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From: Vladimir Vassilevsky on 28 Jan 2010 11:50


Rafael Deliano wrote:


>
> Delay&Multiply isn?t optimal for radio/noise but is simple to implement.

Delay Multiply is a kind of discriminator. As such, if properly
implemented, its SNR performance is no different from other
discriminators (atan2, dfi/dt, frequency counter, etc.)

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
From: Vladimir Vassilevsky on 28 Jan 2010 11:53


Mark wrote:

>>I didn't answer before because I have no particular expertise in this
>>field. If I were attacking the problem, my early thought would be to use
>>a pair of filters tuned (one each) to the mark and space frequencies,
>>and compare their outputs. I'd avoid the temptation to make them too
>>selective, because that slows down their responses.
>>
> this method actually enjoys an advantage, if the mark/spacing is wide
> compared to the baud rate, then the two filter BWs can be reduced such
> that the system will reject noise and interference BETWEEN the mark
> and space. THe PLL and other FM demod approaches do not share that
> advantage.

The PLL and other FM demod approaches do have that advantage if
implemented properly.

VLV
From: Jerry Avins on 28 Jan 2010 21:00
Vladimir Vassilevsky wrote:
>
>
> Rafael Deliano wrote:
>
>
>>
>> Delay&Multiply isn?t optimal for radio/noise but is simple to implement.
>
> Delay Multiply is a kind of discriminator. As such, if properly
> implemented, its SNR performance is no different from other
> discriminators (atan2, dfi/dt, frequency counter, etc.)

I remember delay-and multiply discriminator, but I don't have a handle
on the best delay.

Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
From: Vladimir Vassilevsky on 28 Jan 2010 21:35


Jerry Avins wrote:
> Vladimir Vassilevsky wrote:
>
>>
>>
>> Rafael Deliano wrote:
>>
>>
>>>
>>> Delay&Multiply isn?t optimal for radio/noise but is simple to implement.
>>
>>
>> Delay Multiply is a kind of discriminator. As such, if properly
>> implemented, its SNR performance is no different from other
>> discriminators (atan2, dfi/dt, frequency counter, etc.)
>
>
> I remember delay-and multiply discriminator, but I don't have a handle
> on the best delay.

1/2
T = ----------------
Fmark - Fspace


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
From: Jerry Avins on 28 Jan 2010 21:42
Vladimir Vassilevsky wrote:
>
>
> Jerry Avins wrote:
>> Vladimir Vassilevsky wrote:
>>
>>>
>>>
>>> Rafael Deliano wrote:
>>>
>>>
>>>>
>>>> Delay&Multiply isn?t optimal for radio/noise but is simple to
>>>> implement.
>>>
>>>
>>> Delay Multiply is a kind of discriminator. As such, if properly
>>> implemented, its SNR performance is no different from other
>>> discriminators (atan2, dfi/dt, frequency counter, etc.)
>>
>>
>> I remember delay-and multiply discriminator, but I don't have a handle
>> on the best delay.
>
> 1/2
> T = ----------------
> Fmark - Fspace

Thanks.
I remember demodulating NBFM that way, but I didn't recall T/deviation.


Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
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