B. Petersen: SatNOGS 2685 - VE9EX-1

Introduction

1. The purpose of this page is to document the changes to my SatNOGS ground station.
2. The current parameter settings may be changed.
3. The current hardware is expected to be unchanged until August 2023.
4. If you have a suggestion for a change, hardware or software, please consider emailing me using b.petersen@ieee.org.

Links

System Versions

Hardware V05

Antenna Versions

Receiver

rtl_test

pi@raspberrypi:~ $ rtl_test
Found 1 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6 
[R82XX] PLL not locked!
Sampling at 2048000 S/s.

Info: This tool will continuously read from the device, and report if
samples get lost. If you observe no further output, everything is fine.

Reading samples in async mode...
Allocating 15 zero-copy buffers
lost at least 80 bytes

^CSignal caught, exiting!

User cancel, exiting...
Samples per million lost (minimum): 2
pi@raspberrypi:~ $ 

SoapySDRUtil -probe

pi@raspberrypi:~ $ SoapySDRUtil -probe
######################################################
##     Soapy SDR -- the SDR abstraction library     ##
######################################################

Probe device 
[INFO] [UHD] linux; GNU C++ version 8.3.0; Boost_106700; UHD_3.15.0.0-4satnogs1

RtApiAlsa::getDeviceInfo: snd_pcm_open error for device (default), No such file or directory.

Found Rafael Micro R820T tuner
[INFO] Opening Generic RTL2832U OEM :: 00000001...
Found Rafael Micro R820T tuner

----------------------------------------------------
-- Device identification
----------------------------------------------------
  driver=RTLSDR
  hardware=R820T
  index=0
  origin=https://github.com/pothosware/SoapyRTLSDR

----------------------------------------------------
-- Peripheral summary
----------------------------------------------------
  Channels: 1 Rx, 0 Tx
  Timestamps: YES
  Time sources: sw_ticks
  Other Settings:
     * Direct Sampling - RTL-SDR Direct Sampling Mode
       [key=direct_samp, default=0, type=string, options=(0, 1, 2)]
     * Offset Tune - RTL-SDR Offset Tuning Mode
       [key=offset_tune, default=false, type=bool]
     * I/Q Swap - RTL-SDR I/Q Swap Mode
       [key=iq_swap, default=false, type=bool]
     * Digital AGC - RTL-SDR digital AGC Mode
       [key=digital_agc, default=false, type=bool]
     * Bias Tee - RTL-SDR Blog V.3 Bias-Tee Mode
       [key=biastee, default=false, type=bool]

----------------------------------------------------
-- RX Channel 0
----------------------------------------------------
  Full-duplex: NO
  Supports AGC: YES
  Stream formats: CS8, CS16, CF32
  Native format: CS8 [full-scale=128]
  Stream args:
     * Buffer Size - Number of bytes per buffer, multiples of 512 only.
       [key=bufflen, units=bytes, default=262144, type=int]
     * Ring buffers - Number of buffers in the ring.
       [key=buffers, units=buffers, default=15, type=int]
     * Async buffers - Number of async usb buffers (advanced).
       [key=asyncBuffs, units=buffers, default=0, type=int]
  Antennas: RX
  Full gain range: [0, 49.6] dB
    TUNER gain range: [0, 49.6] dB
  Full freq range: [23.999, 1764] MHz
    RF freq range: [24, 1764] MHz
    CORR freq range: [-0.001, 0.001] MHz
  Sample rates: 0.25, 1.024, 1.536, 1.792, 1.92, 2.048, 2.16, 2.56, 2.88, 3.2 MSps


pi@raspberrypi:~ $ 

sudo satnogs-setup

SATNOGS_SOAPY_RX_DEVICE  *Define Soapy RX device [driver=rtlsdr]
SATNOGS_ANTENNA          *Define SatNOGS Radio Antenna [RX]
SATNOGS_RX_SAMP_RATE     *Define RX sampling rate [2.048e6]
SATNOGS_STATION_ELEV     *Define station elevation [90]
SATNOGS_STATION_ID       *Define station ID [2685]
SATNOGS_STATION_LAT      *Define station latitude [45.88201] 
SATNOGS_STATION_LON      *Define station longitude [-66.76792]

SATNOGS_RIG_IP                 Define Hamlib rigctld IP [127.0.0.1]
SATNOGS_RIG_PORT               Define Hamlib rigctld port [4532]
SATNOGS_DOPPLER_CORR_PER_SEC   Define doppler corrections per sec
SATNOGS_PPM_ERROR              Define frequency correction (ppm)
SATNOGS_LO_OFFSET              Define local oscillator offset (Hz)
SATNOGS_GAIN_MODE              Define SatNOGS Radio Gain mode (Overall, Settings Field) [Overall]
SATNOGS_RF_GAIN               *Define SatNOGS Radio RF Gain [29.7]
SATNOGS_RX_BANDWIDTH           Define SatNOGS Radio RF Bandwidth (Hz)
SATNOGS_ANTENNA               *Define SatNOGS Radio Antenna [RX]
SATNOGS_SOAPY_RX_DEVICE       *Define Soapy RX device [driver=rtl-sdr]
SATNOGS_RX_SAMP_RATE          *Define RX sampling rate [2.048e6]
SATNOGS_DEV_ARGS               Define SatNOGS Radio device arguments
SATNOGS_STREAM_ARGS            Define SatNOGS Radio stream arguments
SATNOGS_TUNE_ARGS              Define SatNOGS Radio tune arguments
SATNOGS_OTHER_SETTINGS         Define SatNOGS Radio other settings field options
SATNOGS_DC_REMOVAL             Enable automatic DC removal [True]
SATNOGS_BB_FREQ                Define SatNOGS Radio baseband frequency correction
ENABLE_IQ_DUMP                 Enable IQ dump [False]
IQ_DUMP_FILENAME               Define IQ dump filename
DISABLE_DECODED_DATA           Disable decoded data [False]
UDP_DUMP_HOST                  Destination host for UDP sink
UDP_DUMP_PORT                  Destination port for UDP sink

Computer

It is a RaspBerry Pi 4 with 8 GB or Ram and a 32 GB SD card. This ground station was created on 2022-05-30.

Comparisons

Discussion

1. The length of the feedline is relevant when using antenna A1 outside of its normal VHF and UHF frequency ranges. Specifically, for NOAA-15 and antenna A1, the received signals were better when the longer feedline A was used, compared to the short feedline B.
2. Antennas that match the polarization help, such a right-circular cross polarized antenna, such as antenna A3, for some satellites, as shown with S06 to S11.

Conclusions

1. The signals for antenna A1 often not strong.
2. Antenna A3 produces better UHF signals for passes with high elevation.
3. For S06, the RF gain needs to be reduced from 32.8 for strong signals, such as some ISS signals. A fixed RF gain would be a compromise.

Future Work

1. An azimuth-elevation rotator with directional signals would help.
2. Putting the antennas outside would help.
3. Adjusting the RTL-SDR parameters to the narrowest useable bandwidth may help.
4. A pre-amp may be considered, if the feedlines are long.
5. A different receiver may help.

Resources

1. https://network.satnogs.org/
2. https://wiki.satnogs.org/Main_Page
3. https://wiki.satnogs.org/SatNOGS_Client_Setup
4. https://wiki.satnogs.org/Omnidirectional_Station_How_To#Setting_the_gain
5. https://docs.satnogs.org/en/stable/
6. https://docs.satnogs.org/_/downloads/satnogs-config/en/0.5.3/pdf/
7. Good observations of others:
   1. NOAA-18 on 793 - F6KRK RX WX
   2. LUSAT on 2748 - EA1IW
   3. NOAA-15 on 1723 - ve2esm
   4. FOX-1B on 1723 - ve2esm, I was at Point Prim Lighthouse as XK2/VX9EX.
   5. FOX-1B on 2528 - KB3WFQ - V/U also recorded when I was at Point Prim Lighthouse. Compare 8:54 of the SatNOGS recording to an excerpt of my audio recording at files/2022-07-09-1321Z-AO-91-XK2-VX9EX-Point-Prim-Lighthouse.wav using a Yaesu-VX-8GR and and an Arrow II 146/440-14 (All suffixes), handheld satellite antenna, 4-element VHF Yagi and 10-element UHF Yagi, with a built in duplexer. The VHF downlink is loud on the audio. The UHF uplink is barely perceptible due to the manner in which it was recorded.
   6. ISS on 1723 - ve2esm