Equalization for non-coherent FSK burst modem

On 06/02/14 16:25, mite_learner wrote:
> I am also planning to do frequency hopping. Would that benefit me against
> multipath distortion?

Slow frequency hopping: no. It purpose it to reduce detectability
and mitigate narrowband channel fading.

Fast frequency hopping: yes, but AFAIK nobody bothers since they
use direct sequence spread spectrum has essentially the same
properties and is easy to implement.

OFDM uses more processing power in order to protect against channel
fades and inter-symbol interference.

<snip>
..
>>>
>>>For the block version you can use something like this in Matlab. What
>>we're doing here is basically solving the W-H Equation for the filter
>>taps.
>>>
>>>function zeq = cma(z,Neq)
>>>
>>>    [dummy,R]=corrmtx(z,Neq-1);
>>>    P=xcorr(z,z./abs(z),(Neq-1)/2);
>>>    W=R\P;W=W/sum(abs(W));
>>>    zeq = filter(W,1,z);
>>>
>>>end
>>>
>>>John
>>>
>>
>>Thanks for you reply.
>>
>>I am also planning to do frequency hopping. Would that benefit me
against
>>multipath distortion?
>>
>>ML	 
>
>Not much.   It really only helps if you would have otherwise picked a
>channel that was in a deep fade.  If the system is smart enough to not
>do that, and/or to move channels when it loses lock due to a fade,
>then FH isn't going to help to mitigate frequency-selective fading.
>If the signal bandwidth is wider than the channel coherence bandwidth,
>it'll help even less.
>
>FH is mostly an interference mitigation/suppression technique.
>
>
>Eric Jacobsen
>Anchor Hill Communications
>http://www.anchorhill.com
>

Hi Eric, thanks for your feedback. Yes, FH is mostly an interference
mitigation/suppression technique. I want to use it against multipath
interference as well at fast hopping rates :) 

ML	 

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>On 06/02/14 16:25, mite_learner wrote:
>> I am also planning to do frequency hopping. Would that benefit me
against
>> multipath distortion?
>
>Slow frequency hopping: no. It purpose it to reduce detectability
>and mitigate narrowband channel fading.
>
>Fast frequency hopping: yes, but AFAIK nobody bothers since they
>use direct sequence spread spectrum has essentially the same
>properties and is easy to implement.
>
>OFDM uses more processing power in order to protect against channel
>fades and inter-symbol interference.
>

Yes, it would be fast hopping around 2000-3000 hopes per second at a data
rate of 0.5Mbps to 1Mbps. Does this hopping rate would be of any benefit ?
I would be happy to go through the related literature/ research papers.

ML	 

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