Progress report 7th. Jan 2006
By Fred Kennedy, ZL1BYP, Project Leader.
Work throughout 2005 has been largely concentrated into 3 areas: the U/V Linear Transponder, the Integrated Housekeeping Unit (IHU) and the Attitude Determination and Control (ADAC) system.
In July, on-going support circumstances set a firm time line on the IHU and the linear transponder. A working prototype of both units was to be in the thermal vacuum tank by Christmas Day!
With most of the design work for the linear completed our PCB designer Kevin Horsburgh pulled out all the stops and by mid October we had a set of Gerbers on their way to Sierra Proto Express for the Preamp, Receiver and Transmitter. And a real pressure cooker effort underway to assemble the component set!
Of particular concern was the necessary NDK band-pass filter which seemed to be widely advertised but completely unobtainable from all of the recognized sources. We were almost at our wits end when Sangat (9M2SS) performed a small miracle and within a few weeks we not only had 3 but they were sponsored by Astronautic Technology (M) Sdn Bhd. A marvellous response and one for which we are very grateful.
This, I think, really gave us the lift we required and the rest of the parts arrived from various parts of the World in short order. (Some we unfortunately had to pay duty on!) However, with the bits in our hand we again fell on our feet with TMD Consultants, an Auckland RF development company, offering to assemble and test the boards using their well equipped laboratory. The CEO, Dr. Phil Wakeman, personally undertook the work and a great job he made of it.
To the credit of the circuit designer, Terry (ZL2BAC) very little modification was found necessary and Phil had the boards going and up to design specifications in double quick time. With the exception of the pre amp board, Fred (ZL1BYP) wrapped custom built screening round them and with the whole assembly on an adaptor plate it was ready for installation in the vacuum tank at Massey University by mid December.
It was decided that the preamp – which worked perfectly but was a prime item to be reduced in size to save space and weight – would not get special treatment and a standard die cast box was considered OK for the prototype. This – along with the other units - is pictured.
A small identification/beacon keying unit was provided for the transponder by Kelvin (ZL3KB) and “ZL6SAT KIWISAT LINEAR” went on the air initially attached to the main antennas at Fred’s station in Whangaparaoa, 40km north of Auckland. Ian (ZL1AOX) and a number of the other locals in the Auckland area worked through it very successfully over the next few days.
So, by dint of hard work and the determination of all concerned the date was achieved and Fred (ZL1BYP) spent the morning of Christmas Eve installing the unit in the vacuum tank, subjecting it to its new environment for the first time. As this is being written the transponder is connected to the skeleton mockup antenna (see the picture) and it’s working round the clock from the vacuum tank. The beacon is providing a very good signal into the ZL1BYP shack some 30km from the very low lying and heavily screened lab in which it’s situated. 50km in the other direction, Ian (ZL1AOX) also has good copy.
Much testing has still to be performed but so far the system has been given ‘the big tick’!
The IHU took somewhat second place to the major effort on the transponder; it was not neglected though.
Designed by Lyle (KK7P) and as reported in the October 03 report, converted into its final PCB layout by a Wellington team of 3 volunteers (Simon Peacock, Nick Payne and Kevin Horsburgh), the multi layer boards were obtained in November 2004.
With again a tremendous effort by another Terry (ZL3QL) - the AMSAT-ZL President - very ably assisted by others including Lyle who really swung in behind our guys – a complete set of parts for two processor and two RAM-DISK boards were collected. Unable to find a volunteer to populate the boards we had to pay for their production but a very good result was obtained despite a couple of small solder bridges which threw us into confusion a little when we started the set-up. Not having ready access to a suitable e-Eprom program burner in both Auckland (where the software test programs were being prepared) and Wellington (where the two units were being run up), progress was slow and the completion date was coming up fast.
Our software colleague Austin Green – a volunteer who answered our calls for programme assistance some three years ago – was providing the various test codes which had to be sent to Wellington for burning and trial. This was proving a turgid system so he changed tack to produce the circuitry for a suitable burner for local use. This was duly constructed and Austin switched emphasis again to produce the user software.
In response, one of the two IHU boards came to Auckland – initially to be set up to work the test facility but a few days single stepping the IHU clock revealed a common fault in the boards. This breakthrough - in early December - put us right back on track with the IHU and we installed the IHU – running a very simple looping task - alongside the transponder on 23 December. That is also running round the clock as I write.
Much more software development work is required to set-up the IHU and that is expected to start in a month or two.
The “Science Package” (ADAC)
We were very fortunate early in the year when a recently retired electronics/physics professional, Dr Jon Henderson came out of retirement to undertake some ‘fill in’ 1st Year Physics lecturing at Massey University. Fred (ZL1BYP) who is attached to that Department was ever looking for the main chance. The subject of satellite attitude determination and control was frequently discussed over coffee at the University Ground-station (ZL1MUA) and in the staff room. As a result Jon expressed a very positive interest in becoming involved in the opportunity for some “real physics experimentation in what was a previously un-accessible environment”. Indeed! What an opportunity! And what luck for us!
Jon – now back in retirement - has put a tremendous amount of time and effort into the mathematics of the ADAC experiment we are going to try with “KiwiSAT”. He has expressed confidence that we could indeed come up with a viable attitude control system! His graphical demonstrations using a mathematics software program really impressed and I have a feeling that Jon, Austin and Aparna (Badve) a volunteer from the University e-commerce section at Massey, will really set things alight when they, as a team, look at the software for the experimental side of the satellite. Neither my math nor my (almost total ignorance of) software engineering is up with the hunt but I’ll certainly be supporting where I can!
Overall there have been a number of other ups and down during the year some of which remain unresolved.
A definite ‘up’ is the FM Transmitter and Receiver. The Transmitter design by Kelvin (ZL3KB) is complete and the PCB’s are currently waiting for the component outfit to be completed and someone to assemble the prototype. The Receiver design is also complete and the PCB layout is sure to be another successful contribution from Kevin Horsburgh who is also engaged in the L Band down converter - just to keep himself busy! I have visions of all three of those items being up and running by mid year.
Another plus is the matched and flyable battery courtesy of the AMSAT-DL team – a spin off from their Express project. These have taken the pressure off the ‘cell selection process’ started with the donation of the initial batch of Suppo NiMH cells by Ian. In fact, all is not absolutely final on the battery front. Other AMSAT groups are looking at the very attractive performance of Lithium based products and we have the necessary analysis set-up to join that drive. As a background activity, and as time permits, we may well do that. (By the way - thanks, Ian!)
On the down side, we had selected a high efficiency (28%) solar cell on “KiwiSAT”. To accommodate these we needed to redesign the space frame to take what were larger cell pieces – an increase of just 7mm all round the space-frame. However, as often happens, one change leads to another. After previously ‘highly desirable but shelved’ improvements were added, we regressed about 80% towards a clean sheet of paper! To our dismay we have been advised that the selected cells are now subject to export restrictions and our expected total outlay for the cells would just about be eaten up by the license to buy them – payable just to have our application considered! So, we are looking for other sources of similar cells, hoping that the sizes will be standard and that another redesign will be unnecessary. Of course we trust that the efficiency will at least be in the mid 20% bracket. Fingers firmly crossed on that. (I don’t fancy doing a third engineering mock-up for yet another cell configuration!)
Efforts to find a suitable Operating System for the satellite computer control unit (IHU) continue to be frustrated by international protocols. Our search continues with the last resort of getting an OS locally written from scratch. The latter course could take a couple of years – after which we still have to find a launch and the finance to pay for it. (Financial expedience dictates that we finish the bird and then start to look at the big ticket item – the launch. This is an all volunteer project remember and individual circumstances can change! We cannot commit to launches when we cannot be absolutely sure we have a fully viable bird ready to fly!!)
The Black/White camera that we hoped to fly is also still very illusive. No one seems interested in taking that on. A fairly straightforward little ‘block’ one would have thought. Perhaps that’s the problem; a greater challenge is needed. Anyway, we are still looking and remain hopeful.
All in all some very good progress this year and by this time next year, if we can maintain the momentum, we will be well into the project. We are still looking for volunteers and money is – and always will be - an ever increasing concern. So far it has not been a limiting factor but the coffers are now pretty low and whilst we can ‘make do’ and wait for such things as the solar cells, the final space-frame and antenna units, we have to finance the build of the other systems ‘up front’.
There is still much to do – so please back us and join in.
We are getting there and will do so more quickly with increased interest and practical help.
Last updated 06/01/2006