If no one else has mentioned it, there is a very complete treatment of
Synchros that was published by the guv'mint, United States Navy Bureau of
Ordnance OP1303, Synchros Description and Operation. My copy of the First
Rev is dated 1958.
73,
geo - n4ua
On Wed, Nov 21, 2018 at 11:00 PM Hans Hammarquist via TowerTalk <
towertalk@contesting.com> wrote:
> Jim,
>
> It is very easy to generate the V1, V2, V3 voltages if you want a receiver
> synchro to be set at a certain angles. You can even us a DC voltage for
> that. You just use the equations you show and replace the
> "cos(fline*2*pi*t)" with "1". It gets trickier to go the other way around
> as "C" not necessary is constant. You have to calculate that out of the
> know value of V1, V2, and V3.
>
> I'm sure there is an easy way to do that but it become a "little" easier
> if you first make a Scott-T transformation (see Wikipedia "Scott-T
> transformer) because your equations will be easier to reverse and
> calculation of "C" easier too.
>
> C=(Vr^2*Vi^2)^1/2
>
> theta=arctan(Vr/Vi)
>
> When you finally are ready to implement your algorithm you have to make a
> synchronous rectification somewhere to get the value and the sign. You can
> do it before the A/D converter with a synchronous rectifier or probably
> with the software. (I would love to see a software that can do this. It
> should be possible.)
>
> Regarding the precision there are a few things to keep in mind. It is very
> important that the output voltages are kept good. That means that the
> attenuation in the signal lines have to be the same. If one of them is off
> you will experience an error in your read-out. Therefore, the control cable
> has to be of a good quality with even wire thickness and resistance along
> the cable. You have to use five wires, two for th excitation and three for
> the return signals. You can not use a common wire for excitation and
> signals at that would introduce errors.
>
> There are commercial IC-s around that will do this. I know one application
> where a virtual sychro is virtually rotated and the "C" is adjusted until
> the V'1, V'2 and V'3 are as equal to the received signal as possible
> (leaving room for variations in an unbalanced attenuation). You notice that
> adjustment process as the output signal varies untill the readout stops at
> the correct value.
>
> Who will be the first to make a Ham-type software to decode the sychro
> signal? I will be the first in line to get it.
>
> 73 de,
>
> Hans - N2JFS
>
>
> -----Original Message-----
> From: jimlux <jimlux@earthlink.net>
> To: towertalk <towertalk@contesting.com>
> Sent: Mon, Nov 19, 2018 10:14 am
> Subject: Re: [TowerTalk] Fwd: Telrex rotator
>
> On 11/19/18 6:31 AM, Hans Hammarquist via TowerTalk wrote:
> > Hi Martin,
> >
> > Decoding the signals from a selsych is a "little" complex as it require
> you to do A/D convert all three signals at the same time, then do the
> mathematical quirk to calculate the angle out of that. Not impossible.
>
> Assuming you don't need microdegree accuracy, and 1 degree is good
> enough, you don't actually need "precisely synchronized" sampling,
> ...
>
> The voltage on each winding is:
> V1 = C* cos(theta)*cos(fline*2*pi*t)
> V2 = C* cos(theta+2pi/3) * cos(fline*2*pi*t)
> V3 = C* cos(theta+4pi/3) * cos(fline*2*pi*t)
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|