[Moon-Net] Green Heron vs Alfa Spid Controller
on4aoi_pda at skynet.be
Wed Apr 7 08:21:52 CEST 2021
I had both RAS/HR(sold) and BIGRAS/HR with MD01 and MD02 in my case the
RAS/HR with MD01 or MD02 has always been correct.
But like I wrote in my other Subject the BIGRAS/HR was wrong since day1. I
swapped MD01 with MD02 and cables (same type and length) from RAS to BIGRAS
And back again , My RAS remained perfect but BIGRAS was always wrong. I
suspect that to get a higher precision the BIGRAS sends more pulses that get
lost or can't be handled.
From: Moon-net <moon-net-bounces at mailman.pe1itr.com> On Behalf Of Bob Atkins
Sent: Wednesday, April 7, 2021 5:56 AM
To: moon-net at mailman.pe1itr.com; Leslie L <llistwa at gmail.com>
Subject: Re: [Moon-Net] Green Heron vs Alfa Spid Controller
My SPID RAS HR and MD-02 controller really doesn't lose pulses. I
recalibrate from time to time (maybe once month), but it's rarely for than
0.2 degrees off. I would think the regular RAS pulses would be even easier
to count because they are less frequent and they are simple pulses (magnet
and reed switch), not requiring quadrature decoding.
Have you read this? https://bobatkins.com/radio/spid_ras_hr.html and
Pulse counting depends on a couple of things. One is noise. If there's noise
on the lines that bring the signal in from the sensor, then you can get bad
counts. That leads to the benefit of line drivers at the sensor and good
filtering at the controller end of things.
Never used a Green Heron, don't know what's in the box. The SPID hardware is
also something of a mystery as they don't publish controller schematics as
far as I know. Their software (PASCAL) is open source I think.
I'd stick a fast scope on the sensor line and take a see what the pulses
look like. Maybe you will see noise which requires filtering. Maybe the
shape of the pulses will be distorted, in which case you might want some
signal conditioning (Schmitt trigger, buffer, level shifter etc.). I don't
know how fussy the SPID controller is, but it can't object to clean square
waves (can it?).
Any pulse counting system can (and probably will) eventually glitch and lose
proper count, but it shouldn't happen often.
From: Moon-net <moon-net-bounces at mailman.pe1itr.com
<mailto:moon-net-bounces at mailman.pe1itr.com> > on behalf of Leslie L via
Moon-net <moon-net at mailman.pe1itr.com <mailto:moon-net at mailman.pe1itr.com> >
Sent: Monday, April 5, 2021 9:10 AM
To: moon-net at mailman.pe1itr.com <mailto:moon-net at mailman.pe1itr.com>
<moon-net at mailman.pe1itr.com <mailto:moon-net at mailman.pe1itr.com> >
Subject: [Moon-Net] Green Heron vs Alfa Spid Controller
Many of you swear by the Green Heron RT-21AZ controller over the standard
Alfa Spid Controller when using the SPID RAS rotors in its ability not to
lose pulses and maintain its accuracy. I am wondering if someone can
explain why the Green Heron is more accurate. Do they condition the
pulses? They are both dealing with the inherent limitations of using a
simple reed switch and magnet as the encoder on the rotor itself. What is
the secret sauce that makes the Green Heron a better controller in this
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