# **Pocket SDR - An Open-Source GNSS SDR, ver. 0.13** ## **Overview** Pocket SDR is an open-source GNSS (Global Navigation Satellite System) receiver based on the SDR (software defined radio) technology. It consists of RF frontend devices named "Pocket SDR FE", some utilities for the devices, and GNSS-SDR APs (application programs) written in Python, C, and C++. It supports almost all signals for GPS, GLONASS, Galileo, QZSS, BeiDou, NavIC, and SBAS. The Pocket SDR FE device consists of 2 or 4 RF frontend channels, which support GNSS L1 band (1525 - 1610 MHz), or L2/L5/L6 band (1160 - 1290 MHz). The bandwidth of each RF channel covers up to 36 MHz. The sampling rate of the ADC can be configured up to 32 Msps (FE 2CH) or 48 Msps (FE 4CH). The Pocket SDR also contains some utility programs for the Pocket SDR FE devices, to setup the devices, capture and dump the digitized IF (inter-frequency) data. These utilities support Windows, Linux, Raspberry Pi OS, macOS and other environments. The Pocket SDR also provides GNSS-SDR APs to show the PSD (power spectrum density) of captured IF data, search GNSS signals, track these signals, decode navigation data and generate PVT (position, velocity and time) solutions. The supported GNSS signals are as follows. For details on these signals and signal IDs used in the APs, refer [Pocket SDR Signal IDs](/doc/signal_IDs.pdf). * **GPS**: L1C/A, L1C-D, L1C-P, L2C-M, L5-I, L5-Q * **GLONASS**: L1C/A (L1OF), L2C/A (L2OF), L1OCd, L1OCp, L2OCp, L3OCd, L3OCp * **Galileo**: E1-B, E1-C, E5a-I, E5a-Q, E5b-I, E5b-Q, E6-B, E6-C * **QZSS**: L1C/A, L1C/B, L1C-D, L1C-P, L1S, L2C-M, L5-I, L5-Q, L5S-I, L5S-Q, L6D, L6E * **BeiDou**: B1I, B1C-D, B1C-P, B2a-D, B2a-P, B2I, B2b-I, B3I * **NavIC**: L1-SPS-D, L1-SPS-P, L5-SPS * **SBAS**: L1C/A, L5-I, L5-Q These utilities and APs are written in Python, C, and C++ by very compact way. They are easily modified by users to add user's unique algorithms.

Pocket SDR FEs (FE 2CH v.2.1, FE 2CH v.2.3, and FE 4CH v.3.0)

** The introduction of Pocket SDR is shown in the following slides. T.Takasu, An Open Source GNSS SDR: Development and Application, IPNTJ Next GNSS Technology WG, Feb 21, 2022 (https://gpspp.sakura.ne.jp/paper2005/IPNTJ_NEXTWG_202202.pdf) For an application of Pocket SDR, refer the following slides. T.Takasu, Development of QZSS L6 Receiver without Pilot Signal by using SDR, IPNTJ Annual Conference, June 10, 2022 (https://gpspp.sakura.ne.jp/paper2005/IPNTJ_20220610.pdf) -------------------------------------------------------------------------------- ## **Directory Structure and Contents** ``` PocketSDR --+-- bin Pocket SDR APs binary programs +-- app Pocket SDR APs source programs | +-- pocket_conf Pocket SDR FE device configurator | +-- pocket_dump Dump digital IF data of Pocket SDR FE device | +-- pocket_scan Scan and list USB devices | +-- pocket_acq GNSS signal acquisition | +-- pocket_trk GNSS signal tracking and PVT generation | +-- pocket_snap Snapshot Positioning +-- src Pocket SDR library source programs +-- python Pocket SDR Python scripts +-- lib Libraries for APs and Python scripts | +-- win32 Libraries for Windows | +-- linux Libraries for Linux or Raspberry Pi OS | +-- build Makefiles to build libraries | +-- cyusb Cypress EZ-USB API (CyAPI.a) and includes | +-- RTKLIB RTKLIB source programs based on 2.4.3 b34 | +-- (libfec) Library for FEC (forward error corrections) ([1]) | +-- (LDPC-codes) Library for LDPC-decoder ([2]) +-- conf Configuration files for Pocket SDR FE +-- FE_2CH Pocket SDR FE 2CH H/W and F/W +-- FE_4CH Pocket SDR FE 4CH H/W and F/W +-- driver Windows driver for Pocket SDR FE +-- doc Documents +-- image Image files for documents +-- sample Sample digital IF data captured by Pocket SDR FE +-- test Test codes and data () : not included in the package ``` -------------------------------------------------------------------------------- ## **Installation for Windows** * Extract PocketSDR.zip or clone the git repository (https://github.com/tomojitakasu/PocketSDR) to an appropriate directory . * Attach Pocket SDR FE to PC via USB cable. * Install USB driver (CYUSB) for Pocket SDR RF frontend according to PocketSDR\driver\readme.txt. * Add the Pocket SDR binary programs path (\PocketSDR\bin) to the command search path (Path) of Windows environment variables. * Add the Pocket SDR Python scripts path (\PocketSDR\python) to the command search path (Path) of Windows environment variables. * To rebuild the binary programs, you need MinGW64. Refer MSYS2 (https://www.msys2.org/) for details. * In MinGW64 environment, you need fftw3 library. To install fftw3 library. ``` $ pacman -S mingw-w64-x86_64-fftw ``` -------------------------------------------------------------------------------- ## **Installation for Linux or Raspberry Pi OS** * You need fundamental development packages and some libraries. Confirm the following packages exist: gcc, g++, make, libusb-1.0-0-dev, libfftw3-dev, python3, python3-numpy, python3-scipy, python3-matplotlib * Extract PocketSDR.zip or clone the git repository to an appropriate directory . ``` $ unzip PocketSDR.zip or $ git clone https://github.com/tomojitakasu/PocketSDR ``` * Move to the library directory, install external library source trees ([1], [2]) as follows: ``` $ cd /lib $ chmod +x clone_lib.sh $ ./clone_lib.sh ``` * Move to the library build directory and build libraries. ``` $ cd /lib/build $ make $ make install ``` * Move to the application program directory and build utilities and APs. ``` $ cd /app $ make $ make install ``` * Add the Pocket SDR binary programs path (/PocketSDR/bin) to the command search path. * Usually you need to have a root permission to access USB devices. So you have to add "sudo" to execute pocket_conf, pocket_dump like: ``` $ sudo pocket_conf ../conf/pocket_L1L6_12MHz.conf $ sudo pocket_dump -t 10 ch1.bin ch2.bin ``` -------------------------------------------------------------------------------- ## **Installation for macOS** * You need Homebrew as a package manager for macOS. Install Homebrew according to the following link. https://brew.sh/ * Open a terminal window on macOS and install the basic libraries by using Homebrew: ``` $ brew install numpy $ brew install scipy $ brew install python-matplotlib $ brew install python-tk $ brew install tcl-tk $ brew install libusb ``` * Extract PocketSDR.zip or clone the git repository to an appropriate directory . ``` $ unzip PocketSDR.zip or $ git clone https://github.com/tomojitakasu/PocketSDR ``` * Move to the library directory, install external library source trees ([1], [2]) as follows: ``` $ cd /lib $ chmod +x clone_lib.sh $ ./clone_lib.sh ``` * Move to the library build directory and build libraries. ``` $ cd /lib/build $ make $ make install ``` * Move to the application program directory and build utilities and APs. ``` $ cd /app $ make $ make install ``` * Add the Pocket SDR binary programs path (/PocketSDR/bin) to the command search path. -------------------------------------------------------------------------------- ## **Utility Programs for Pocket SDR FE** Pocket SDR contains the following utility programs for the Pocket SDR FE. - **pocket_conf**: Pocket SDR FE device configurator - **pocket_scan**: Scan and list USB Devices - **pocket_dump**: Capture and dump digital IF data of Pocket SDR FE device For details, refer comment lines in src/pocket_conf.c, src/pocket_scan.c, src/pocket_dump.c. -------------------------------------------------------------------------------- ## **GNSS-SDR APs (Application Programs)** Pocket SDR contains the following application programs for GNSS-SDR. - **pocket_psd.py** : Plot PSD and histograms of digital IF data - **pocket_acq.py** : GNSS signal acquisition in digital IF data - **pocket_trk.py** : GNSS signal tracking and navigation data decoding in digital IF data - **pocket_snap.py**: Snapshot positioning with digital IF data - **pocket_plot.py**: Plot GNSS signal tracking log by pocket_trk.py - **pocket_sdr.py** : GUI-based GNSS-SDR receiver - **pocket_acq** : C-version of pocket_acq.py (w/o graph plots) - **pocket_trk** : C-version of pocket_trk.py (w/o graph plots) - **pocket_snap** : C-version of pocket_snap.py For details, refer comment lines in python/pocket_psd.py, python/pocket_acq.py, python/pocket_trk.py, python/pocket_snap.py and python/pocket_plot.py. You need Python 3, Numpy, Scipy and matplotlib to execute Python scripts. -------------------------------------------------------------------------------- ## **GUI-based GNSS-SDR Receiver AP** In ver.0.13, GUI-based GNSS-SDR receiver AP "Pocket SDR" is added. To execute the AP: ``` $ chmod +x /python/pocket_sdr.py $ .//python/pocket_sdr.py or $ python /python/pocket_sdr.py ``` You can see the Pocket SDR AP window. If you connect Pocket SDR FE 2CH or 4CH to the PC, push the button "Start" top of the window to launch the GNSS-SDR receiver. To stop the receiver, push the button "Stop". The detailed instructions for the AP will be added later as a manual.

-------------------------------------------------------------------------------- ## **Execution Examples of Utility Programs and GNSS-SDR APs** ``` $ sudo pocket_conf ... $ sudo pocket_conf conf/pocket_L1L6_12MHz.conf Pocket SDR device settings are changed. $ sudo pocket_dump -t 5 ch1.bin ch2.bin TIME(s) T CH1(Bytes) T CH2(Bytes) RATE(Ks/s) 5.0 I 60047360 IQ 120094720 11985.5 $ pocket_psd.py ch1.bin -f 12 -h $ pocket_acq.py ch1.bin -f 12 -sig L1CA -prn 1-32,193-199 SIG= L1CA, PRN= 1, COFF= 0.23492 ms, DOP= -1519 Hz, C/N0= 33.6 dB-Hz SIG= L1CA, PRN= 2, COFF= 0.98558 ms, DOP= 2528 Hz, C/N0= 33.8 dB-Hz SIG= L1CA, PRN= 3, COFF= 0.96792 ms, DOP= 3901 Hz, C/N0= 33.7 dB-Hz SIG= L1CA, PRN= 4, COFF= 0.96192 ms, DOP= -1957 Hz, C/N0= 40.4 dB-Hz ... $ pocket_acq.py ch1.bin -f 12 -IQ 1 -sig L1CA -prn 4 $ pocket_acq.py ch1.bin -f 12 -IQ 1 -sig L1CA -prn 8 -3d $ pocket_acq.py ch2.bin -f 12 -sig L6D -prn 194 -p $ pocket_trk.py ch1.bin -f 12 -IQ 1 -sig L1CA -prn 1-32 TIME(s): 4.90 SRCH: 0 LOCK: 9/ 32 CH SAT SIG PRN LOCK(s) C/N0 (dB-Hz) COFF(ms) DOP(Hz) ADR(cyc) SYNC #NAV #ERR #LOL NER 5 G05 L1CA 5 4.89 47.3 ||||||||||| 0.7176882 958.2 4687.7 -B-- 0 0 0 0 6 G06 L1CA 6 4.89 41.7 ||||||| 0.6283584 -3510.3 -17163.6 -B-- 0 0 0 0 7 G07 L1CA 7 4.89 40.5 ||||||| 0.6468045 -1258.6 -6152.3 -B-- 0 0 0 0 11 G11 L1CA 11 4.89 46.7 ||||||||||| 0.1002834 -1660.3 -8114.1 -B-- 0 0 0 0 13 G13 L1CA 13 4.89 47.8 ||||||||||| 0.1235314 1803.9 8825.4 -B-- 0 0 0 0 15 G15 L1CA 15 4.89 40.3 |||||| 0.8688543 2864.4 14011.2 -B-- 0 0 0 0 20 G20 L1CA 20 4.89 46.5 |||||||||| 0.4835166 -161.2 -789.3 -B-- 0 0 0 0 29 G29 L1CA 29 4.89 44.5 ||||||||| 0.4977522 429.7 2108.4 -B-- 0 0 0 0 30 G30 L1CA 30 4.89 44.2 ||||||||| 0.7357694 540.2 2643.5 -B-- 0 0 0 0 ... $ pocket_trk.py ch1.bin -f 12 -IQ 1 -sig E1B -prn 18 -p ... $ pocket_trk.py ch2.bin -f 12 -sig E6B -prn 4 -log trk.log -p -ts 0.2 ... ```

-------------------------------------------------------------------------------- ## **Real-time GNSS Signal Tracking with Pocket SDR FE and pocket_trk AP** With the Pocket SDR FE device and the AP pocket_trk, you can track GNSS signals and generate PVT solutions in real-time. In this case, the sampling frequency, IF frequencies, sampling type (I or I/Q), RF channel selections are automatically configured according to the device info obtained from the device. Multiple GNSS signals and PRN numbers can be specified as pocket_trk options -sig and -prn. On Linux or Raspberry Pi OS, you might have to add "sudo" to access the Pocket SDR FE device. ``` $ pocket_trk -sig L1CA -prn 1-32 -sig L5I -prn 1-32 ``` As default, the signal tracking status are shown as the following example. ``` 2024-05-30 08:39:50.996 35.1234065 138.1234560 1234.45 8/ 9 FIX BUFF: 1% SRCH: 17 LOCK: 11/ 32 CH RF SAT SIG PRN LOCK(s) C/N0 (dB-Hz) COFF(ms) DOP(Hz) ADR(cyc) SYNC #NAV #ERR #LOL FEC 5 1 G05 L1CA 5 52.14 47.5 ||||||||||| 0.6361186 779.8 41233.8 -BFR 7 0 0 0 6 1 G06 L1CA 6 52.05 40.7 ||||||| 0.0092524 -3740.1 -194068.1 -BF- 7 0 0 0 ... ``` The first line of the status indicates: ``` 2024-05-30 08:39:50.996: Signal reception time expressed in GPS time 35.1234065 : PVT solution latitude (deg, +: north, -: south) 138.1234560 : PVT solution longitude (deg, +: east, -: west) 1234.45 : PVT solution ellipsoidal height (m) 8/ 9 : Numbers of satellites for PVT and all tracking satellites FIX : FIX PVT fixed, --- PVT not available BUFF: 1% : Internal IF data buffer usage rate (overloaded if exceeding 100%) SRCH: 17 : Signal search channel number LOCK: 11/ 32: Numbers of signal lock channels and all channels ``` The third and following lines of the status indicates: ``` CH : Receiver channel number (1-999) RF : RF frontend RF channel number (1-4) SAT : GNSS satellite (Gnn: GPS, Rnn: GLONASS, Enn: Galileo, Jnn: QZSS, Cnn: BeiDou, Inn: NavIC, Snn: SBAS) SIG : GNSS signal ID PRN : PRN number or FCN for GLONASS FDMA LOCK: Continuos lock time (s) C/N0: C/N0 (dB-Hz) and C/N0 bar COFF: Tracking PRN code offset (ms) DOP : Doppler frequency (Hz) ADR : Accumulated Doppler range (cycle) SYNC: Synchronization status (secondary code, bit, frame, and polarity) #NAV: Number of properly decoded navigation subframes or messages #ERR: Number of error navigation subframes or messages #LOL: Number of loss-of-lock trackings FEC : Number of corrected error bits by FEC (-1: unrecoverable errors) ``` The GNSS PVT solutions can be output as NMEA 0183 format ([3]) by -nmea option. ``` $ pocket_trk -sig L1CA -prn 1-32 -nmea ``` The path is just a local file path. To output data to outside of the AP, use :port as the path to accept connections by a TCP server, or address:port to connect an external TCP server. The GNSS observation data and navigation data can be output as RTCM3 MSM7 and navigation data formats ([4]) by -rtcm option. ``` $ pocket_trk -sig L1CA -prn 1-32 -rtcm ``` The GNSS signal tracking log including observation data and HEX dump of navigation data can be output by -log option. ``` $ pocket_trk -sig L1CA -prn 1-32 -log ```

-------------------------------------------------------------------------------- ## **References** [1] https://github.com/quiet/libfec [2] https://github.com/radfordneal/LDPC-codes [3] NMEA 0183, Standard for Interfacing Marine Electronic Devices, National Marine Electronics Association and International Marine Electronics Assosiation, 2013 [4] RTCM 10403.3 with Amendment 1, Differential GNSS (Global Navgation Satellite Systems) service - version 3, Radio Technical Commission for Maritime Services, April 28, 2020 -------------------------------------------------------------------------------- ## **History** * 2021-10-20 0.1 1st draft version * 2021-10-25 0.2 Add Rebuild F/W and Write F/W Image to PocketSDR * 2021-12-01 0.3 Add and modify Python scripts * 2021-12-25 0.4 Add and modify Python scripts * 2022-01-05 0.5 Fix several problems. * 2022-01-13 0.6 Add and modify Python scripts * 2022-02-15 0.7 Improve performance, Add some Python scripts. * 2022-07-08 0.8 Add C-version of pocket_acq.py and pocket_trk.py. * 2024-01-03 0.9 Add C-version of pocket_snap.py. pocket_trk supports multi-signal and multi-threading * 2024-01-12 0.10 Support NavIC L1-SPS-D, L1-SPS-P, GLONASS L1OCd, L1OCp and L2OCp. * 2024-01-25 0.11 Support decoding of GLONASS L1OCd NAV data Support NB-LDCP error correction for BDS B1C, B2a and B2b * 2024-05-28 0.12 Performance optimized. Support PVT generation, RTCM3 and NMEA outputs * 2024-07-04 0.13 GUI-based GNSS-SDR receiver AP added. Support macOS.