The grey box (top left) contained a Raspberry Pi Zero which generated the sequence of test cards. 

The module in the centre with the display is a portable screen that is used by drone pilots. It has its own 5.6 GHz receiver built in.

The top right box contains the 5.6 GHz transmitter module and the antenna mounted on the outside of the box is a 4 element Bi-Square with a reflective plate behind.

The photo above shows the box containing the transmitter module with a microwave relay on the left for switching from receive to transmit. The PCB in the background with the toroid is a voltage upconverter to generate 28 volts for the coil of the changeover relay.

The FM ATV signal from the transmitter has a measured output of 0.6 watts.

In conclusion... The purpose of this initial experiment was more of a proof of concept than anything else - i.e. could an ATV signal at 5.6 GHz be sent over a line of sight path and over a modest distance of about 5 kms. The answer was a conclusive yes!

The next steps the group are looking at is maybe to look at increasing the distance and exploring more paths.

About 20 years ago, there was a small but active group on 23cms (1.2 GHz) using ATV in the Cork area. Hopefully these new experiments might reignite some interest in the mode.

Local experiments on 23cms...

Every Tuesday evening, we have a local VHF net in Cork and a few of us get together for a chat. We use the the 6m, 4m, 2m and 70cms bands and which one we use depends on which Tuesday of the month it is.

It usually covers the first four Tuesdays of the month and if there happens to be a fifth Tuesday then we gave it a skip. A few weeks back, we thought it might be a good idea to use the fifth Tuesday in a month for experimentation, to try something that we don't usually do.

From this concept came the idea to try the 23cms band, i.e. 1296 MHz.

Denis, EI4KH near Watergrasshill has a Yaesu FT-2312 23cms transceiver running 4 watts on FM only and his antenna is a 26 element Yagi horizontally polarised.

A sked was organised with Don, EI8DJ who was located in a car at Camden near Crosshaven at the mouth of Cork harbour, a distance of 22 kms or 13.8 miles.

While the path wasn't line of sight, both Denis and Don were in good high locations. EI4KH was about 120m above sea level while EI8DJ was at a spot about 45m above sea level.

As the plot shows below, any obstructions on the path were several kms distant which made them less of an obstruction.

For EI8DJ's portable set-up, he was using a scanner for receive with a home made Bi-Square antenna shown below which was sitting on the dash of his car.

Using a frequency of 1290.000 MHz, EI8DJ managed to hear the FM signal from EI4KH at an estimated S'4' signal strength and a successful 23cms to 2m crossband contact was completed.

EI8DJ found the Bi-Square to be suprisingly directive and later peaked the FM signal from EI4KH to a maximum of an estimated S'7' signal strength.

The experiment was repeated with EI8DJ back in his driveway which is some bit lower than his portable location. From his home location, EI8DJ couldn't hear any sign of the FM signal from EI4KH.

While the distanced achieved were nothing special, it was interesting to see some local activity on the lowest of the amateur microwave bands.

Notes:
1) The beam heading for Denis was 170 deg.

Big opening from Ireland to Denmark on 40 MHz - Wed 19th June 2019

Sporadic-E conditions were really good on Wednesday the 19th of June 2019 with some very strong signals on 28 MHz. Propagation extended up into the VHF bands as well with the OZ7IGY beacon in Denmark being heard in Ireland on 28 MHz, 40 MHz and 50 MHz.

The beacon on 40.071 MHz was audible in Ireland for several hours during the morning and was very strong at times.

40 MHz Crossband Contacts... Lloyd EI7HBB in the west of Ireland made the best of conditions to make a 8m/6m crossband SSB contact with SM6BCD in Sweden. This is probably a first EI/SM crossband  contact for 8 metres.

EI7HBB was running 4 watts on 40.250 MHz from one of the Ukrainian transverters into a home made 2 element Moxon in the loft space of his house. He was listening to the Swedish station using a 4 element Moxon on 50.150 MHz.

The distance was 1343 kms.

2019-06-19 10:30:39 EI7HBB (IO53SQ) 40.250 SM6BCD (JO57WQ) 1343 IO53SQ JO57WQ cross band 50150

OZ7IGY Beacon... The OZ7IGY beacon on 40.071 MHz was logged by both Don EI8DJ and myself.

EI8DJ was using a Yaesu FT817 with a ground mounted HF vertical antenna to receive the beacon.

I found that I was getting some really strong signals with my 28 MHz vertical half-wave. I also found out by accident that I could actually hear it with a 2m Slim Jim!

It's probably fair to say that any sort of wire antenna would have heard the signal as long as the local interference was low.

Both EI8DJ and myself used the PI4 software to decode the beacon and to upload the spots to the cluster with Don doing it on three bands.

New experimental digital gateway for Cork Harbour...

In order to facilitate testing of digital modes, Don EI8DJ has set up an experimental low power gateway at his home in Crosshaven in Cork Harbour. Please note that this will be on air only when Don is in the shack so it won't be on 24/7.

Some of the specs are as follows...

Frequency : Simplex on 438.700 MHz

Modes : DMR, DSTAR, Yaesu System Fusion and P25

DMR Settings : Colour Code 1, Time Slot 2.

Power : 5w into a Diamond X50 colinear.

Coverage is dependent on terrain but tests suggest that it is pretty good out to about 10kms and perhaps further to stations out to 20kms on higher ground. Radio coverage software suggests that it may be accessible from high ground on the north side of Cork City but the south side might be out of range.

As can be seen from the map, it is in an ideal location for radio amateurs on visiting cruise and passanger ships stopping off at Cobh and Ringaskiddy.

Click to see large version of Cork City north side coverage

If you have any questions about the gateway, Don can usually be found on the Cork repeater or on the Southern Ireland Repeater Network.

Traffic and signal levels heard on the EI8DJ gateway can be seen HERE

For more information on digital radio locally, have a look at the digital page on the Southern Ireland Repeater Network website.