Saturday, March 23, 2019

Presentation: Satellite Spectrum & Amateur Radio

Steve K2GOG presented on "Satellite Spectrum & Amateur Radio" at the Trenton Computer Festival on March 23rd alongside another 50+ technology and innovation focused topics.

The goal of the presentation was to cover the valuable radio spectrum available through amateur radio and promote its use through innovative communication applications on earth and in space thanks to underlying computer technology

How much spectrum do we have?

For those that are already licensed amateur radio operators, you may have a printed version of the below spectrum chart that the ARRL publishes or at least have seen it somewhere before.

In the United States and most other countries, there are different license classes of amateur radio operators. Some countries restrict the transmit power or operating modes as well as what frequencies can be used depending on your license restrictions.

Steve decided to add up all the spectrum that is accessible to the three current United States amateur radio licenses and further highlight just how much of the total 23,126.7731 MHz of discontinuous spectrum can be used for satellite related communications. The results are pretty interesting.

What really separates the Extra from General or Technician?

Sometimes it is good to be simple. Get the highest license possible and ensure you never have to worry about operating on the wrong frequency. Currently, the only thing that separates the highest from the lowest license class in terms of spectrum access is 3.9321 MHz of operating capability.

The difference in spectrum for the different license classes is mostly found in the HF bands ranging from as low as 135.7 kHz and up to 29.7 MHz. The only other spectrum not accessible to the technician class license is the 219 to 220 MHz portion of the under utilized 1.25m which many consider as being only from 222 to 225 MHz.

The remaining spectrum is all available to the Technician class license holder!

What if your not interested in long range "HF" communication?

With advances in radio receiver sensitivity and advanced low signal to noise ratio transmission modes, large antennas often associated with HF operation are not always needed.

However, even with specialized magnetic loop antennas and FT-8 digital text modes -nothing beats a full sized dipole for global communications on the 14 MHz or 7 MHz bands often referred to as 20m and 40m respectively and not everyone has the space or interest in such an antenna.

Radio propagation theory does not always guarantee communications are possible at all times of the day which may frustrate some people who only have limited times to "play radio" with HF spectrum.

RF HF propagation is just like the weather

A forecast is still just a forecast and is generally correct, but the difference between satellite communications and HF is the predictability.  For those with limited time to gain "radio communications" gratification, satellite communications may be worth a look.

You can easily calculate when a satellite will pass over head in the case of the "Low Earth Orbit" satellites covered in Steve's presentation for example. It certainly would be great if the weather was like that, wouldn't it?

Depending on satellites

One shortcoming of most satellite communications is that you are reliant upon a man made piece of technology flying over your location in order to make long range contact.

The other shortcoming is you can only make contact with other stations in the footprint of the satellite, which is different than HF since technically you can talk around the world and sometimes even hear your own echo under the right conditions.

Benefits of satellite communication is that you can get a lot of "ham radio" done in a very short amount of time given the brevity of low earth orbit satellites for those not fortunate to live in the foot print of the only current geosynchronous satellite that covers all of Europe, Middle East, Africa, India and a few other countries across Asia.

Fight:  Innovation in amateur radio

The first amateur satellite put into orbit was OSCAR-1 in 1961, just 4 years after Sputnik was put into orbit as the first ever satellite. 

Now almost 60 years later, there has been a total of over 100 satellites put into orbit and most of them being fully operational, with a few example success stories being AO-7, SO-50, AO-92 and QO-100.

In total and thanks to international regulatory efforts, all this satellite success requires spectrum to be set aside since managing who or what can use certain frequencies is more challenging compared to how a specific country can manage its finite spectrum resources.

Its pretty clear that there has been a lot of innovation within the amateur radio satellite spectrum, but much of it has yet to be fully realized.

One example of how technology originally meant for meteor scatter or earth-moon-earth communications which involves bouncing signals off of these non-man made satellites is known as low signal to noise ratio modes, mostly invented by Joe Taylor, K1JT.  The modes can now be found in use on the HF bands rather than for space related contacts. Here is how computers and amateur radio together create innovation.

Technology Improvements: We all benefit 

OSCAR 100 which was put into functional orbit by the Qatar Amateur Radio Society along with technical guidance from the German branch of the Amateur Satellite Corporation known as AMSAT pushes the boundaries of technology and spectrum management.

In 2018, various digital voice modes such as those enabled and made more accessible due to Multi Mode Digital Voice Modem (MMDVM) hot spot devices created an issue for certain satellites operating in the congested 435 to 438 MHz band.   A LEO satellite such as AO-92 speeds overhead at an average altitude of 220 miles and can easily be interfered with by 20mW hot spots and the lower power radios people use to access them. OSCAR 100 is the only satellite that does not have this issue.

Price has driven the adoption of MMDVM hot spots and radios such as the Anytone D868, TYT MD-380 and others. 

Today, thanks to the QO-100 satellite, there is a lot of rapid innovation taking place which shows that cost and user benefits generate lots of excitement that highlights the growth of the radio arts as specified in FCC Part 97.1.

The only unfortunate thing for North American amateur radio operators is that its not possible to utilize this innovative satellite and its great use of spectrum because it is in geosynchronous orbit. However, the AMSAT project GOLF is coming near which is exciting!

Looking beyond, satellite is just one way to show innovation through the use of spectrum. The future of amateur radio is dependent on finding other innovative applications for spectrum, so why not look at what else may be possible outside of the HF bands, even going as high as the mmW bands -
GigaHertz.... not MegaHertz!!!

Full Presentation & Added Bonus

The complete, but non-animated version of the presentation can be found at the link below in addition to the amateur spectrum database compiled to help develop some of the content Steve K2GOG presented both at the HVDN Quarterly meeting this past March 11th as well as TCF on March 23rd.

1 comment:

  1. Thoroughly enjoyed the presentation – de Jim, WA2UMP


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