Summer Ground Station

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This is the project management page for the Summer Ground Station project. We managed to bodge together a 70cm/2m satellite ground station to go on top of the moonbounce truss for use at the EE dept summer event on 19th June 2014, whilst spending no money whatsoever.

Project summary and aftermath

Before starting a groundstation project, review the aftermath documents on Dropbox for moonbounce and this project.

Scaffolding and equipment required for base construction

  • 7x orange stage legs
  • 2x blue stage legs
  • 2x cyan stage legs
  • 1x 10ft aluminium
  • 2x 7ft aluminium
  • 2x fixed aluminium clamps
  • 12x steel rotating clamps
  • 2x key clamp "wing nut"
  • 2x swingy key clamps
  • 4x ratchet straps (short)
  • 1x big black rope, attached to base and used for raising
  • 3x-6x guy ropes
  • 3x-6x pegs, to anchor guy ropes

Original Project Notes: A lesson in messy documentation

Work Breakdown, Areas of Responsibility

Temporary system diagram

Radio: Abdullah & Phil
Mech: James & Steph
Elec: Laurence & Matt

Component Got? Tested? Responsible
Antennas Yes Yes? Radio
Antenna Mounts Y Y Mech
Rotator Y Y Mech
Mast Head Y Y Mech
Mast Truss Y Y Mech
Hideous Ground Support Structure (HGSS) Y Y Mech
Radio Y Y Radio
Radio Interface Y Y Elec
Rotator Controller Y Y Elec
Rotator Controller Controller (arduino interface) Y Y Elec
LNA Y Y Radio
Feeder Cable Y Y Radio
Antenna matching cable Y Y? Radio
PC Y N Elec

Initial Priorities

As of the initial project meeting on 20/05/14, the major priority is getting a dual-axis rotator working. Everything else depends on this, since without a working rotator it's kinda useless.
Priority list:

  1. Rotator & rotator controller
  2. Antennas & matching cable
  3. Rotator controller controller (arduino interface)
  4. HGSS
  5. Everything else.

Updates and Notes

Mechanical test lift results, 31st of May.

Radio: 6-9th June

  1. Power divider and switched phasing array has been constructed and somewhat tested for the 2m antenna.
  2. Both LNAs were tested and confirmed working.
  3. Power divider and switched phasing array constructed for 70cm, but someone did their maths wrong and the cables need cutting down a bit for it to actually work.

Electronic: 6 June

  1. Tested both rotators with electronics today. Arduino code needs polishing (LCD and feedback - rotctld 'p' command) and system needs calibration.

Mechanical: 1st-3rd June

  1. Secured a new motor from a printer
  2. Bob1 created us a beautiful shaft extender
  3. With much grease and balls the el-emotator was repaired

Mechanical: 31st May

The mechanical test lift day was great success! Nobody died or anything!

  1. HGSS design tested and finalised.
  2. Lift procedures and guying points worked out.
  3. Azimuth rotation and antenna clearances tested.

The To Do list for the next few days (up until Tuesday) is as follows:

  1. JT PH James and I are going to attempt surgery on the broken emotator motor Sunday afternoon - IF we can get into the case without destroying it, it sounds like the broken coil can either be fixed or bypassed.
  2. ALL Continue searching all the usual suppliers for a suitable replacement motor.
  3. PH AA Phone round ham radio suppliers Monday AM to look for a proper replacement Emotator motor.
  4. PH Email Tim Brown Monday AM to set up a BBQ meeting sometime monday/tuesday/wednesday.
  5. JT Email Security to confirm the date they've been given and change if necessary.
  6. ALL Monday Eve - take stock of the Emotator motor situation and decide whether to go Yaesu or not.

Mechanical: 30th May

Not a fantastic day -

  1. Elevation rotator jammed again and the fault was traced back to a burnt out motor coil.
  2. Unless motor can be replaced, the entire emotator system is no use to us for this event.
  3. Need to call some ham shops and/or try speccing a motor off RS.
  4. Whilst this happens, full steam ahead to try and swap everything out for the Yaseu dish rotator.

General: 29 May

After finally speaking to Carey it's revealed that the department doesn't have enough staff to devote someone to organisation.

  1. Carey today emailed security about the event, so we should have confirmation of date and place next week.
  2. We're going to have to organise food etc. which is a pain but not too bad

Mechanical: 28 May

  1. 2m antenna, 10ft truss section and fiberglass cross-pole are now at PH's house.
  2. Emotator assembled into single unit, attached to pole mounting plate.
  3. Pole mount to upper truss section tested. Could do with a slightly shorter pole, but it will suffice.
  4. Elevation rotator cable made.
  5. Antenna mounting hardware retrieved from Tilly.

Electronic: 24 May

  1. Found rotator controller controller box, minus Uno. Need to bring into shack and test it talks to the Emotator box again, but should be okay.

Mechanical: 21 May

  1. The rotators totally work! both emotators revolve and properly hit their range limits. Feedback is sketchy/not working properly and needs more investigation - it could be an issue with the rotator pots, the box internals or something else entirely. Work is needed between mech and elec to sort out what's happening.
  2. Also created documentation for the Emotator connectors because those were WAY too hard to work out.


Finish date: Wednesday 18/06/14
Event date: Thursday 19/06/14

Mechanics test lift date: Saturday 31/05/14

31/05 Mechanical Test Lift

The purpose of this lift is to design/build the HGSS and perform a test lift of everything that's going to be going on the truss (minus cables). We can then check everything is safe, and that rotation works okay with the antennas attached. We are then able to confirm procedures for setting up on event day.

For this we will need to have ready:

  1. Rotator!
  2. Rotator controller
  3. Antenna mounts
  4. Mast Head
  5. Mast Truss
  6. Hideous Ground Support Structure (at least a vague idea)

Shopping list (eg Things To Steal From Crew):

  • Steel Scaffolding
  • Spanners?
  • PATS Field power hookup
  • Rope?
  • ...

10/06 Radio/Electronics Test Run

The purpose of this test day is to do a full test run on the technical side of things. Get the antennas and rotator up on the small truss section in a field and test computer tracking, receive performance and decoding. Preferably over the course of an evening so we can pick up some known-working satellites (ie Funcube).

For this we will need to have ready:

  1. Rotator
  2. Rotator controller
  3. Rotator controller controller
  4. Antenna mounts
  5. Antenna matching cable
  6. Feeder cable
  7. LNA
  8. Radio
  9. Radio interface
  10. PC

Component-Specific Documentation/Discussion


  • 2m antenna has N-type connectors.
  • 70cm antenna has solder points, we're missing the connectors that're meant to go on it.

Antenna Mounts

  • 2m antenna has u-bolt mounting attached, missing a single nut.
  • 70cm antenna has nothing yet.
  • Both are sorted now.


Emotator instruction manual - EARS documentation page

Mast Head

Mast Truss



Radio Interface

Rotator Controller

Rotator Controller Controller

Found box, all there. Needs an Uno. Then interfacing with eiter the feedback from the emotator box or the rotator directly.


The 2m LNA is an Advanced Reciever Research MSP144VDG-160. It supplies 24dB of gain at 144-146mHz. The power supply is 10-16v DC. Wiring scheme is yellow/green = negative, orange = positive. Don't ask me who wired it up that way! Everything tested and confirmed working.

The 70cm LNA is an Advanced Reciever Research SP432VDG. It supplies 16dB of gain at 430-440mHz. The power supply is ~12v (13.8v). Everything tested and confirmed working.

Feeder Cable

Antenna Matching Cable

Essential: We need to make impedance matching and polarisation cables for each antenna, this will fix each antenna to a single circular polarisation direction.

Very nice to have: A switch box which allows us to flip between left-hand and right-hand circular polarisation on each antenna. Should be doable using either coax relays, or coax rotary switches + a motor for control.