ThingMagic Mercury API v1.23.0 - Manual (Page 127)

Optimizing Gen2 settings
Performance Tuning 127
Optimizing Gen2 settings
If the previous information on Gen2 settings is new to you, the task of optimizing all these
settings together will likely appear daunting to you at this point. Fortunately, we have
created a step-by-step procedure for achieving the desired results.
1. Set the reader up to achieve the maximum read distance possible (Tari=6.25 usec,
BLF=250kHz, M=8) at the anticipated transmit level (usually the highest allowed by
regulations unless the read-field size must be limited). Place tags at the maximum
read distance required for your application and ensure that all tags are read reliably.
2. Setup your “Q” and session value for the expected tag population (2^Q should be
greater than 1.5 times the number of tags). If the number of tags will vary widely, use
the ThingMagic “automatic” setting.
3. Set the session value. The maximum-distance BLF and M settings will read around
100 tags per second, so the session should be set to “0” if you anticipate up to 50
tags, “1” for up to 200 tags, and “2” (or “3”) if you anticipate there being more tags in
the field.
4. Now determine if these settings meet your requirements for tag read rate (or the
ability to read a tag moving through the field). If the read rate (or single-tag read time)
is too slow, start decreasing the “M” value (keeping the BLF at 250 kHz) until the
desired read rate is achieved. (If FM0 and 250 kHz is insufficient, try FM0 and 640
kHz.) Now check your system performance at the required distance again to make
sure your tags can still be read reliably. If it is still OK, keep these settings. If not, you
will have to decide on the best compromise values for M and BLF that balance read-
distance with read-rate.
5. If the application calls for it, add more readers with the same settings. Check the
performance of the first reader while the other readers are operating. If it has not
changed, leave its settings alone. If its performance has decreased, then reader-to-
reader interference is probably occurring. First increase the Tari on all readers to see
if that helps (this change will impact the other performance factors least.) If that does
not work, try decreasing the BLF and increasing the M value to see if that eliminates
the problem. If so, you must select the BLF and M values which give you an
acceptable level of reduced reader-to-reader interference, read rate, and read
distance.
6. If your application requires a few tags to respond repeatedly, use session=”0” and
leave the target=”A” setting alone. If there are enough tags in the field to require
using session “1” or “2”, but you need the tags to re-respond more rapidly than the
session timers allow, use the target=”A then B” setting.
At this point, your Gen2 settings will be optimized and your system will be operating at
peak performance. If you are still experiencing difficulties, additional resources are
available from ThingMagic.