[pskmail] Re: pskmail on other mode
- From: Adrian Engele <aa5uk@xxxxxxxxx>
- To: pskmail@xxxxxxxxxxxxx
- Date: Thu, 27 Aug 2009 15:10:37 -0700 (PDT)
Hi John,
Just reading all the PSKMail BB messages and just saw yours. Interesting
analysis for sure.
I was wondering if you had seen the following analysis of the various modes on
the flidigi site: http://www.w1hkj.com/FldigiHelp/Modes/index.htm
Just thought I would pass it along in case you haven't.
73,
Adrian
AA5UK
Chicago, IL
________________________________
From: John Douyere <vk2eta@xxxxxxxxx>
To: pskmail@xxxxxxxxxxxxx
Sent: Thursday, August 27, 2009 4:57:57 PM
Subject: [pskmail] Re: pskmail on other mode
Hi Greg,
Here in VK we have long distances and not many people in between, so mobile
coverage is quickly fading off when we get away from the cities.
So I have done a number of experiments in HF NVIS and VHF and although it is
not "PSKmail" per say it works quite well with other modes (some better than
others).
Here is a summary of my experience:
- in VHF and UHF I did some comparisons between SSB and FM. Although FM needs a
higher signal to noise ratio than SSB to work for voice, some digital modes
give almost the same performance in SSB and FM: I have tried successfully THOR,
MFSK but not DominoEX for a strange reason.
One issue with SSB on VHF and worse in UHF is that for staying within the
acquisition range of the server (typically 20 to 40Hz), the accuracy of the VFO
would need to be much higher than what is available currently. My FT857 and 817
give at best +/-1PPM but at 145MHZ I would need 0.27PPM of stability.
So most modes like PSK, and the slow MFSK ones are difficult to tune using SSB
at VHF as it is easy to be 100 or 150Hz out despite having the right dial
frequency.
This is where FM wins, because tuning is not so important. So what you loose in
sensitivity (a little only with the right modes), you gain in ease of tuning.
The only modes I had success with on VHF/SSB was THOR because of it's tolerance
to mis-tuning.
Using FM, I could barely hear the signal in the noise (no squelch), but the
decoding was good. In only one case did THOR perform better on SSB than on FM.
- In HF, as Rein (or Per I am not sure) has confirmed by tests, some other
modes are much more sensitive than PSK250 or 125. They also survive much better
the multipath distorsion of NVIS and lightning strikes noise in the low
frequencies (typically 80 and 40M).
My best experiences have been using MFSK and THOR. I had poor results with
DominoEX which is strange since it is a close cousin of THOR. I also had poor
results with the MT modes because I believe of the interaction between fldigi
and PSKMail (the control characters are not consistently passed through in my
experience).
I haven't tried Olivia much but it should work also.
So my best vote so far based on my experience: THOR8 for robustness (but it is
slow), otherwise THOR22 is a good compromise. For speed MFSK64 is really good
but 1K bandwidth, and MFSK16 or 22 a good compromise between robustness and
bandwidth.
In my experience in marginal conditions THOR22 and MFSK32 will beat PSK hands
down. You can try one of these two with the current settings in the servers.
Note that if you want to use the slower modes like THOR8 or MFSK16 some
adjustments to the timings of the server are necessary. In fact I have compiled
a series of small changes that are required for the server to accept these slow
modes.
I can now successfully have a position report or a connected session with
THOR8. I get a very very robust link. I can send you the code if you want to
experiment.
Sorry for the long response, but I find that subject interesting.
Hope this helps,
Regards,
John (VK2ETA)
On Fri, Aug 28, 2009 at 5:11 AM, Greg <kb1ncj@xxxxxxxxx> wrote:
Would pskmail function on MT63 2k on vhf, uhf? It wouldn't be "psk"mail, but
was wanting to experiment... -Greg
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