Hi Bob,
On 12/03/14 19:26, Bob Stewart wrote:
Hi Magnus,
Thanks very much for this response! It will be very easy to add the
exponential averager to my code and do a comparison to the moving average. I
have no experience with PI/PID. I'll have to look over the literature I have
on them
On 12/03/14 20:25, Hal Murray wrote:
mag...@rubidium.dyndns.org said:
Exponential averger takes much less memory. Consider this code:
x_avg = x_avg + (x - x_avg) * a_avg;
Where a_avg is the time-constant control parameter.
Also note that if a_avg is a power of 2, you can do it all with
Hi Bob,
On 12/03/14 23:16, Bob Stewart wrote:
x_avg = x_avg + (x - x_avg) * a_avg;
Hi again Magnus,
In fact, I just post-processed some data using that formula in perl. It looks
great, and will indeed save me code and memory space. And, it can be a user
variable, rather than hard-coded.
On 13/03/14 07:35, Daniel Mendes wrote:
Em 13/03/2014 01:35, Bob Stewart escreveu:
Hi Daniel,
re: FIR vs IIR
I'm not a DSP professional, though I do have an old Smiths, and I've
read some of it. So, could you give me some idea what the FIR vs IIR
question means on a practical level for this
On 13/03/14 13:57, Jim Lux wrote:
On 3/12/14 10:06 PM, Chris Albertson wrote:
On Wed, Mar 12, 2014 at 9:13 PM, Daniel Mendes dmend...@gmail.com
wrote:
This is a FIR x IIR question...
moving average = FIR filter with all N coeficients equalling 1/N
exponential average = using a simple rule to
On 14/03/14 00:39, Bob Camp wrote:
Hi
Either grab a math pack (there are several for the PIC) or go to C.
Timing at the Time Nuts level is about precision. We need *lots* of digits past
the binary point :)
Indeed. Throwing bits at the problems is relatively cheap today.
Besides, you don't
Bob,
Just been reading along, enjoying the conversation...
I've written a lot of hand coded assembly. Some of it very similar to
what you are doing here now. (Although, a different processor family)
I really didn't want to switch to C for anything, since code generated
is 'bloated'.
That being
Em 13/03/2014 01:35, Bob Stewart escreveu:
Hi Daniel,
re: FIR vs IIR
I'm not a DSP professional, though I do have an old Smiths, and I've read some
of it. So, could you give me some idea what the FIR vs IIR question means on a
practical level for this application? I can see that the MA is
albertson.ch...@gmail.com said:
We have to define best. I'd define it as the error integrated over time
is minimum. I think PiD gets you that and it is also easy to program and
uses very little memory. Just three values (1) the error, (2) the total of
all errors you've seen (in a perfect
On 3/12/14 10:06 PM, Chris Albertson wrote:
On Wed, Mar 12, 2014 at 9:13 PM, Daniel Mendes dmend...@gmail.com wrote:
This is a FIR x IIR question...
moving average = FIR filter with all N coeficients equalling 1/N
exponential average = using a simple rule to make an IIR filter
Isn't his
else's control code on this PIC if I can get it to work properly my way.
Bob
From: Jim Lux jim...@earthlink.net
To: time-nuts@febo.com
Sent: Thursday, March 13, 2014 7:57 AM
Subject: Re: [time-nuts] PLL Math Question
On 3/12/14 10:06 PM, Chris Albertson
On 12 Mar, 2014, at 23:08 , Hal Murray hmur...@megapathdsl.net wrote:
b...@evoria.net said:
In the moving averages I'm doing, I'm saving the last bit to be shifted out
and if it's a 1 (i.e. 0.5) I increase the result by 1.
That's just rounding up at an important place. It's probably a
From: Dennis Ferguson dennis.c.fergu...@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Cc: Hal Murray hmur...@megapathdsl.net
Sent: Thursday, March 13, 2014 1:58 PM
Subject: Re: [time-nuts] PLL Math Question
Note that you can't do fixed-point computations
...@gmail.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Cc: Hal Murray hmur...@megapathdsl.net
Sent: Thursday, March 13, 2014 1:58 PM
Subject: Re: [time-nuts] PLL Math Question
Note that you can't do fixed-point computations exactly the same way
you would
PM
Subject: Re: [time-nuts] PLL Math Question
You don't really shift so much as just change the way you think about it.
The way to think about it is not that you have 16th but that you have the
binary point force places over. It works just like a decimal point. If
you multiply two
From: Dennis Ferguson dennis.c.fergu...@gmail.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Cc: Hal Murray hmur...@megapathdsl.net
Sent: Thursday, March 13, 2014 1:58 PM
Subject: Re: [time-nuts] PLL Math Question
Note that you can't do
li...@rtty.us said:
Timing at the Time Nuts level is about precision.
What's the term for a time-nut that's trying to be not-very-nutty?
--
b...@evoria.net said:
includes a 10-bit PWM dithered to 14 bits
When you get it all working, that's going to be one of the weak links, at
Now that I've got the TIC going, I'm working on the PLL math for my GPSDO. My
question is about moving averages. I've put in a moving average for the TIC.
From that, I've calculated the slope, and have put a moving average on the
slope to settle it down. I think this boils down to a moving
Bob,
On 12/03/14 18:24, Bob Stewart wrote:
Now that I've got the TIC going, I'm working on the PLL math
for my GPSDO. My question is about moving averages. I've
put in a moving average for the TIC. From that, I've
calculated the slope, and have put a moving average on the
slope to settle it
Sent: Wednesday, March 12, 2014 12:51 PM
Subject: Re: [time-nuts] PLL Math Question
Bob,
On 12/03/14 18:24, Bob Stewart wrote:
Now that I've got the TIC going, I'm working on the PLL math
for my GPSDO. My question is about moving averages. I've
put in a moving average for the TIC. From
mag...@rubidium.dyndns.org said:
Exponential averger takes much less memory. Consider this code:
x_avg = x_avg + (x - x_avg) * a_avg;
Where a_avg is the time-constant control parameter.
Also note that if a_avg is a power of 2, you can do it all with shifts rather
than multiplies.
Note that
@febo.com
Cc: hmur...@megapathdsl.net
Sent: Wednesday, March 12, 2014 2:25 PM
Subject: Re: [time-nuts] PLL Math Question
mag...@rubidium.dyndns.org said:
Exponential averger takes much less memory. Consider this code:
x_avg = x_avg + (x - x_avg) * a_avg;
Where a_avg is the time-constant control
From: Magnus Danielson mag...@rubidium.dyndns.org
To: time-nuts@febo.com
Sent: Wednesday, March 12, 2014 12:51 PM
Subject: Re: [time-nuts] PLL Math Question
Bob,
snip
Exponential averger takes much less memory. Consider this code:
x_avg = x_avg + (x - x_avg) * a_avg
b...@evoria.net said:
In the moving averages I'm doing, I'm saving the last bit to be shifted out
and if it's a 1 (i.e. 0.5) I increase the result by 1.
That's just rounding up at an important place. It's probably a good idea,
but doesn't cover the area I was trying to point out. Let me
and frequency
measurement time-nuts@febo.com
Cc: hmur...@megapathdsl.net
Sent: Wednesday, March 12, 2014 10:08 PM
Subject: Re: [time-nuts] PLL Math Question
b...@evoria.net said:
In the moving averages I'm doing, I'm saving the last bit to be shifted out
and if it's a 1 (i.e. 0.5) I increase
, March 12, 2014 10:08 PM
Subject: Re: [time-nuts] PLL Math Question
b...@evoria.net said:
In the moving averages I'm doing, I'm saving the last bit to be shifted out
and if it's a 1 (i.e. 0.5) I increase the result by 1.
That's just rounding up at an important place. It's probably a good idea
dmend...@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Wednesday, March 12, 2014 11:13 PM
Subject: Re: [time-nuts] PLL Math Question
This is a FIR x IIR question...
moving average = FIR filter with all N coeficients equalling 1/N
exponential average
On Wed, Mar 12, 2014 at 9:13 PM, Daniel Mendes dmend...@gmail.com wrote:
This is a FIR x IIR question...
moving average = FIR filter with all N coeficients equalling 1/N
exponential average = using a simple rule to make an IIR filter
Isn't his moving average just a convolution of the data
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