Upgrading the firmware of your Vixen StarBook on Linux

The first time this year that I tried to use my Vixen telescope on the Sphinx SX mount, I had problems. After selecting the last “OK” to enter scope mode, the display on the StarBook would freeze. This happened on the 2nd of January. Eventually, after removing the PCB in the mount and re-soldering the contacts of the DE-9 connector, thinking that the problem may be due to a dry joint, I discovered that the firmware version I was using at the time, i.e., V1.2 build 31, would not accept 2016! It may even have been a leap year issue.

I went to the Vixen website and discovered that there was an upgrade available, V2.7, which also happened to resolve some leap year issue. I downloaded the file, but then I was faced with the problem of how to upgrade the StarBook. I don’t use Windows; in fact, I changed over to Linux in 2006, never to look back again. But then I thought it might be possible to use Wine. I have the Linux-based Distro Astro operating system running on my laptop, and Wine comes pre-installed. (The quote below is from the Wine website.)

Wine (originally an acronym for “Wine Is Not an Emulator”) is a compatibility layer capable of running Windows applications on several POSIX-compliant operating systems, such as Linux, Mac OSX, & BSD. Instead of simulating internal Windows logic like a virtual machine or emulator, Wine translates Windows API calls into POSIX calls on-the-fly, eliminating the performance and memory penalties of other methods and allowing you to cleanly integrate Windows applications into your desktop.

Indeed, Wine did the trick without any problems. I simply connected the StarBook to my wi-fi router and entered the IP address assigned to StarBook by the router, in the upgrade installer.

Problem solved. I can use my telescope again!

Almost forgotten work on double stars

Alpha Crucis

Alpha Crucis

When I was Director of the Double Star Section of the Astronomical Society of Southern Africa (ASSA) I was granted permission to use the old McClean refractor telescope at the headquarters of the South African Astronomical Observatory (SAAO) in Observatory, Cape Town. At the time I was interested in using speckle interferometry techniques to measure separations and position angles of double stars. In 2001 I published an article about my work in MNASSA (Monthly Notes of the Astronomical Society of Southern Africa).

That particular issue of MNASSA somehow was lost, but I was very happy to discover a PDF version of my article, which had somehow survived several computer changes over the past 15 years. Anyone interested in double stars may download the article from the downloads page.

A 9th planet? Let’s sort the facts from the garbage

Please, let’s pplanet9ut the matter of a POSSIBLE 9th planet in perspective.

The astronomers, Konstantin Batygin and Mike Brown who recently announced their findings never claimed that they found a 9th planet. Instead, they suggested that a large body with 10x earth mass would explain the perturbations in the orbits of other objects in the inner Oort cloud.

Bottom line: a planet has NOT been found; only evidence that such a planet may exist. At this stage it is a hypothesis, and much data gathering and observation are needed to test the hypothesis.

Most of what one reads on the internet and in the media must be passed through a bullshit filter. The media are known for twisting facts. Very few journalists have the science background necessary for accurately reporting scientific findings.

So, where does one find reliable information? Here is one source which may be trusted: Scientific American. However, the scientific journals in which such findings are usually published, are the most reliable sources of all. In the case of¬† the possible 9th planet, the journal is The Astronomical Journal in which Batygin and Brown published their findings under the title “EVIDENCE FOR A DISTANT GIANT PLANET IN THE SOLAR SYSTEM”.

SID Programme Finally Started: The Antenna

antennaWhen I decided that SID monitoring would be an activity that might be interesting and worthwhile pursuing, I looked for information on the technique in general, and equipment in particular. I soon found that most of what is available is often very outdated and mostly put together by the observers themselves. I therefore decided to use whatever guidelines seemed sensible, and design my own system.

The first step was to design the antenna. Since loop antennas seem to be the norm in SID monitoring, I considered several ideas for a loop antenna which, besides the obvious need to do what it is supposed to do, would also be robust and look professional. It would appear that many SID observers construct their loop antennas on wooden frames, square frames being the easiest to construct. I took a different approach and constructed the loop antenna shown in the photo on the right.

The ring has a diameter of 1 metre and contains the loops of wire. For the ring I used a length of a new type of plastic plumbing pipe which is very strong. The wall of the pipe has two layers, and in between these layers is an aluminium foil shield which serves to prevent heat from being radiated outward through the pipe when it is used for hot water installations. This shield is a bonus as far as the SID antenna is concerned. Since small loop antennas respond to the magnetic field of received signals, it is desirable to shield the antenna from the electric fields generated by local man-made noise sources.

probesMy idea is to place the electronics at the antenna feed point in a suitable weatherproof enclosure. For this purpose holes for the ring were made in the enclosure which I decided to use. Next, the pipe was bent to form a ring and the two ends were passed through the holes in the enclosure, as the photo on the right shows. For the wire loops I used a 4-core single-strand cable of the type commonly used by installers of burglar alarm systems. This cable was fed repeatedly into and out of the ring at the open ends until it became difficult to add another turn. I managed to get 11 turns into the ring, which resulted in 44 turns of single wire. I would have preferred more turns, but 44 should be a reasonable starting point. Finally, the individual wires at the ends of the cable were soldered together in such a way that only the two ends of the resulting coil remained. During the soldering process each solder joint was covered with heat shrink tubing to prevent short circuits between joints.

Having come this far, the next step was to tune the antenna to the frequency in the VLF band which I hope to monitor. The NWC station at Harold E. Holt, North West Cape, Exmouth, Australia seems a good candidate, but this needs to be confirmed. Since this station transmits at 19.8 kHz I decided to tune my antenna to have maximum response at this frequency. First, the inductance of the coil had to be obtained, which I found to be 6.33 mH. Next, the required value of a parallel tuning capacitor to achieve resonance at 19.8 kHz was obtained from the formula

    \[ C = \frac{1}{L}\left(\frac{1}{2 \pi f_0}\right) \]

This gave a value of 10 nF.

The antenna was excited at frequencies from 10 kHz to 30 kHz using a GW Instek AFG-2005 function generator and a GW Instek GDS-1052-U oscilloscope to measure the voltage across the antenna terminals. The results are shown in the graph below. With the choice of five 2.2 nF capacitors making up the total parallel capacitance, the antenna has a peak response at 20.5 kHz. The response above the -3 dB level extends from about 12 kHz all the way to 30 kHz, so in theory it should be possible to monitor stations at frequencies other than 19.8 kHz. Of course there will be tuning in the receiver, but more about this when I get around to the receiver design.

fngen scope

antenna_response

Micro-controlled VLF Receiver

My recent receiver design (circa 2011), which has neither been built nor tested, was to have the following features:

  • Single 5V d.c. supply.
  • Gyrator-tuned.
  • Gyrator tuning and second stage amplifier gain adjustment by means of digital potentiometers.
  • Zero-crossing detector, precision full-wave rectifier, peak detector and d.c. level shifter.
  • Micro-controller (Freescale MC9S08SH8).
  • RS-232 serial port.

You can download the circuit diagrams from the download page and try out the circuit if you wish, at your own risk. The circuit comes with no guarantees:

Go to download page.

I now have other, more ambitious ideas for a receiver. But more about this later.