- Detta ämne har 3 svar, 2 deltagare, och uppdaterades senast för 1 dag, 10 timmar sedan av Jens Romeikat.
- 5 januari, 2016 kl. 20:22#4089DL2JMB Juergen BrustatGäst
SAQ has been built for communication with America
and has been successfully used until after WW II.
But according to recent reports from the USA and Canada
the reception is very poor nowadays.
So, what has changed ?
- 21 oktober, 2021 kl. 17:05 #9210Jens RomeikatGäst
Found this book after searching the internet:
”Die wissenschaftlichen Grundlagen des Rundfunkempfangs”, 1927.
There is a lecture by Prof.Dr. R. Rüdenberg to find.
On page 226, a diagram shows the field strengths over several days.
I translated with the help of ”google translate”
4. Influence of the atmosphere.
When transmitting over long distances, for example … from America to Europe, one observes great differences
in the intensity of day and night reception.
In general, daytime reception is poorer and there are particularly strong fluctuations in sunrise and sunset at
the transmitting or receiving station itself.
Fig. 45  shows a series of measurements of the course of the field strengths from distant stations, recorded over several consecutive days.
A fourth reason might be:
The background noise decreases at night, you can do that see the color change in the waterfall diagram of a Web SDR.
(while observing ”cutler”,USA during the night)
: Rem: ”W.Q.K” means ”Radio Central, Long Island (18,788 KHz), see ”wikipedia”
- 20 oktober, 2021 kl. 23:07 #9209Jens RomeikatGäst
A third reason could be that the telegraphic broadcasts of the major stations
took place at very long distances at night.
(Ionosphere, ionospheric waveguide)
- 6 januari, 2016 kl. 11:45 #4093Ola HernvallDeltagare
I think there are two main reasons for the problems of receiving SAQ in North America today.
The first reason is the receiving antennas used. As radio amateurs today can use antennas not bigger than their own garden, the antennas for receiving commercial telegram traffic were huge. The commonly used antenna was the Beverage antenna. The antenna in Riverhead on Long Island outside New York for receiving European transmitters was about 14 000 meters. It also had a facility to cancel local noise from nearby transmitters, thunderstorms and statics. More information on the Beverage antenna can be found here: http://www.nrcdxas.org/articles/WaveAntenna.pdf
The second reason is that the amount of man-made noise has increased over the years. Power lines, railways, washing machines, dimmers, all contribute to an increased noise level. At least in Europe, it seems that local noise is a worse problem than low field strength when receiving SAQ.