Frequency hopping within a single band - 70MHz (4 metre band)

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GM4FVM
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Frequency hopping within a single band - 70MHz (4 metre band)

One of the issues about the 70MHz band is that only a few countries authorise it, but more to the point, almost every country has a different allocation. This is in some ways similar to the early development of the lower frequency MF bands.

The 4 metre band dial frequency in use for WSPR is currently 70.091. This is fine for transmitting in the UK or Italy, but it falls outside the allocations in Ireland, Germany and Spain, for example. So, to date, stations in those countries have been restricted to listening, even if they had licences to transmit on other parts of the band. With the patchwork quilt of allocations, there is no single frequency which allows all of us to transmit.

I was pleased to see Juan Carlos, EA4ETR, on the band recently. As the Spanish allocation is 70.150 to 70.200, Juan Carlos was using the frequency of 70.153, and several stations were listening for him there. For me though, I could only operate there if I left behind 70.091, which is where most other stations operate.

So, using WSPR 2.21 I set up "frequency hopping" with the usual 4m settings, but 70.153 in the "other" field. Tests showed that with frequency hopping turned on, I could operate effectively on both frequencies within the one band. The display on WSPR shows "4" or "oth" as it hops between the two. I have already worked two stations alternately on both frequencies. The CAT function worked 100% OK, and the WSPRnet activity screen showed either frequency in use (though of course not in real time!).

Setting it up is simple provided you are using CAT control. Just select the "other" band, enter 70.153000 as the dial frequency, and then pick a tx frequency by double clicking on the waterfall display. The red line will then show your tx frequency for the "other" band. Then it is just a matter of selecting your tx ratio, clicking the "4m" and "other" bands in the frequency hopping tab and the main WSPR screen. WSPR 2.21 does the rest, switching between the frequencies within the 4m band.

The slight snag to all this is that it introduces a second frequency in use on 4m and possibly opens the door to missing contacts by being on the wrong one. That is worth the risk for me as I was quickly spotted by Juan Carlos at 1691km - thanks for that:-

2014-07-01 16:36 GM4FVM 70.154463 -15 2 IO85wu +40 10.000 EA4ETR IN80cq 1691 1051
2014-07-01 16:30 GM4FVM 70.154464 -6 1 IO85wu +40 10.000 EA4ETR IN80cq 1691 1051

So there is a way to work on two frequencies in one band, though I would not recommend it unless you have to, as in the case of 4m. It is best to stick to the recommended frequencies if we can otherwise we will all lose each other.

Also, stations like Juan Carlos' could also use hopping by using the same hopping arrangement and keeping the tx ratio at "zero". Thus he could monitor 70.091 while tx/rx on 70.151. Although it is different time segments, it should work better than 70.153 alone.

I doubt if in-band 4m frequency hopping was in the minds of those who helpfully created frequency hopping, but I am glad they did make this possible.

Jim
GM4FVM