[Jack-Devel] Using USB sound card with Jack

[Chris Caudle]

On Tue, January 16, 2018 10:36 am, Benny Alexandar wrote:
> I want to test how zita-ajbridge behaves when there is a drift in clock.
> Any idea how to artificially create clock drift for testing purpose.

The clocks are going to naturally drift if they are not synchronized
externally.
In a lab environment I would use a frequency generator on a device that
could provide a S/PDIF stream for one of the devices to lock to, and
slowly vary the frequency.

Without lab equipment the best you could do would be to change the
temperature of the crystal that controls the sampling rate for one of the
devices.
Typically the equipment would be running around 30 degrees C, but the
components should be able to handle up to 50 degrees or 60 degrees C, and
down to about 0 degrees.  The quartz oscillators will vary in frequency
several PPM as the temperature swings.  Just be careful not to swing the
temperature too quickly, you could crack a solder joint, or potentially
cause the clock generator to lose sync if the frequency changes faster
than any PLL can track.
Assuming you don't have any lab rework equipment that can generate
controlled temperature air over a small area, your best bet might be a
hair dryer on low, and control the temperature by distance from the
blower.

-- 
Chris Caudle