D325f-SDR LG Phone SDR Update: App 2.0, Meteor-M HRPT Reception and an SNR Comparison Against the RTL-SDR Blog V4
Back in October, we posted about D325f-SDR, a project from Logan Zarov that turns the Qualcomm cellular modem in an old LG D325 Android phone into an SDR, using the phone's own Bluetooth transmitter as a local oscillator to reach below 800 MHz. Logan has written in again about some updates to the software.
Version 2.0 of the app adds scheduled recordings with the screen off, recovery after modem failures, an IQ inversion switch, and Bluetooth channel and power settings. Logan has also received Meteor-M N2-3 HRPT at 1.7 GHz with a homemade helix feed and dish, and decoded it into an image with SatDump. MetOp-B AHRPT reaches frame sync, but Reed-Solomon decoding still fails.
Logan also compared CW SNR against our RTL-SDR Blog V4 in a shielded box. The LG came out ahead from 417 to 717 MHz and above 1 GHz, but behind below 400 MHz. Logan notes that these are preliminary, uncalibrated results. Logan also estimates the default Bluetooth LO level at about 3.5 mW, under the 10 mW EIRP limit in the EU/UK and Russia, but notes that in the US only levels 0 to 5 fit under FCC 15.249. Raw files and more results are in the project's field notes.
Logan has also posted a video showing how the phone's hardware is modified to allow for an external antenna via the phone's 3.5mm headphone jack. The video also shows how to patch the software and shows Logan receiving various signals and bands on the phone, including broadcast FM, shortwave, VHF, UHF, a 1875 MHz cell base station downlink, and finally a 1.7 GHz HRPT weather satellite image from Meteor-M N2-3.
AI Disclaimer: The project's credits note that AI tools assisted with code development and documentation.
