Re: LF: Digital modes comparison

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Presumably "QRSS very very slow" is better still, but here this issue is the time to get data through. Andy, I assume that you're saying WSPR or JT4A give the best "data per bandwidth per given time"?

73s
Roger G3XBM

On 30 July 2010 08:17, Andy Talbot <andy.g4jnt@googlemail.com> wrote:

Try WSPR at 6Hz bandwidth  or JT4A at less that 20Hz.   They are both MSFK constant envelope schemes.

 

Andy
www.g4jnt.com

2010/7/29 Stefan Schäfer <schaefer@iup.uni-heidelberg.de>

Andy, LF,

Which digital mode could be most suited for a band where one has just an antenna bandwidth of some Hz? You know what i mean... And what could be the "gain" compared to DFCW-600. Gain means here, how far(er) could it be detected, not how much more information can i transmit within the same time.

73, Stefan/DK7FC

PS: I see that e.g. JT65 needs abt 200 Hz, so this NOT suited!


Am 29.07.2010 23:07, schrieb Andy Talbot:

It would be very interesting to see those figures normalised to a constant data rate / bandwidth.  For example, PSK31 shown at -10dB is identical to PKK63 at -7dB - well it would be, its the same modulation, just faster.   Ie plot Bits/second/Hz vs. Eb/No, then stick the Shannon limit on the graph and see which lie nearest.

 

The fact that JT65 is at the top is probably because it sits at around 0.27 chars / second, or something like 1.2 B/s.  Although even after normalisation, it would no doubt still score well up.

 

Andy
www.g4jnt.com

On 29 July 2010 21:48, John Bruce McCreath <weazle@hurontel.on.ca> wrote:

Hello LFers,

I found this while web browsing....interesting reading and Mal's favourite mode isn't top dog.

http://kb2hsh.blogspot.com/2010/05/capabilities-of-weak-signal-digital.html

I was looking for sites having info about digital modes on 1,800 kHz. and lower frequencies.

73, J.B., VE3EAR

LowFER Beacon "EAR"
188.830 kHz. QRSS30
EN93dr

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