Dave, EI3IO, reports that the Falkland Islands Telecoms Regulatory Body has granted access for radio amateurs to the 4-metre band from 70.000 MHz to 70.500 MHz using a maximum power of 1 kW on a secondary basis since 15 November 2019.
The Falkland Islands (VP8) is now one of the few countries in the southern hemisphere with access to this unique VHF band. The map below shows the countries that have some form of access to the 4-metre band.
Red & Blue = Countries with some form of access on 70 MHz
What is perhaps unique about the 70 MHz allocation in the Falkland Islands is the sheer isolation of the location. There are no countries within a normal one-hop Sporadic-E range of the islands and indeed, the closest other radio amateurs on 70 MHz are probably in South Africa, a distance of some 6,200 kms!
This raises the very real possibility that contacts outside of the Falkland Islands may not be possible on the band.
The most likely possibility if at all would be a multi-hop Sporadic-E link across to South Africa but it would probably require 3 hops at 70 MHz which isn't easy. The other possibility is St.Helena in the South Atlantic but this is almost as far.
There may be a remote possibility of Sporadic-E link to some Trans-Equatorial Propagation (TEP) to the north but this seems unlikely.
On the fourth Tuesday of every month, we have a local net on 70cms about digital radio. While its primary purpose is to generate some activity on the local DMR repeater and talk groups, the conversation this month turned to the subject of digital voice on the HF bands. It was then that the digital mode FreeDV was mentioned and I have to admit it was the first time I had heard of it.
Perhaps I had come across it before in a news item and I didn't take much notice but it sounds like an interesting mode. It seems that while it started back in 2012, it's only in more recent years that the performance has surpassed that of SSB when the signals are very weak and in the noise.
I thought it might be an idea to put up a blog post so that perhaps a few more people might be interested in trying out this new mode.
My first question I had about this digital mode was how could it possibly work on the HF bands with all of the multi-path interference and fading? Well, it seems as if it's not a case of all or nothing. The signal is broken up into separate sub-carriers and the information is modulated on these by phase shifting.
The modulation mode is OFDM which stands for Orthogonal Frequency Division Multiplexing. The spacing is chosen so that the subcarrier nulls coincide with the peaks of other subcarriers. By doing this, the subcarriers don't interfere with each other.
It works on the principle that even if there is some selective fading on some of the subcarriers, enough information is getting through on the others to allow a conversation to be held.
Waterfall display of a FreeDV signal showing selective fading
FreeDV... What it is and what it's not
First of all, what it's not. It's not for DX-ing, chasing DXCC countries, contesting, chasing squares or awards. It's not there to replace SSB or even your local net on HF.... (for the moment ;o)
COMREG, the Irish licencing authority defines Amateur Radio as follows..."The amateur service is defined by the International Telecommunication Union (ITU)1 as: A radiocommunication service for the purpose of self training, intercommunication and technical investigations carried out by amateurs, that is, by duly authorised persons interested in radio technique solely with a personal aim and without pecuniary interest"
The self training and technical investigation aspects are what FreeDV and digital voice are really about. It's a new technology that is evolving and will appeal to people who want to learn about new developments and how they might be implemented.
The big advantage of FreeDV is that you can use it with existing HF radios with SSB. It's not like DMR, C4FM or D-STAR which require a completely new radio to be bought. If someone is set up for digital modes like FT8 then they have the equipment already. As such, it can be used on any band where there is SSB... HF or VHF.
An interesting feature is that FreeDV demodulator can automatically acquire signals with a frequency offset of up to ±200 Hz. This means that you don't have to be the exact same frequency as the other station. You can see how this might be of value in say a net on SSB where everyone is trying to get on the correct frequency.... and there's always one who is off a bit :o)
It's also worth mentioning that there are several FreeDV modes as well. 700D... This is for weak signal work on the HF bands and is claimed to work down as far as a signal to noise ratio of -2dB. The 700C version was introduced in 2017 and was replaced by the better 700D mode in 2018. 800XA... Similar to C4FM except over FM radio. Designed for VHF work. 1600... This is for a higher quality audio signal. 2020... 8 kHz of audio bandwidth is fitted in just 1.6 kHz of RF bandwidth. Delivers high quality audio when the signal are strong. Introduced in 2019.
Regular visitors to the blog will know that I try to promote more interest in the low-VHF part of the spectrum by having a dedicated page related to the new 40 MHz / 8 metre band. If I come across anything of interest that might be related to the band then I post it here on the blog and link to it from the 40 MHz page. The Clansman is an ex-British army radio that can operate on FM on the low VHF spectrum from 30 to 76 MHz. As such, it is one of the few radios available on the second hand market that can operate at 40 MHz, 50 MHz, 60 MHz or 70 MHz. Thanks to Steve EI5DD for his permission to post this guest post here....de EI7GL
The Clansman PRC-3512 is an intra-platoon level backpack VHF FM transceiver. The PRC 351 has 4 watt RF power output, and operates in the 30–75.975 MHz range with a possible 1840 channels spaced 25 kHz apart.
This radio is also capable of being mounted on a vehicle in conjunction with the TUAAM (Tuning Unit Automatic Antenna Matching). The PRC 352 is identical, with the addition of a 20 watt RF amplifier and can be used as a ground station also.
The Clansman RT-351 / VRC-351 Back-Pack 4 Watt portable VHF (FM) Radio was made by RACAL BCC Ltd. in England. The PRC-351 was designed to provide command communications at battalion and company level for dismounted troops. It was also used in vehicles by mounted troops. The PRC-351 replaced the older A41 and A42 British VHF radios.
The frequency Range 30 to 76.000 MHz in 25 Khz steps giving a total of 1841 programmable channels. The desired frequency is set by four knobs on the side of the radio which can be operated even while the operator is wearing Arctic mittens, or in the dark by counting clicks from the end-stops.
The World Radio communication Conference WRC-19 has just approved an allocation in the 50 MHz band for radio amateurs in Region 1 which includes Europe, Africa and the Middle East.
The entire region will now have an amateur secondary allocation of 50-52 MHz. This is usually granted on basis that secondary users do not cause interference to primary users of the band.
The exception is the Russian Federation, whose administration opted for only 50.080-50.280 MHz on a secondary basis.
This change should make a big difference in areas like Africa where only 11 countries have a primary allocation at present. The secondary allocation now opens the door for more activity from the continent.
According to a press release from the IARU, they state..."The exact manner in which the allocations will be implemented in Region 1 countries will be determined by each administration and may be either more generous or less, depending on national considerations."
So what does this mean??
While 26 countries in Region 1 currently have primary access to 50-54 MHz, the fact is that the vast majority of all 6-metre activity happens between 50 and 52 MHz. By having an official secondary allocation, radio amateurs in countries in Africa, Russia or the Middle East will now have a more valid reason for access to the band. This should result in more activity from those regions and this will be of interest to radio amateurs in western Europe.
It means that there is likely to be more DX related activity on the band which should encourage more activity. Every Summer, there will be multi-hop Sporadic-E from Europe to some of those potentially new countries on the band.
While the current predictions for the next sunspot cycle in a few years time aren't great, it should still result in good north-south paths. For stations in western Europe, this should result in openings to new countries in the Middle East and Africa.
Galway Radio Club in the west of Ireland have recently launched a new 48 page newsletter which covers some some recent club activities as well as a number of items which may be of interest to a wider audience.
These include... 1) An overview of how an amateur radio digital network was developed in the west of Ireland. 2) An overview of the experimental 5 MHz / 60m band. 3) Antennas for portable operation. 4) Understanding the Ionogram. 5) 160m top band operation. 6) G4HOL multi-band HF horizontal loop. 7) Operating the DVstick 30 - How to communicate on D-Star and DMR without a radio.
Monday the 11th of November 2019 was a pretty quiet day on 28 MHz for the most part. Other than a handful of European stations, the best DX to the south on FT8 was ZD7MY on St.Helena. The three exceptional signals however were WU1ITU, K0TPP and KC4QX in the USA.
On the lower bands like 18 MHz, 21 MHz or even 24 MHz, it's no big deal to hear an East-West signal outside of the Sporadic-E season. On 28 MHz and at the bottom of the sunspot cycle, it is.
When the solar flux is very low at the bottom of the sunspot cycle, propagation on 28 MHz via the F2 layer in the ionosphere is usually via North-South paths. As a result, hearing South Africa or South America from Europe on 28 MHz at the moment is nice but not exceptional. Hearing North America is unusual though.
I got just two FT8 decodes today from K0TPP in Missouri. He was 6,267 kms from here which is more than one F2 hop so perhaps there was some Sporadic-E helping to extend the path at one end or the other?
WU1ITU by contrast was much stronger and was at least +14dB here. That's a kind of level where a CW or SSB contact should be easily possible. It was a bit strange that these were the only two US stations that I heard.
KC4QX in Florida was heard much later at 18:43 UTC, about two hours after local sunset. Looking at the PSK Reporter website, it seems as if I was the only one in Europe in Europe to hear him.
Some of the my FT8 decodes are shown below. As you can see, WU1ITU was working Greece, France, Denmark and Spain.
Sunday the 10th of November 2019 was a pretty quiet day on 28 MHz with only one South African station being heard on FT8 here as well as a handful of Europeans.
I did a check of all the FT8 stations on 28 MHz from 9am to 9pm on the 10th of November and the map is shown above. I'm not sure if all the stations are shown but you can see very clearly where most of the activity is located.
It just highlights the fact that while there is plenty of activity from Europe, there is nobody active in most of Africa. This means that the 10-metre band may well be open from Europe to Africa at times but we can't tell.
An interesting day on 28 MHz with some mixed propagation on the band. There seems to have been some Sporadic-E between Ireland and Spain to the south. This then linked to what was probably F2 propagation from the latitude of Spain down to South Africa and Mauritius in the Indian Ocean.
On the 1st of November 2019, SDRplay announced the release of their new RSPdx model. This is a software defined radio intended for reception only and replaces their RSP2 and RSP2 PRO models.
It is described as follows..."The SDRplay RSPdx is a complete redesign of the popular RSP2 and RSP2pro multi-antenna receiver. It’s a wideband fullfeatured 14-bit SDR which covers the entire RF spectrum from 1kHz to 2GHz. Combined with the power of readily available SDR receiver software (including ‘SDRuno’ supplied by SDRplay) you can monitor up to 10MHz spectrum at a time. The RSPdx provides three software selectable antenna inputs, and an external clock input. All it needs is a computer and an antenna to provide excellent communications receiver functionality."
This particular model retails for about €200 / $200 which is twice the price of the RSP1a version.
SDRPlay seem to have a reputation for good SDR receivers at reasonable prices. The RSP1a looks like good value but I guess it depends on what you are looking for. The RSPdx has a metal enclosure with more sockets which might appeal to some.