Hello Giles,

I did the time measurments for both microcontroler acquisition and bluetooth
comunication to the PC.

For the BT transmission duration, I've noticed that the more lines I
extracted, the more bytes I had to transmit, so the transmision time
increased as expected.

For the microcontroler acquisition duration, I was expecting also an
increase with the number of lines taken, since more lines needed to be
acquired. Instead I get more or less a constant value arround 400ms, for
evry camera configuration, with a huje jitter value (standard deviation of
the captures is arround 100-150ms).

I went to po3030k.h where it is written the frame rates for some camera
configurations. Mine is not there (  GRAY (1-8)x480 with zoom of 1,2,4,8  )
but I was expecting it be arround the maximum frame rate (8 fps). Instead
I'm getting arround 2 fps with huje jitter.

I want to take out the Jitter of the captures and obtain the maximum frame
rate that the configurations I am using allow. What should be the durations
that I should obtain for microcontroler acquisition with my camera


2011/7/21 Gilles Caprari <g.capr...@ieee.org>

> **
> Dear Duarte,
> this example might be an inspiration
> http://www.gctronic.com/doc/index.php/E-Puck#Still_images
> usign the zoom basically skips pixels and lines and takes only the one
> usefull. Not sure if you mean acquisition from the microcontroller or also
> on the PC via bluetooth (BT). In that later case, most of the time required
> by the BT communication.
> regards,
> Gilles
> On 20:59, Duarte Dias wrote:
> Hi,
>  I am using  the e-puck 1176 (VGA camera 480x640 - rotated camera).
>  I am capturing some full (480 pixels) horizontal lines (1 to 8 lines)
> applying the zoom factor of 1, 2, 4 and 8 (on the x component which in this
> epuck camera is the vertical component).
>  I assume that if I am capturing 4 horizontal lines with zoom 2 its the
> same of capturing 8 lines with zoom 1 (and so one). The zoom just does the
> line averaging within groups of 2 lines.
>  When I capture the images I am using a timer (TIMER1) to quantify the
> capture duration.
>  After my experiments from capturing 1 - 8 lines with zoom 1,2,4,8 I have
> concluded that the capture time is approximatly constant (between 350 and
> 450), no matter the number of lines we take and the zoom we do.
>  I have also witnessed a large Jitter between frame captures (the standard
> deviation of the frame capture times is arround 150ms!).
>  I was expecting a rise of time when I extracted more lines and no Jitter
> should exist. Could someone tell me what I could be the cause of this
> behaviour (expecially the Jitter behaviour).
>  Regards,
> Duarte Dias
> --
> ------------------------
> Dr. Gilles Caprari
> GCtronic Sagl, Electronics & Mechatronics
> web: www.gctronic.com E-mail: g.capr...@ieee.org
> Post: Via Cassarinetta 2, CH-6900 Lugano, Switzerland
> Tel: +41 91 630 2149 Fax: +41 43 556 8006
> Mobile: +41 78 601 1113 skype: gillescaprari
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