Ultimate DX - Part III
The Physical Research Laboratory located in Ahmadabad, India had been monitoring a Soviet radio station broadcasting from Tashkent on 164 KHz. This was being recorded so that any change in ionospheric conditions such as caused by solar flares could be monitored. In the months from April to July, from 1960 to 1963, a sharp drop in signal strength was noticed that occurred progressively later each night. It was determined that as Sco X-1 passed over the midpoint where the signals would normally be reflected by the ionosphere, the X-rays from Sco X-1 would apparently ionize the D-layer causing the signal to be absorbed and the signal strength would fall off at the receiving site at Ahamadabad.
This type of observation would not be hard for anyone to make. By setting a receiver to a known beacon type signal, such as WWV on 20 Mhz, a frequency that normally goes dead at night, it would be possible to observe phenomena of this sort. By using a stereo tape recorder that has one channel used to monitor the other WWV signals found on one of the frequencies that are usable at night such as 5 or 10 MHz, any time that the beacon signal would come up, the tape recorder could be turned on by a carrier operated relay. This would allow the time of the beacon signal appearing to be noted and the length of the time that the signal stayed up.
This technique would allow the monitoring of other beacons, and if a chart recorder could be hooked to the avc line, a more permanent record of signal fluctuations could be recorded. By using an inexpensive two channel audio mixer, a single channel tape recorder could be used. There are variations on this theme, and this is only an example of what could be done with available off the shelf equipment. With inexpensive digitally tuned receivers that have a frequency readout accuracy of cycles and some even with timers and carrier operated relay outputs on the back panel, the ability of the amateur radio astronomers to make accurate observations has increased many times.
It is not too hard to get an S-meter calibrated accurately, if you have a friend with a good signal generator. As for frequency, if you can find your signal, then you are on frequency. Most of the under $200 (may be dated info.) Uniden Radio Shack and Sony digital keyboard entry receivers are accurate within cycles and finding a frequency in their tuning range is only a matter of keying in the frequency and hitting enter. The antenna requirements are minimal, depending on the frequency, a directional array might be appropriate, But for the most part an antenna for the frequency is all that is usually required.
The observations that can be made by this technique can include meteor pings and bursts, sudden ionospheric disturbances, solar flares and other ionospheric phenomena. There is also the unknown happening that can show up unexpectedly. This is where the individual observer can contribute vital information. As has been pointed out in past articles, the ability to make changes in the frequencies monitored, equipment and techniques is an advantage that the individual observer can put to good advantage.
The only problem that needs to be solved now is the exchange of data between observers. Real time data exchange between observers separated by states, oceans, or continents is one that must be solved before correlation of different happenings can be done. In the continental U.S. Compuserve and other large public access bbs networks is one possibility, as is the use of RTTY, Packet, Amtor, or any other emission available to licensed amateur radio operators would do quite well. The cooperation between non hams and hams would allow the rapid transmission of data all over the world.
It is possible that someone reading this could make a real contribution to the radio astronomy field as well as ionospheric research. Nothing is impossible. It remains to be seen what can be discovered. The quest for the unknown is one that should never cease. There is no more Terra Incognita for us to charge into and explore like the early explorers did when they went into Australia, Africa, South America, and other unknown regions of our planet. So the alternative is the Terra Incognita of our highly technical hobby, be it amateur radio, radio astronomy or shortwave listening. There is plenty for all to look for and discover.
Any one reading this and would like to contribute to this series is welcome to do so. Our vast number of personal computers, and people with the knowledge and ability to use them, as well as others with just as specialized abilities in the RF spectrum and other fields should enable us to make inroads into the unknown. There are many unknown things that happen for which there is no easy explanation. Long Delayed Echo are one that has mystified many who have heard them. There is nothing as startling as to hear your own transmission come back to you several minutes after you have quit transmitting. Where did the signal go at the speed of light for that interval of time? What sent it back to your location?
Before the cassette recorder became out, reports of LDE phenomena were not taken too seriously, except by those who had heard them. In one case, ten minutes after an Air Force Mars Net had been shut down, the entire net popped back up on frequency, and stayed there for the entire time that the net was on. The signals had the strange hollow sound that always characterizes signals heard on a dying band, very wavery and with a lot of flutter. As the “ghost net” came to an end the other signals that had been there at the same time as the net, gradually faded out, leaving a very surprised operator who would have given anything for a tape recorder. There was no way that it could have been a practical joke, as the frequency (15,715 MHz,) had gone dead just as the net ended and a total bandwidth of about 40 KHz had come back via the LDE. Those signals had taken a path 111,600,000 miles long by the time they had come back to earth. Where did the RF go? What caused it to bounce back? There is Terra Incognito in the RF spectrum, don’t let anyone kid you, there is a lot of it and a lot of it is located where exotic equipment is not needed to observe and record it.
So it is up to the intrepid independent experimenters who are always looking under rocks and other strange places to see what they can see, to keep looking under the rocks of the RF spectrum to see what they can find. It is hoped that the ranks of the radio phenomena observer as well as the ranks of the radio astronomers will grow as a result of these brief articles. The information exchanged between participants that will allow new facts about propagation and radio astronomy to be discovered, and maybe someone will make the ultimate DX contact with another civilization. It is only a matter of time.
Originally posted on the AntennaX Online Magazine by Richard Morrow, K5CNF
Last Updated : 16th March 2024