ThumbNet N3 SDR Receiver
ThumbSat
Compact USB SDR receiver dongle for ThumbNet citizen-science ground stations, tuned for 400MHz-band ThumbSat downlink and ADS-B reception, built around the R820T2/RTL2832U chipset.
Technical specifications
- Tuner IC
- R820T2
- Demodulator
- RTL2832U
- EEPROM
- 24C02
- Frequency range
- 24 MHz - 1766 MHz (approx. 13-1864 MHz with experimental drivers)
- Input impedance
- 75 ohm
- ADC resolution
- 8-bit (practical 7-7.5 bit with oversampling)
- Clock stability
- High-stability TCXO, +/-0.5 ppm
- Power consumption
- ~410 mA, USB-powered, optional external 5V DC input
- Board dimensions
- 6 x 4 cm
- Connectors
- Mini-USB (host), F-type RF (antenna)
- Enclosure compatibility
- 1455-series case
- Performance vs. ThumbNet v1
- ~15 dB higher signal strength; 10-15% more ADS-B messages/aircraft reports; lower background noise
- Price
- $25.75 per unit
About
The ThumbNet N3 is the current-generation software-defined radio receiver used by ThumbSat’s ThumbNet ground-station network, the global system of internet-connected, largely volunteer- and student-operated stations that receive and relay ThumbSat mission data. Built around the R820T2 tuner and RTL2832U demodulator with a 24C02 EEPROM and a high-stability +/-0.5ppm TCXO clock, the N3 covers roughly 24 MHz to 1766 MHz (extendable to about 13-1864 MHz with experimental drivers) with 75 ohm input impedance and 8-bit ADC (practical resolution about 7-7.5 bits with oversampling). It is USB-powered (about 410 mA) with an optional external 5V DC input, connects via mini-USB to the host/tracking-station computer and via F-type RF connector to the ThumbNet Yagi antenna, and is housed on a compact 6x4cm PCB using standard 0603-or-larger surface-mount components, fitting a standard 1455 enclosure. Compared with the earlier ThumbNet v1 dongle, the N3 delivers roughly 15dB higher signal strength and 10-15% more ADS-B messages and aircraft reports with reduced background noise and waterfall distortion, and is used both for tracking ThumbSat femtosatellite downlinks and for general ADS-B/SDR reception in the ThumbNet virtual classroom curriculum.
Documentation
No public datasheet yet — request the datasheet / ICD from the supplier.
