Goonhilly to the moon and back - VHF · •DATV at 250ks would be 100 times weaker than SSB (2.5kHz BW) or 1000 weaker than CW (250Hz BW) •But the major issue is phase distortion

Goonhilly

to the moon and back (GB6GHY)

Neil Underwood – G4LDR

(G4NNS G4LOH G8GTZ)

Goonhilly

to the moon and back (GB6GHY)

Neil Underwood – G4LDR

(G4NNS G4LOH G8GTZ)

Introduction

• Goonhilly – it’s history

• How we got access to Goonhilly

• The equipment

• Digital Amateur TV Tests

• Two days of EME on 9 and 6cm

• Dish Performance Tests

• The future for EME operation from Goonhilly

History of Goonhilly • The site at Goonhilly Down is on the Lizard Peninsular in south west

England

• Chosen to give maximum mutual US/UK visibility for first generation low earth orbit satellites (Telstar) which was about 20 minutes

First Antenna at Goonhilly – GHY1

• First antenna was 26m dish ‘Arthur’ built 1962 • Dish was large to receive low power

satellites

• Had to be steerable to follow fast moving low earth orbit satellites

• Up-link on 6GHz, down-link on 4GHz

• First trans-Atlantic TV via ‘Telestar 1’ • French ground station at Pleumeur-

Bodou was first to successfully receive test transmissions

Goonhilly mid-sixties to present • Geostationary satellites replace low earth orbit satellites – fixed dishes

• Satellites have greater power available and higher output power and receivers became more sensitive – smaller dishes required

• Goonhilly became largest ‘teleport’ in the world with 64 dishes

• But gradually fibre optic cable took over most international communications traffic • Potentially unlimited bandwidth (just lay more cables)

A New Life for Goonhilly

• From 2006 British Telecom slowly moved satellite operations away from Goonhilly and the site was ‘mothballed’ in 2010.

• The site was eventually sold to the current owners Goonhilly Earth Station Limited (GES) in 2014 • GES Ltd. are a group of satellite engineers backed by investors

• Building site back up – repairing 10 years of neglect – All dishes except the big 3 are in traffic

– Installing new dishes

Initial Amateur Radio Access to Goonhilly

• GES Ltd. were keen to support Science Technology Engineering Mathematics (STEM) outreach programme during Tim Peake’s mission – Offered loan of 3.8m LEO dish to receive HAMTV from the ISS on 2395MH

Can we have a play with a big dish please?

• Noel G8GTZ (British Amateur Television Club (BATC)) asked if it would be possible to try Digital ATV moon bounce using one of the big dishes

• Three large dishes not in traffic • GHY1 – Arthur, built 1962, 26m diameter, had recently moved, grade 2 listed

• GHY3 – built 1970, not in use, needs considerable investment, grade 2 listed

• GHY6 – Merlin, built 1984, 32m diameter, fully operational but decommissioned

GHY1 GHY3 GHY6

GHY-6 – 410 Tonnes!

• Standard Intelsat design built by Mitsubishi – 3.6 ~ 4.2 GHz Rx

– 5.8 ~ 6.4 GHz Tx

– 10.7 ~ 11.7 GHz Rx

– 14 ~ 14.5 GHz Tx

• Cassegrain reflector with mirror tunnel feed – Drive a small car down the tube!

• Presents all feeds in control room – Ideal to connect up our EME

equipment!

Moving GHY-6

• 4 large motors drive it around a track

• 2 large motors for elevation

• Positioning system rather than a tracking system

• Programmed with 14 bit Azimuth and Elevation input.

• 14 bit encoders display the actual position to 1/100th of a degree.

Beam Waveguide (suggested layout!)

Goonhilly Dish GHY-6 – ‘Merlin’ – Performance (based on VK3UM calculator)

3400MHz

• Gain 59dBi

• Beam Width 0.2 deg.

• EIRP 43MW • 50W amplifier

• Signal at DX station 23dB • CW bandwidth

• DX signal at GHY-6 18dB* • CW bandwidth

5760MHz

• Gain 64dBi

• Beam Width 0.1 deg.

• EIRP 93MW • 40W amplifier

• Sig. at DX station 25dB • CW bandwidth

• DX sig. at GHY-6 21dB* • CW bandwidth

* - in theory see later – assumes DX station running same power to 3m dish

Would DATV work?

• DATV at 250ks would be 100 times weaker than SSB (2.5kHz BW) or 1000 weaker than CW (250Hz BW)

• But the major issue is phase distortion due to reflection off uneven surface of moon well as Doppler shift

• DATV did not work • tried AM TV and only saw weak

signal on SDR

Famous for 2.5 seconds

• BBC will be filming another series of Michel Portillo Great British Railway Journeys

• Goonhilly will feature in the programme that will be filmed in Devon and Cornwall

• Would it be possible to allow Michel Portillo to bounce his voice off the moon • The answer was yes

• In June 2017 G4NNS and G8GTZ set up the narrow band station and the result was broadcast on BBC2 TV in January 2018.

Two Days of EME

• In August 2017 we had the chance to use GHY-6 to have some EME contacts on the 6 and 9cm bands

• But we also carried out some important measurements on the dish performance for GES Ltd

• The main team consisted of Brian G4NNS, Noel G8GTZ, Tim G4LOH and Neil G4LDR plus Ralph G4ALY a visitor

• The objective was to work as many stations in as many continents as possible

• Contacts would be CW or SSB but no digital modes

Equipment

• 3400MHz Equipment • 144MHz IF transceiver

• 144 to 3400MHz Transverter

• On RX LNA (0.5dB noise figure)

• ON TX SSPA (50W O/P)

• 5760MHz • 432MHz IF transceiver

• 432 to 5760MHz transverter

• On RX LNA (0.7dB noise figure)

• On TX SSPA (40W O/P)

EME Day One – Included Press and Visitors

• Ready at moon rise to work Australia • Very short mutual moon window • First contact was VK3NX 9cm then 6cm

• Next contacts to Japan • Worked JA4BLC on 6cm (no 9cm allocation in JA)

• Then contacts with Russian Stations followed by Europeans

• No contacts with Africa • Little EME activity (and no one equipped for 9 and 6cm?)

• Finally South and North America • Including Brazil, Canada and East/West Coast of USA.

Some audio clips

• Our echoes on 6cm CW –

• VK3NX on 6cm CW –

• VK3NX on 6cm ssb –

• PY2BS on 6cm CW –

• G3LTF on 6cm SSB -

• Our echoes on 9cm CW –

• G3LTF on 9cm CW –

• K2UYH on 9cm ssb –

• G4RFR on 9cm CW –

• WA6PY on 9cm CW

EME Day Two – More EME Contacts and System Performance Testing • First conducted Sun and Moon Noise Measurements

• Replaced transverters with SDR receivers (Fun Cube Dongles)

• Used SpectraVue running in Continuum Mode

• Reception of distant radio source • Taurus A (associated with the Crab Nebula) was the target 6500 light years

away

• Positioned dish and awaited Taurus A to come into view

• It did not appear at predicted time! What was wrong. Then signal appeared later than calculated

• It was then realised that the GES Chief Scientist had used coordinates of his home location (east of Goonhilly) when calculating dish heading to Taurus A

Sun Noise calibration 6cm

20.5dB Sun Y Predicted 23.3dB

Taurus A measurement 6cm

1.7dB Taurus A Y (Predicted 4.1dB)

Why are some signals so weak

Big Dish illuminates only part of moon

Little dish illuminates whole of moon

Big Dish Little Dish Effect

• Total system noise will be approximately 200K i.e. up to 5dB more than a small dish (beam width greater than 0.5 deg)

• A small dish will see the whole moon surface

• Small dish will receive all our signal reflected off the moon

• But we only see about 1/25th of the surface of moon with GHY-6 • Due to very narrow beam width of 0.1 deg. (at 6cm)

• Hence we receive less signal reflected off the moon from the station with a smaller dish.

• If two GHY-6 size dishes attempt EME they would need to point at the same area on the moon.

The future for Goonhilly and EME from there

• By 2022 there will be a 50% short fall in the capacity of the ESA’s deep space network to support existing and planned missions to the moon and beyond.

• It was announced at the end of February 2018 that GES Ltd had secured £8.4M to upgrade facilities to support the ESA’s deep space network • This includes the refurbishment of GHY-6 which will start in late 2018

• In May 2018 it was announced that GES Ltd. had signed an agreement worth £24M to support a commercial moon lander programme.

• No more opportunities for amateur radio operation using GHY-6 • Or are there?

Acknowledgements • Goonhilly Earth Station (GES) Ltd

• Particularly Matt Crosby Chief Scientist

• AMSAT UK and BATC • For making initial contacts and gaining access to the site and use of the dishes

• TX Factor • For use of the video clips

• The EME community around the world • For the high level of activity on the 9cm and 6cm band using our third visit