| Parameter | Unit | I-MON 256 USB | I-MON 512 USB | 
| Maximum number of FBG sensors | > 37 | > 70 | |
| Minimum FBG spacing | pm | 1200 | 1000 / 1200 | 
| Wavelength range | nm | 1525 – 1570 | 1275-1345/1510-1595 | 
| Wavelength fit resolution (*) | pm | < 0.5 | < 0.5 | 
| Repeatability (over any pol. state) | pm | 3 (5 max) | 3 (5 max) | 
| Wavelength accuracy | pm | 5 (typ) | 5 (typ) | 
| Wavelength drift (*) | pm / deg C | 1 (3 max) | 1 (3 max) | 
| Dynamic range | dB | 30 | 30 |