EDIT: The default they ship on isn’t 20%, just whatever the hardware default is which appears quite high if not equivalent to 100%?
If you have an ACR1552u and want to tinker with the RF power level and RF off interval, see above script. pyscard is a required dependency. Mind the bed video.
If changing RF off interval (–pulse), you will have to unplug/replug the reader for the changes to take effect.
acr1552u_rf_config.py --power 100 --pulse 0 # full power, field always on
acr1552u_rf_config.py --power 40 --pulse 500 # 40%, pulse off 500 ms/poll
acr1552u_rf_config.py --pulse 250 # just set pulse, leave power
acr1552u_rf_config.py # read current settings
Will this improve the readers actual performance interfacing with your implants? I’ve no idea… I’ve been running all my 1552u’s like this from day 1 and I don’t think it’s made anything worse. It certainly helps showing off blinkies (though, I guess they don’t really blink if the field is continuous)… Only downside I’ve noticed, cards get hot if they sit on the reader for a long time.
If you’ve been using a 1552u on default settings for awhile, I’d be curious to hear if you feel it makes a difference.
Nice script. One thing worth keeping in mind when tuning these two settings together: power and pulse interval trade off against each other in ways that aren’t obvious from the numbers.
The --pulse value is the RF-off time between polls, so it sets the worst-case latency before a tag in the field gets seen. A 500 ms off-interval means a tag swiped quickly through the field can be missed entirely even at full power, because it was in range only during the off window. If you’re finding reads unreliable after turning power down, try shortening the pulse before pushing power back up - it’s often a timing problem being misread as a range problem.
Going the other way, the reason to run reduced power with a longer off-interval is heat and average field, not peak field. Duty cycle scales the average, so 40% power with a 500 ms gap is dramatically less energy into the antenna than 100% continuous, while the peak field during the on-phase is still whatever the power setting gives. If you’re characterising range, measure with pulse 0 so you’re not accidentally measuring your poll timing instead of your field.
Also worth noting that these readers won’t be linear in “percent”. The number is almost certainly a driver/attenuator setting, not calibrated field strength, so 50% is not half the field and definitely not half the read range - range falls off very steeply with distance for a near-field coil. If you want real comparisons between settings, a small pickup coil and a scope on the antenna gives you a relative number that actually means something.
Handy to know it ships wide open by default; that explains a few over-eager reads people have reported.
hahah but seriously good analysis