UPDATE ON THE SARL/HMO 40m BEACON PROJECT
18 March 2008
Introduction
This document details an update on the status of the 40m beacon project. The beacon project is a national system of beacons on the 40 metre band operating on a single frequency. The aim of this project is to provide a convenient tool for Amateur Radio, Ionospheric Researchers and Educational Institutions where Amateur Radio outreach is being implemented. This report details the status of the project.
The beacon project is a national South African Radio League (SARL) project operated in collaboration with the Hermanus Magnetic Observatory (HMO), a national facility of the National Research Foundation (NRF), and volunteer Radio Amateurs around the country.
Technical Update
The technical design aspects of the beacons deployed in the SARL 40m beacon project are being handled by John, ZS6EF. To date we have been very busy with the technical aspects of the 40 metre beacon project and this is an overview of what has happened and what we see as happening.
In November we deployed 6 beacons as a first test flight to see what surprises were waiting for us in the field. The design of the following additional items were undertaken,
· GSM Modem and Interface unit.
To be able to program messages into remote beacons for use by SARL and HMO to put messages on fitted beacons by SMS.
· A Telephone Audio Interface.
To be able to reprogram beacons remotely by telephone thus changing slots and starting times and to calibrate time walk.
· Telephone base Interface
To be able to talk to a distressed or faulty beacon.
· Design of a Digital Receiver.
Monitoring the 7.023 MHz frequency on a continuous basis is an impossible task for anyone. We need manual reporting to provide students with the experience of scientific reporting and to make use of operator experience. For the HMO scientific modeling project we need a complete record of the propagation in each area. In addition we see the receiver being a great asset to Amateur Radio for predicating propagation locally specifically during emergencies. This unit monitors the 7023 kHz frequency and logs the call sign, RST 4 beep result, time and date. When the memory is near full a led light indicates that the unit should be plugged into a USB socket. A date.txt file is then produced of the log. This can be sent to the HMO and used by the beacon companion.
· Windows Beacon Companion Program
This program uses the date.txt file produced by the Digital Receiver and gives the advantage to an Amateur to calculate real time propagation to any part of the RSA. Prediction and propagation studies will then be available with real time results plotted at the Amateurs shack. Special facilities are planned for those 40 m beacon project Hosts.
· Support to Other Amateur projects
These include- RTA- Bacar – Web related tasks – 2m beacon project.
At the moment the plan (should everything go according to plan) is that we would start to deploy the next 22 beacons in the first week in April.
In the field at the moment the 6 beacons deployed displayed the following characteristics.
1.0 Spasmodic frequency drifts late in time depending on location.This was found to be due to the schottky protection diodes on the input pin of the microprocessor rectifying external RF and lowering the DC bias on the gate down below the schmitt level thus stopping the inverter from oscillating for the time the RF level was present.
2.0 Difficulty in setting the slot and start time and a long wait before being able to start.
3.0 We did have 5 direct lightning strikes on the ZS6SRL beacon which we encouraged. Each strike destroyed something but not the Beacon. The 5th strike in December destroyed the standby batteries but not the beacon. For this we are well pleased.
A document was produced and posted on the SARL web site showing what our objective were and our solutions are to cater for these deviations. Different types of solution were investigated using the internet, GPS clocks, and precision clock chips. In terms of our mandate the internet did not fit the model.The GPS clock was a super standard and we tried hard to utilize this standard.The problem with the raw GPS clock is that it does not have a real time function.This would solve the time walk problem but still left us with the setting problem. Eventually we decided to keep it simple and use a precision real time clock chip. After testing many types and eliminating one after the other we decided to use the Philips PHFPCF8563TF4T3. This unit will give us the best available stability and give us the facility to correct the time if necessary.
The beacons were then rebuilt with a LCD display to show actual time and buttons were provided to correct the time. The starting time and slot time were then set in the firmware against call sign so there would be no settings of these parameters except by digital download. All the Host has to do is check the time is right on the clock display. This has solved the problem encountered in 1.00 & 2.00 above but has presented an additional problem.The additional problem is centered on the digital correction value within the Philips precision clock chip and what value to set.
It takes a considerable running time to determine what the correction value will be after calculations determined from the first run. You then enter the new value and run again and see if it is right. At the moment we have a system advised by Philips that will quickly determine this value but we have to prove the system. After correction we have to run the beacon for a long time to ensure that it is correct. The alternate would take several weeks to calibrate a clock. At the moment the results are very good and the stability of the clocks is excellent. We have two beacons on the ZS6SRL call sign sharing the sending one after the other and staying perfectly in sync. You are actually hearing different beacons on at different slots. Now we have a time schedule that looks like this.
March | The Cape Town RTA |
| April | Several units will be calibrated and the 6 beacons now on the air will be replaced. |
| May | Bacar Testing, The KZN RTA, & Port Elizabeth RTA |
| June | Overseas Trip (no beacon design work done) |
| July | Issuing of the balance of the beacons for phase I. |
| August | The evaluation of the Digital Receiver |
| September | The Gauteng RTA and the deployment of the Digital Receiver and Companion Software. |
To date we have spent our precious time in the following way since December.
430 hours on design work
60 hours on manufacture
40 hours on things that did not work
20 hours supporting other projects
5 hours replying to questions
HF Propagation and Ionospheric Research
One of the main aims of the 40m Beacon project was to utilize the beacons to
a) obtain a real time propagation indication, and
b) to build up a database of propagation information that could be used to validate existing propagation models and, hopefully, develop a South African model.
At the moment with only 6 beacons on the air a number of people have been monitoring them on an ad-hoc basis and sending in their reports to the HMO. We are really grateful for this and assure everyone who sends in a report that these are being collected.
A number of people, including the beacon project team, have been listening to the beacons and using them to determine propagation paths. So, this aim is at least happening. The current method of beacon reporting is not ideal, however we are working on newer more efficient ways of reporting.
Because of the busy schedule of the beacon project team, the real propagation work has not started yet. Once all the beacons are on the air, there will have to be a standard for sending in beacon reports, and we plan to locate automatic digital receivers in strategic locations to add a 24 hour consistency to our database.
In January 2008 a MSc student began her project at the HMO which entails looking into the validating of the current HF propagation projects and making use of the beacon project results to validate her results. We are hopefully that this project will lay the foundations for improving the current HF propagation results.
Education and Outreach
Another aim of the beacon project has been education and outreach. There are many potential spinoffs for education and outreach from a project such as this, for eg:
1) school groups can be coordinated to listen to beacons at different times of the day and send in reports. A competition can be set up for the most recordings etc.
2) science centres with amateur radio stations can be tasked with monitoring certain propagation paths, and learner activities can be designed around such propagation.
3) Learners who have recently obtained their amateur radio license can be utilized as role models and asked to coordinate receivers in their schools.
4) Decode the message competitions can be set up on 3 of the beacons and restricted to school groups. These are just a few ideas that we have had.
However, the beacon project team has had very little time to implement this and it looks as if even less time will be available in the future. Therefore, the project team is looking for someone who is keen to work with learners and science centres and look after the outreach aspects of this project in collaboration with the current team.
Conclusion
It has been 5 short months since the beacon project was launched and in that time we have had ups and downs, which basically means that this project has been running like any normal project.
The beacon team are working flat out to correct any problems and to ensure that when phase 1 is completed we have a good efficient well working system that is of benefit to everyone.
We would like to thank all the beacon hosts and potential beacon hosts who have offered us their assistance in hosting and monitoring the beacons. For us this resembles real HAM spirit, where we all join in positively and make Amateur Radio a great community to be involved in. Should you have any queries, please do not hesitate to contact us via email at beacon@hmo.ac.za
73
The Beacon Project Team
