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Old 16-01-2019, 13:10   #1
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SSB Frequency Selection

Hiya folks,

I am trying to get better at using my SSB. I have done some reading, and see that amongst other things frequency selection, time of day, season and distance all need to be factored into which frequency you select.

With that in mind I tried out this website VOACAP Online HF Predictions

And selected TX RX locations (Auckland and Fiji - about 1100NM) and it generated the following for "Best Freq"

Jan 2019 SSN = 4. Minimum Angle= 0.100 degrees
RF73JD RH82WI AZIMUTHS N. MI. KM
36.85 S 174.77 E - 17.64 S 177.88 E 8.95 187.51 1165.0 2157.4

The best operating frequencies (FREQ, FREQ2, FREQ3) by hour

UTC SDBW REL SNR MUFday FOT MUF HPF FREQ FREQ2 FREQ3

01 -96 (S9+) 100% 76 79% 16.6 20.8 24.9 18.1 21.1 14.1
02 -93 (S9+) 100% 83 51% 17.0 21.2 25.5 21.1 18.1 14.1
03 -92 (S9+) 99% 83 49% 17.0 21.0 25.0 21.1 18.1 14.1
04 -93 (S9+) 100% 78 78% 16.5 20.4 24.3 18.1 14.1 21.1
05 -93 (S9+) 100% 77 67% 15.7 19.4 23.0 18.1 14.1 10.1
06 -91 (S9+) 99% 78 52% 14.8 18.2 21.7 18.1 14.1 10.1
07 -93 (S9+) 98% 59 99% 13.7 17.1 20.5 7.1 14.1 5.4
08 -91 (S9+) 99% 60 97% 12.9 16.1 19.3 7.1 5.4 3.6
09 -89 (S9+) 99% 58 100% 12.3 15.4 18.5 5.4 3.6 7.1
10 -87 (S9+) 96% 53 100% 12.1 15.2 18.2 3.6 5.4 7.1
11 -87 (S9+) 96% 52 100% 11.8 14.9 17.6 3.6 5.4 7.1
12 -87 (S9+) 95% 52 100% 11.3 14.3 16.9 3.6 5.4 7.1
13 -87 (S9+) 93% 51 100% 10.6 13.5 15.9 3.6 5.4 7.1
14 -88 (S9+) 96% 56 98% 9.9 12.5 14.8 5.4 3.6 7.1
15 -89 (S9+) 96% 56 97% 9.3 11.4 14.8 5.4 3.6 7.1
16 -91 (S9+) 92% 51 100% 8.3 10.2 13.2 3.6 5.4 10.1
17 -95 (S9+) 94% 54 86% 8.3 10.1 13.1 5.4 3.6 10.1
18 -97 (S9+) 96% 57 100% 9.9 12.1 15.8 7.1 5.4 10.1
19 -97 (S9+) 99% 73 66% 11.8 15.2 17.7 14.1 7.1 5.4
20 -101 (S9+) 95% 73 41% 13.7 17.6 20.6 18.1 10.1 7.1
21 -96 (S9+) 100% 74 86% 13.5 17.4 20.3 14.1 18.1 10.1
22 -97 (S9+) 100% 73 84% 14.9 17.1 19.9 14.1 18.1 10.1
23 -98 (S9+) 100% 71 91% 16.0 18.4 21.5 14.1 18.1 21.1
24 -95 (S9+) 100% 78 67% 16.5 19.5 23.4 18.1 14.1 21.1


So if I read this correct, 10AM NZST (2200 UTC) the best frequency is 14.1Mhz?

However this website ( https://www.offshoreblue.com/communi...s/hf-intro.php )suggests 8Mhz is better for 1100nm.

Thoughts? Anyone used voacap website?

Cheers

Al
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Old 16-01-2019, 15:26   #2
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Re: SSB Frequency Selection

I see after a bit more research that VOACAP has a marine version for SSB:

VOACAP Online HF Predictions (Maritime)

Anyone want to try connecting on SSB sometime?
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Old 19-01-2019, 15:53   #3
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Re: SSB Frequency Selection

Al,
1) You're correct that time of day, season of year, communications distance, and especially current solar activity, all need to be factored into the choice of what freq to use...(as does the actual antennas used, and transmit power levels)

Quote:
Originally Posted by BigAl.NZ View Post
Hiya folks,

I am trying to get better at using my SSB. I have done some reading, and see that amongst other things frequency selection, time of day, season and distance all need to be factored into which frequency you select.
But...

2) But, the good news is:
a) In most cases, it's not too critical..
b) You don't need a computer, nor the internet, to make the choice...

What these two things mean is that as you garner more experience, you'll find using a computer model (like VOACAP or the Aus Propagation site, both wonderful, btw..) to be unnecessary....

FYI, it's been a few years since I took a look at VOACAP, and it's cool to see that they have a "maritime freq" version!!


3) For your proposed 1100nm path (NZ to Fiji path) in general, daytime comms would use the mid-HF bands (12mhz to 14mhz), but higher freqs for longer paths....nighttime comms along this path will be supported by mid to lower HF bands (evenings will still find 12mhz very usable, with 8mhz becoming the best choice later at night...)

So, for 10am local time (and with this being an almost N-S path, both ends will have similar solar exposure), yes 12mhz (or 14mhz ham) would be best!



4) As for all the numbers from the VOACAP charts....they may be cool for us egg-heads to ponder, but for most sailors they're a bit too much...

When I have recommended VOACAP to some, I usually recommend they either just use the "propagation wheel", or if they like some more info also look at the circuit reliability and signal strength charts ("REL & SDBW")....



5) Now, if you want an even easier way of looking at things....have a look at these videos....

Maritime HF Comms
https://www.youtube.com/playlist?list=PLnN6ygtZ3h2nPNdApNsZDo_Jk3NB_Bt1y

{please note the first two videos in this playlist deal almost exclusively with radiowave propagation and freq/channel choice, with LIVE real-world demonstrations on various freqs at various distances....and the last video in this playlist (that I just added last night) shows a quick, live, real-world demonstration of how easy-peasy it is to contact other stations without any "predictions" at all!}


Here are other playlists, which have some of the same videos, but have some specific / exclusive videos dealing with these specific topics....and these too are all done, LIVE as-it-happens, on a real offshore cruising boat, with no script, no pre-planning....just like everyone actually uses the radio!

HF-DSC Comms
https://www.youtube.com/playlist?list=PLnN6ygtZ3h2n3z5nlv-ga2zYuPozhUXZX

Offshore Weather
https://www.youtube.com/playlist?list=PLnN6ygtZ3h2mPZAx2vWzdjTJjHlChruyY

Icom M-802 Instruction Videos
https://www.youtube.com/playlist?list=PLnN6ygtZ3h2npivDjoFrC-8QKVyMb4tVr



6) Or, if you want to start with the very basics....the first way of looking at HF radiowave propagation is to use these simple rules-of-thumb:
The higher the sun = the higher the freq used
The lower the sun (below the horizon is lower) = the lower the freq used
The longer the distance = the higher the freq used
The shorter the distance = the lower the freq used

If you simply commit these basic rules to memory, and then watch the videos, I doubt you'll ever need to look at VOACAP again, except for fun!



I hope this helps...

Fair winds.

John


P.S. A quick look at the "offshoreblue" site shows it seems like a friendly / well-meaning rehash of what has been the "accepted" way of explaining HF radio to non-tech sailors for 45 - 50 years....
Not bad, but not very specific, and I think you'd get a much better understanding from just committing the above rules of thumb to memory, and watching the videos...


P.P.S.....as for your thoughts about a NZ to USA maritime SSB test, that sounds good to me....But, I'm tied up quite a bit...
But, FYI, late at night my time, and early evening your time, is a great time for me to work NZ from my dock here in Florida....perhaps 12.359mhz..
(done it before, as well as to Aus, etc...)
If you wish to go-for-it, I will try to reply to your other thread later tonight, and maybe I'd have the time??
Talk later....
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Old 19-01-2019, 17:40   #4
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Re: SSB Frequency Selection

Al, you might want to look at WSPR (Weak Signal Propagation Reporting). If you are an Amateur Radio Operator, you can transmit on the nearest ham band to your marine band you want to use. WSPR web site has map that shows the results of hundred of hams world wide and who can hear them.


Not sure if it will help but you will be able to see how the radio signals are moving about. N-S or E-W propagation. Short or long propagation.


I can't post links yet (still a newbie) so just google WSPR and give it a look.


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