This measurement is captured on an external USB flash drive. The captured data file can not be recalled and displayed on the instrument screen.
The LMR Master can capture and log NXDN IQ data to a USB flash drive.
1. From the Frequency main menu, set the receiver frequency (Rx Freq).
2. From the Setup main menu, choose a Mod Bandwidth.
3. Insert a formatted USB flash drive into the LMR Master and from the Measurement main menu, press the NXDN IQ Capture submenu key. After approximately 10 seconds the instrument will display a message that the capture is complete.
The IQ data is sampled at 2,400 x 11 (6.25 kHz BW) or 4,800 x 11 (12.5 kHz BW) symbols per second. The saved file has an ASCII header and binary data (Figure: IQ Capture (6.25 kHz Bandwidth)). The data is written in 24‑bit two’s complement integers format. Interleaved Delta Phase (I) data then Magnitude (Q) data is captured. The file is intended for post‑processing in MATLAB or similar software.
The file will be written to a data stamped folder inside the /usr folder on the root level of the USB flash drive. The file is named:
IQ_CAPTUREyearmonthdaytime.nxdn
Note
There is no display menu for NXDN IQ Capture. The LMR Master will continue to display the previous measurement screen during IQ Capture.
