Folks,
I have been working on voter design lately. I'm a ham, I don't make my
money working on radio, so I can both do this stuff slowly for fun. I
have constructed the S/N circuits in the LDG, and the original QST
article the LDG S/N section was based on... And about 1/2 dozen
variants of my own adding to and changing things in the design. The
LDG circuit works very well. The problem I found was a large disparity
in response between linked radios and the local receiver. Every radio
in the system throughout my tests has been standard narrowband
(+/-5kHz).
This work has not been to make a better voter than LDG or Doug Hall,
but just because I want to. I am currently building a valley type S/N
detector to measure the performance difference with that stye. The one
thing LDG really has going for them is that the S/N circuit connects
to an ADC and a microprocessor. The S/N detector is already clean, and
connecting my own designs to an ADC and microprocessor, I can see
where they likely make great improvements with software on top of the
hardware.
FWIW
73 DE N0MJS
On Jun 18, 2008, at 11:17 AM, skipp025 wrote:
> They type of audio used from the receivers can be just about
> any type as long as all of the receivers use the same audio.
Not really... depends on the specific voter circuit.
> Audio types that are acceptable are line level and speaker
> audio.
Any composite audio within the the level-range of the voter
circuit (varies with the specific voter circuit) and containing
the proper spectral components required by the voter circuit.
> Also, it does not matter if the audio is de-emphasized or
> not as long as all of the receivers are the same."
The audio doesn't have to be the same... but one would like to
say for most cases it's probably better. The de-emph yes or no
requirement is again dependent on the specific voter circuit
design and how it performs.
> It goes on to mention that audio response is the biggest
> challenge, try and get the audio response the same on all
> channels for best performance.
As a general rule of thumb probably so... but if you understand
the voter circuit... you can simply equalize the inputs where
required.
cheers,
skipp
--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206
