Overview
After experimenting with the GB3RAL logging program written by G3PLX I thought it would be an interesting challenge to put together a system that could log the beacon for extended periods whilst I was out of the shack. As I have a broadband internet connection which runs H24 I decided I could share this information over the internet inreal-time. I already had most of the equipment sitting around begging for a task to do, so it was just a case of glueing it all together with the right combination of hardware and software.
I found after starting this project that another amateur, G4ZFQ already had a system up and running so I used this as a source of inspiration.
Update 28th November 2004: Magnetic loop antenna. Using a MSF receiver with TARDIS
Update 11th March 2005: Now using Chilton FoF2 data as Fairford availability seems limited.
Update 21st April 2007: Changed to a SOFTROCK receiver.
Update 4th February 2008: My own system is presently offline. Hopefully it will return later this year. If you are interested in participating in this experiment I'm more than hapt to provide advice and encouragement. If you would like to run a real-time system then please feel free to make your logfile available so I can add it to my comparisons page.
Equipment
Can be divided into two categories very easily.
- Radio equipment
- Computer hardware and software.
Receiver - Up to 8th April 2007
I used the AOR AR7030 receiver for monitoring. It is extremely stable, having a TCXO (temperature compensated crystal oscillator) for the master reference. It also has the facility to completely switch off the AGC and set the gain manually, as required by the GB3RAL program. The AR7030 is also capable of remote control via RS-232 so it can be controlled and monitored from the PC if required.Between 8th March and 21st November 2005, I did try my own design home-made receiver based on the (now obsolete!) Plessey SL6440/SL6700 ICs. This started life as a 160m SSB receiver, until I replaced the VFO with a 4833.5kHz crystal oscillator and fitted a 3-pole 5.29MHz RF filter. I ran this receiver for short period but had some temperature-related drift problems with the cheap 455kHz ceramic resonators used in the BFO circuit. This drift was so bad that it was outside the tracking range of the beacon monitoring software.
Receiver
I am now using a SOFTROCK LITE V6.2.For this task, the difference in performance between this and the AR7030 is barely noticeable. However, at around £20 to build, this is considerably cheaper than tying up any of my other receivers or transceivers.
The SOFTROCK is a direct conversion receiver designed for Software Defined Radio (SDR) applications. It has two audio outputs (phase and quadrature) and Peter G3PLX has now updated the GB3RAL software so that is supresses the unwanted sideband image. After careful setting up I can achieve 70dB supression of the unwanted sideband.
My only reservations with this simple receiver is it's lack of front-end selectivity. This isn't a problem with my tuned loops but could be with a wideband aerial such as a dipole.
For more details see the SOFTROCK 60 page.
Aerial Systems
The first aerial was somewhat poor, but then I wanted something that would represent what is commonly used in a cramped, noisy urban location. I used approx 10 metres of wire, end fed via a LAKE CT400 magenetic balun transformer and then fed to the receiver via 7.5 metres of RG174/U coaxial cable.This was replaced (8th March 2005) with a 1.5m square magnetic loop antenna. Two have now been built - see the Magnetic Loop page. These are located outside the house and fed back via 15m runs of coaxial cable.
Aerial locations have been optimised to compensate for noisy neigbours.
Computer Hardware
The PC in use is a Compaq Deskpro EN2. This is a small footprint Pentium III system with on-board sound and graphics. It has 128MB of memory and a 4GB hard drive.The on-board soundcard (ES1869 chipset) only provides mono microphone input, so I use an additional PCI card with a Crystal CS4281 chipset. Audio signals from the the SOFTROCK requires two channels of audio for the in-phase and quadrature signals, but the on-board mono input can also be used for a conventional SSB receiver.
Computer Software
Lots of this!The Operating system is Windows 2000 Professional.
Originally It started out with Win98SE which seemed to run out of system resources (down to 6% free after a week!). The beacon monitor program should run on anything from Win95 onwards.
John GM4SLV tells me it runs well on Linux under the WINE emulator and I have tested briefly on FreeBSD 6.2
Running on this box are the following programs...
- GB3RAL.EXE - the main monitoring program.
- RXWINGS2 - This is a freeware remote control program for the AR7030 (and other receivers).
- TightVNC - this allows me to monitor and control the system remotely on the home network and in conjunction with...
- ZEBEDEE - a secure encrypted tunnel program, I can view or control the system from anywhere with an internet connection! Runs as a background service under Win2k. I was previously using REALVNC version 4 but have noticed bugs when changed to Win2k - the right mouse button was being interpreted as the left button at the remote desktop!
- TARDIS is
a network time client program. This ensures
the PC clock is maintained to within a second every hour or
better. It uses either
a stratum-2 internet NTP server or an MSF clock module connected to the serial port.
This is not essential for correct operation of GB3RAL.EXE as it tracks
the beacon times (Thanks Alan G4ZFQ for pointing that out...).
Tardis will work with a simple MSF clock such as the Jonathan Buzzard design. This uses MSF hardware readily available from Maplin, or if you are creative like me then get a cheap MSF clock and borrow the radio module! See my TARDIS with MSF page. - I found an excellent cron program for Win2k - PyCron. This allows much more flexibility than the AT command. It runs a ftp script which uploads the logfile to the website at 4, 19, 34 and 49 minutes past the hour. Rather a large download and I could probably have managed wth its much smaller predecessor, cron.
As already mentioned, GB3RAL.EXE can be run under the WINE emulator - this means you can do all the processing with your favorite free Linux / Unix utilities. Who will be first to run it on an Apple Mac?
Click on the image below to see the latest S/N chart:
Data Processing
Since Peter G3PLX has updated the monitoring program the logfile format has now stabilised allowing me to do some online processing of my own. I wrote some rather crude php scripts which process the logfile to decode the most recent line. I was also uploading screengrabs generated by M0KGK's program. After some searching I found a php module called PHPlot, this produces png graphs on demand from a webserver. I managed to write a short script which processed the logfile and outputs data to phplot in a suitable format. This was used for the original 48 hour graph plots on my latest beacons and comparisons pages.
I have since replaced PHPLot with a more versatile graph library, JPgraph. This does all the graph plotting and is far easier to program than PHPlot!
The next step was to get other stations to make their logfile available on the web and use my script to produce a page showing (almost) real-time comparisons at different locations. Thanks to G4ZFQ and GM4SLV I now have (almost) real-time comparisons from the Isle of Wight to the Shetland Islands available HERE, this now includes recent foF2/critical frequency measurement from the Chilton ionogram. I'd welcome data from anyone else, you do not necessarily have to hold a 5MHz NOV or even a transmiting licence to participate.
Another method of processing involves importing the data into an Excel spreadsheet produced by G4ZFQ as part of his monitoring system.My own preference is an online MySQL database using the entire data set from the Fivemegs experiment. You can find details via the Logfile Processing page.
If you'd like to see the latest logfile from GB3RAL.EXE then please click HERE, or you can follow the Latest Beacons link.
I have also created a page for Archived Log Files dating back to September 2004.
Distances
- GB3RAL (IO91IN) -> G4IRX (IO92JV) = 148km
- GB3WES (IO84QN) -> G4IRX (IO92JV) = 207km
- GB3ORK (IO89JA) -> G4IRX (IO92JV) = 692km
Online distance calculator by G0HZK. Check out his other excellent distance and grid calulators.
Credits
Without whom the project might not have got this far...- G3PLX for the beacon monitor program GB3RAL.EXE
- G4ZFQ for doing it all already and documenting it on the internet
- G3CWI for suggesting a simple, but very effective automated screen grabbing program.
© Nick B. G4IRX. Last update: 04 February 2008 17:13. UTC