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 s
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 p
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
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
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
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 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 shifts
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 an
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
lea
ost informative and certainly gives me more options.
>
> Bob
>
>
>
>
>
>>
>> From: Chris Albertson
>> To: Bob Stewart ; Discussion of precise time and frequency
>> measurement
>> Sent: Thursday, March 1
y 256.
This has been most informative and certainly gives me more options.
Bob
>
> From: Chris Albertson
>To: Bob Stewart ; Discussion of precise time and frequency
>measurement
>Sent: Thursday, March 13, 2014 5:42 PM
>Subject: Re: [time-
;
>
>
>
> >
> > From: Dennis Ferguson
> >To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
> >Cc: Hal Murray
> >Sent: Thursday, March 13, 2014 1:58 PM
> >Subject: Re: [time-nuts
Bob
>
> From: Dennis Ferguson
>To: Discussion of precise time and frequency measurement
>Cc: Hal Murray
>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
&g
On 12 Mar, 2014, at 23:08 , Hal Murray 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 good idea,
> but do
oating point operations in 8-bit unsigned characters on someone
else's control code on this PIC if I can get it to work properly my way.
Bob
>
> From: Jim Lux
>To: time-nuts@febo.com
>Sent: Thursday, March 13, 2014 7:57 AM
>Subject: Re: [ti
On 3/12/14 10:06 PM, Chris Albertson wrote:
On Wed, Mar 12, 2014 at 9:13 PM, Daniel Mendes 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
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 pe
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
On Wed, Mar 12, 2014 at 9:13 PM, Daniel Mendes 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 with a box car
f
m: Daniel Mendes
>To: Discussion of precise time and frequency measurement
>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
>e
ot, maybe there will be
a good gain value that will be convenient to code the exponential average.
Thanks for the help,
Bob
From: Hal Murray
To: Bob Stewart ; Discussion of precise time and frequency
measurement
Cc: hmur...@megapathdsl.net
Sent: Wednesday, Ma
scussion of precise time and frequency
>measurement
>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
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 t
s up!
Bob
>
> From: Magnus Danielson
>To: time-nuts@febo.com
>Sent: Wednesday, March 12, 2014 12:51 PM
>Subject: Re: [time-nuts] PLL Math Question
>
>
>Bob,
>
>
>
>Exponential averger takes much less memory. Consider this code:
>
>x_
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;
>> Wh
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 th
.com
>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
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 d
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 a
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