Radio Frequency Identification (RFID) technology is more widely used.
In particular, UHF RFID technology is attracting more and more because of its advantages including reading and write distance. Power amplifiers occupy the majority of energy consumption in the power consumption of UHF readers. In most applications, to maximize the read distance, transmit power is usually set to a maximum which results in a waste of energy.
To maximize the battery life of an RFID reader it is, therefore, necessary to save energy. But how can you do it?
Below, taking into consideration the BlueBerry HS UHF portable passive reader, we will analyze two different approaches that will allow you to decrease power consumption, thus preserving the device’s battery. In particular,
- Decrease the RF power level in which the reader is operating;
- Use the RF-off time parameter inside the firmware in order to apply the duty cycle functionality.
These two approaches can be used simultaneously. Now, let’s start analyzing them one by one!!!
Decrease the RF power level
First of all, what is the RF power level? It is the amount of RF energy emitted from an RFID tag reader. The higher the power output the longer the read range. So when you want to maximize the read range, you have to know that the reader consumes a large amount of power because it is operating at full RF power. Accordingly, setting the RF power down, it’s an easy way to reduce power consumption. Obviously, don’t forget that the decrease of the RF power level will be at the expense of the reading range which will shorten!
However, the decrease of the two parameters is not linear. That is, if you halve the RF power level, energy consumption decreases not by half, but by a much smaller amount. The decrease is therefore not efficient. This is because the RF power amplifiers (PAs) depends on many factors and above all must be adapted to the output power loads. The efficiency of PAs varies directly with the output power levels, so if the efficiency drops drastically as the output power level is reduced.
Use an RF off time parameter in continue scanning mode
To conserve power consumption in continue scanning mode, it is possible to turn off the RF power amplifier for a selected time interval. Taking into consideration BlueBerry HS UHF, a practical example is to avoid duty cycles greater than 0.5 (600ms ON, 400ms OFF), but to prefer periods configured as 200ms ON and 800ms OFF. So, the longer the RF off range is extended, the more power consumption saved, on the other hand the reader will have less reactive reading ability. Unlike the approach previously discussed, this will not affect the reading distance
In conclusion, to resume:
|Decrease the RF power level||A simple way to preserve battery, if the read range does not represent an issue||Not efficient in term of power savings|
|Use an RF off time parameter in continue scanning mode||Decreases the energy consumption without affecting the reading distance||The reactive ability in reading is reduced|
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