What issues are involved with possibly thousands of ID codes on a single frequency?
It is important for the researcher to realize that one receiver can only detect one ID code at a time. If two codes overlap at one receiver site then neither code will be detected. Because of randomization of Delay Time (the silence between transmissions), the next time these two tags transmit, the chances are that they will not collide and both will be detected. The choice of the average Delay is important because it will influence how many tags can be detected in the same location. The average time between detections depends on the number of transmitters present and transmitter Delay Time. VEMCO provides an on-line Collision Calculator which calculates collision statistics including average time between detections. Some representative results for A69-1303 (R64k SYNC = 320) coding are shown in the table below. For site residency studies where fish may be present for many days, the average delay can be multiple minutes or longer. However, for fast moving fish migrating through river sy
