Setup Guide
Table Of Contents
- Notices
- About Thinkify, LLC
- A Quick RFID Introduction
- Thinkify Reader Protocol Overview
- Command Reference
- Summary
- "A" – RX Amplifier Control
- "BOOTLOADER" – Enter Bootloader
- "C" – Low-Level Chip Control Registers
- "F" – RX Filter Control
- "G" – GPIO Settings
- “I” – Inventory Control
- "K" – Kill, Lock, Access Descriptors
- “M" – MASK / SELECT control
- “NM" – Macro Control
- "P" – PROTOCOL control (Gen2 Air protocol)
- "R" – RF Control
- "RP" and "RM" – Multiplexing (Antenna Control)
- "T" – Initiate INVENTORY
- "X" – eXtra Data Read and Write Descriptor Control
"T" – Initiate INVENTORY
TAG=3000BAD100000000000000000000 908250 00 5 0 I D3EB
TAG=3000BAD100000000000000000000 908250 03 5 0 I D3FC
TAG=3000E2003411B801010861355058 908250 02 A 7 Q D409
STOPINVENTORY 0x0062 EPCCOUNT=6
Calculating Signal Strength (RSSI) from the I/Q Magnitude Fields
Tag data returned from a Tn inventory (where n= 2,4,6) include fields for I and Q signal
magnitude. You can use these fields to calculate an overall signal strength for the read that can
give you some indication of the range of the tag to the antenna.
In desktop applications like programming, this is especially useful to discriminate between a tag
that is right next to the antenna vs. one some distance away. You may choose to filter the data
reported to an end user of your application by signal strength to only show nearby tags. –
One of the example programs provided by Thinkify in the TR200 developer's kit does just this.
Recall the magnitudes are delivered as part of a tag read message:
TAG=3000E2003411B801010861355058 908250 02 A 7 Q D409
(Here the I channel magnitude is A (decimal 10) and the Q channel magnitude is 7.)
To calculate the signal strength, use the following relationship:
rssi = 2 * high_rssi + 10 * Log(1 + 10 ^ (-delta_rssi / 10))
Where:
high_rssi = 10
(the larger RSSI is the I channel with a value of A.(10 decimal)) and
delta_rssi = Abs(imag – qmag)
delta_rssi = 3
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