DataRate definition?

Comments & issues
paynterf
Phidgetsian
Posts: 6
Joined: Thu May 22, 2008 8:15 pm

DataRate definition?

Postby paynterf » Sat Oct 08, 2011 9:37 pm

I'm a long-time (40+ years) EE and new Phidgets Spatial 0/0/3 user. I have been playing around with the very nice and complete sample code, and have been trying to wrap my old head around the definition for the DataRate parameter.

Apparently, the term DataRate, as defined by Phidgets, is actually more like DataInterval, i.e. the time in msec between samples rather than the frequency in Hz (i.e. 1/msec). Is that correct?

Frank

crob09

Re: DataRate definition?

Postby crob09 » Mon Oct 10, 2011 5:26 pm

Hi,

i was looking into that recently and found that your correct, it isn't measured in Hz.
From what I understand this makes things tricky when it comes to motion control software like Mach3.

User avatar
Patrick
Lead Developer
Posts: 3166
Joined: Mon Jun 20, 2005 8:46 am
Location: Canada
Contact:

Re: DataRate definition?

Postby Patrick » Tue Oct 11, 2011 12:10 pm

Yes, we decided to define datarate in ms rather then Hz because this lets users specify whole numbers - 1, 2, 4, 8, 16, 24, 32.... rather then having to use decimals - 1000, 500, 250, 125, 62.5, 41.6666666667, 31.25.....

-Patrick

paynterf
Phidgetsian
Posts: 6
Joined: Thu May 22, 2008 8:15 pm

Re: DataRate definition?

Postby paynterf » Tue Oct 11, 2011 12:39 pm

Patrick wrote:Yes, we decided to define datarate in ms rather then Hz because this lets users specify whole numbers - 1, 2, 4, 8, 16, 24, 32.... rather then having to use decimals - 1000, 500, 250, 125, 62.5, 41.6666666667, 31.25.....

-Patrick



OK, I can deal with that. Would have been nice to use 'DataIntervalMs' instead of 'DataRate' though ;-).

Frank

altenbach
Phidgetsian
Posts: 6
Joined: Wed Jul 20, 2011 6:17 pm
Contact:

Re: DataRate definition?

Postby altenbach » Wed Nov 16, 2011 6:14 pm

I agree that using the word "rate" is highly misleading, because it implies inverse seconds.

I am using a 1046 bridge and the manual actually use both:

Page 5: Supports specific data rates (from 1 to 125 samples/sec)
Page 7: You can use the slider to adjust the data rate from 8ms to 1000ms in increments of 8ms
Page 11: ms again.

Please don't call it a rate because it is not! This should definitely be changed!

Suggestion: "sampling period (ms)" or "sampling interval (ms)"
(see also http://en.wikipedia.org/wiki/Sampling_rate)

User avatar
Patrick
Lead Developer
Posts: 3166
Joined: Mon Jun 20, 2005 8:46 am
Location: Canada
Contact:

Re: DataRate definition?

Postby Patrick » Thu Nov 17, 2011 10:23 am

I admit that it's misleading. what would you think about changing dataRate to dataInterval? It's not really the sampling interval because samples are actually taken at a set higher rate and averaged together to get a specific data interval.

If we go this route, it would mean leaving in dataRate and marking it as deprecated, and then adding dataInterval and using it in documentation/examples, so as to not break peoples code.

-Patrick


Return to “General”

Who is online

Users browsing this forum: Google [Bot] and 2 guests