Automatic (no user-parameters) envelope/peak follower

On 30.7.15 17:30, Steve Pope wrote:
> Bob Masta <NoSpam@daqarta.com> wrote:
>
>> Dunno if anyone uses PDNs any more; they were parallel
>> chains of all-pass stages, with staggered TCs such that the
>> *difference* between the outputs of the two chains
>> approximated 90 degrees over the frequency range of
>> interest.   Lots of fun sorting and measuring Rs and Cs to
>> get the target tuning... ahh, the "good old days"!
>
> I believe there's a National datasheet on designing them ...
> if you use 1% resistors and 2% capacitors you're probably okay.
>
> Steve
>

It is standard material in ham radio books about SSB. There are
several different ways to skin this cat.

-- 

-TV

Tauno Voipio  <tauno.voipio@notused.fi.invalid> wrote:

>On 30.7.15 17:30, Steve Pope wrote:

>> Bob Masta <NoSpam@daqarta.com> wrote:

>>> Dunno if anyone uses PDNs any more; they were parallel
>>> chains of all-pass stages, with staggered TCs such that the
>>> *difference* between the outputs of the two chains
>>> approximated 90 degrees over the frequency range of
>>> interest.   Lots of fun sorting and measuring Rs and Cs to
>>> get the target tuning... ahh, the "good old days"!

>> I believe there's a National datasheet on designing them ...
>> if you use 1% resistors and 2% capacitors you're probably okay.

>It is standard material in ham radio books about SSB. There are
>several different ways to skin this cat.

Yes, the phase method for SSB used the same transfer functions ...
but those tended to be LC filters, and not active (op-amp)
RC filters.  

Lots of ways to do it.   

Steve

On 30.7.15 20:40, Steve Pope wrote:
> Tauno Voipio  <tauno.voipio@notused.fi.invalid> wrote:
>
>> On 30.7.15 17:30, Steve Pope wrote:
>
>>> Bob Masta <NoSpam@daqarta.com> wrote:
>
>>>> Dunno if anyone uses PDNs any more; they were parallel
>>>> chains of all-pass stages, with staggered TCs such that the
>>>> *difference* between the outputs of the two chains
>>>> approximated 90 degrees over the frequency range of
>>>> interest.   Lots of fun sorting and measuring Rs and Cs to
>>>> get the target tuning... ahh, the "good old days"!
>
>>> I believe there's a National datasheet on designing them ...
>>> if you use 1% resistors and 2% capacitors you're probably okay.
>
>> It is standard material in ham radio books about SSB. There are
>> several different ways to skin this cat.
>
> Yes, the phase method for SSB used the same transfer functions ...
> but those tended to be LC filters, and not active (op-amp)
> RC filters.
>
> Lots of ways to do it.
>
> Steve


Not quite - the networks have been RC, at least for my
entire ham career (since 1960). An example of the old times'
devices was the Barker & Williamson 2Q4, packed inside an octal
based tube format.

-- 

Tauno Voipio (OH2UG)