Packet Loss Functionality in Cyton and GUI
Hi, couple of questions about the packet loss functionality in Cyton and OpenBCI GUI.
At 250 sampling rate, how many packets are expected per second? Do lost packets mean the samples are permanently lost thus reducing the sample rate, or are the lost packets stored on the Cyton board and resent again after some time?
Comments
Hi Bit,
The Cyton is sending one radio packet per sample, so ~250 per second, 4 milliseconds between samples.
There is no saving or retransmitting. If the packet loss rate is just a few per second, it is not that significant. You can try this workaround to get your dongle closer to the mainboard: put the dongle on a usb extension cord and drape it over your monitor. That gets it off the tabletop and sometimes metallic surfaces can attenuate the radio signal.
Also be aware that other emitters of radio frequencies can cause interference, such as other wifi / bluetooth gear, extension cords, power supplies, LED lighting, conduits in walls, ceilings, nearby cell towers. If the extension cord tip does not help, try moving to a different location / room.
Regards, William
@wjcroft
In the 10 sec. period, instead of 2500 samples, it sometimes shows 2505 samples. What are these extra samples, are they acquired signals as well or for internal processing purposes only?
The sample rate is very close to 250.000 Hz, but may be slightly different. For example, off by a few hundredths or tenths of a Hz. This is constant and not a 'jitter' effect. Each mainboard may have a slightly different offset.