iotSDR

by embedINN

A versatile dev board with everything you need to design custom IoT protocols & gateways

View all updates Sep 18, 2020

Browsing the Sky For GNSS Satellites

by Abdul Malik Khan

The iotSDR has a Max2769 GNSS front-end chip capable of receiving on the GNSS L1 band. GNSS systems are similar, in some respects, to satellite communication systems. They provide a unique set of features that we believe justifies the inclusion of such a specialized receiver chip. Some of the features that we would like to discuss here include:

  1. Simplex communication (no two-way communication)
  2. Low transmit and receive power (a 25 W transmitter covers the globe)
  3. The receiver searches carrier-phase and Doppler measurements with very high sensitivity

To achieve their performance requirements, GNSS receivers typically rely on a specific front-end rather than a generic SDR front-end.

The GNSS chip on iotSDR has a transmit-only SPI interface for configuration and I/Q (or simple I) streaming. It can be configured in a variety of ways. For general usage, we have configured the chip to have a 16.384 MSPS sampling rate, with 4.092 MHz Intermediate Frequency (IF) streaming from 2-bit I and 2-bit Q interfaces. The block design in the FPGA Programmable Logic (PL) element of the ZYNQ SoC compacts 8 samples of 4-bit data into a 32-bit word, stores it in ping-pong memory, and makes it available to the ARM Processing System (PS) element of the SoC. The LwIP-based application in the PS transmits the logged data via UDP or TCP stream. That stream can be received on a host using a python script, a C++ application, or GNU Radio’s iotSDR module. Finally, the received data can be post-processed using available GNSS software-defined receivers.


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Product Choices

$599

iotSDR 7020

One iotSDR dev board with a Zynq XC7Z020 FPGA


$4

Ethernet cable (1M)

From the Crowd Supply Basics project.

Bel Ethernet Cable: RJ45 CAT5E Shield (1M). Connector ends: RJ45, wire gauge: 24 AWG, male / male.


$11

Active GPS Antenna

From the Crowd Supply Basics project.

A low-noise active GPS antenna suited for the GPS L1 band. Accepts 3-5V DC and outputs RF via an SMA(m) connector. Optional adhesive mounting.


$8

916 MHz Helical Monopole Antenna

From the Crowd Supply Basics project.

Order two for use with iotSDR.

916 MHz ISM Right Angle SMA Connector (LoRaWAN, HaLow, IoT Low-Profile Whip) by Linx Technologies


$4

LCW Dipole Antenna

From the Crowd Supply Basics project.

Order two for use with iotSDR.

2.4 GHz Dipole Tilt Swivel Antenna with SMA connector by Linx Technologies. Length: 83.1 mm


$6

430-435 MHz SMA Male Antenna

From the Crowd Supply Basics project.

Order two for use with iotSDR.

One single 433MHz Swivel Stick Dipole – SMA-M Stick Antenna by Pulse. (Image includes two antenna to show swivel capability.)


$10

microSD Card

From the Crowd Supply Basics project.

An industrial-grade memory card with extended endurance.

Credits

embedINN

Embedding things in reality.


Abdul Malik Khan

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