Introduction

GNSSDO
SKU: GPS-26289

Purchase from SparkFun
Designed and manufactured in Boulder, Colorado, USA, the SparkPNT GNSSDO is the perfect solution for your high-precision timing needs. Based around the multi-constellation, multi-frequency, L5-ready mosaic-T from Septentrio, this is our most accurate GNSS timing product to date. It features a SiTime SiT5358 disciplined 10MHz Digitally-Controlled Temperature-Controlled Crystal Oscillator (DCTCXO) providing excellent clock accuracy, stability and holdover. The mosaic-T also has built-in on-module support for the Fugro AtomiChron L-band timing service.

Under the hood, the GNSSDO is based on the mosaic-T GNSS module from Septentrio, plus the Espressif ESP32-WROVER processor (16MB flash, 8MB PSRAM). The mosaic-T has USB-C connectivity (with Ethernet-over-USB), multiple UARTs and supports full Ethernet connectivity. You can connect the mosaic-T directly to your Ethernet network - our product supports Power-over-Ethernet too. The ESP32 rides shotgun, disciplining the DCTCXO and controlling the OLED display. The GNSSDO has multiple power options including USB-C, PoE and 9V-36V DC, making it easy to connect it to a battery-backed supply. Robust SMA connections and screw cage terminals provide access to the Pulse-Per-Second and 10MHz clock signals.
Features
- Septentrio mosaic-T multi-constellation, multi-frequency GNSS timing receiver
  - Accurate and resilient with dedicated timing features
  - Highly secure against jamming and spoofing with AIM+ unique interference mitigation technology combined with Fugro AtomiChron services
  - Update rate of 10 Hz
  - 448 hardware channels for simultaneous tracking of all visible supported satellite signals:
    - GPS: L1C/A, L1PY, L2C, L2P, L5
    - GLONASS: L1CA, L2CA, L2P, L3 CDMA
    - Beidou: B1I, B1C, B2a, B2b, B2I, B3
    - Galileo: E1, E5a, E5b, E5 AltBoc, E6
    - QZSS: L1C/A, L1 C/B, L2C, L5
    - NavIC: L5
    - SBAS: Egnos, WAAS, GAGAN, MSAS, SDCM (L1, L5)
    - On-module L-band
  - Supports RTCM input for RTK Rover. RTCM output (RTK Base) is not supported.
  - Time pulse precision: 5ns
  - Time pulse precision with AtomiChron (L-Band or IP): < 1ns
  - Event accuracy: < 20ns
  - Operating temperature: -40 to 85 °C
  - USB-C interface (UART and Ethernet-over-USB)
- ESP32-WROVER processor (16MB flash, 8MB PSRAM)
  - USB-C interface (UART via CH340)
- SiT5358 disciplined 10MHz oscillator
  - ±50ppb stability
  - ±1ppb/°C frequency slope
  - ±58ppb typical 20-year aging
  - Digital frequency pulling via I²C
  - Allan Deviation approaches 1E-14 at 10000 seconds with AtomiChron enabled
  - Operating temperature: -40 to 85 °C (Industrial)
- microSD socket
  - Connected directly to the mosaic-T for fast data logging
- OLED display
  - 128x64 pixels
- Status LEDs
Connectivity Options
- SMA Connections:
  - GNSS Antenna (L1/L2/L5/L-Band) - provides 3.3V for an active antenna
  - 10MHz Output - disciplined, configurable for 5V / 3.3V / 2.8V / 1.8V and 50 Ohm
  - 10MHz Input - switchable, input impedance 50Ω, detection level -14dBm, max supported level +12dBm
  - Pulse-Per-Second Square Wave - configurable for 5V / 3.3V / 2.8V / 1.8V and 50 Ohm
  - EventA Input - configurable for 5V / 3.3V / 2.8V / 1.8V and 50 Ohm
- 3.5mm Screw Cage Connections:
  - 9V-36V DC input (isolated)
  - GND
  - mosaic-T COM2 (TX/RX/CTS/RTS) - 3.3V / 5V switchable
  - CTS can be configured as a 3.3V / 5V power output via a solder jumper
  - EventB input - 3.3V / 5V switchable
  - I²C (SCL2 / SDA2) for an external TCXO / OCXO - 3.3V / 5V switchable
- Ethernet:
  - KSZ8041NLI Ethernet PHY interface
  - 10Base-T / 100Base-TX with auto-negotiate and Auto MDI/MDI-X
- Power Options:
  - USB-C
  - Power-over-Ethernet (PoE)
  - 9V-36V DC input (fully isolated)
RTK Base

The mosaic-T is a superb GNSS module designed for highly accurate timing applications. It can be configured as a RTK Rover and will make use of incoming RTCM corrections. However, it can NOT be configured as a RTK Base because the RTCM output is not supported.

Product Comparison

Below is a simple comparison table between our breakout board and Septentrio's development and evaluation kits:

	mosaic-T Development Kit	mosaic-go Evaluation Kit	mosaic-X5 GNSS Breakout	RTK mosaic-X5	GNSSDO
RTK Rover	Yes	Yes	Yes	Yes	Yes
RTK Base	Yes	Yes	Yes	Yes	No
GNSS Antenna	Dual	Single (mosaic-X5) Dual (mosaic-H)	Single	Single	Single
USB Connector	micro-B	micro-B	Type-C	Type-C	Type-C
Ethernet	Yes 10/100 Base-T	No	No	Yes 10/100 Base-T	Yes 10/100 Base-T
WiFi	No	No	No	Yes - Network Bridge 10 Base-T	No
COM Ports	4	2	4	1 - mosaic-X5 1 - ESP32	1 - mosaic-T 1 - ESP32
µSD Card Slot	Yes	Yes	Yes	Yes	Yes
Reset/Log Buttons	Yes	No*	Yes	Yes	Yes
Logic-Level	1.8V 3.3V	3.3V	3.3V	3.3V 5V	3.3V 5V
PPS Signal	Header Pin	6-Pin JST Connector	SMA Connector	Screw Terminal	SMA Connector
10MHz Signal	SMA Connector In Only	No	No	No	SMA Connector In/Out
Enclosure Material	N/A	Metal	N/A	Aluminum	Aluminum
Dimensions	N/A	71 x 59 x 12mm ± 1mm	70.9 x 50.8 x 8mm	180.6 x 101.8 x 41mm Enclosure Only	180.6 x 101.8 x 41mm Enclosure Only
Weight	N/A	58g ± 1g	22.6g	415.15g Enclosure Only	415.15g Enclosure Only

mosaic-go Evaluation Kit

The reset pin is exposed on 4-pin JST connector and the log pin is connected to the latch pin of the SD card slot.

Required Materials

The GNSSDO comes with everything you need to get up and running.

Kit Contents

The linked product does not include the front/rear panels and stickers for the GNSSDO. Additionally, the product only features a red anodized plating and is not powder coated in the Septentrio orange.

Mounting Hardware

This kit does not include any mounting hardware for the antenna. If you wish to permanently mount the antenna outside, we recommend the following products:

Tip

If needed, use an extension cable to reach your installation location. We have daisy chained up to three RG58 10m cables with a marginal loss in signal strength.

Extension Cables

Your GNSSDO is equally at home on your desk, lab bench, or in a server rack. But you're still going to want to put the GNSS antenna outdoors, so it will have the best view of the sky. Some extra SMA extension cables may be useful. The GNSS SMA antenna connection from the SparkPNT GNSSDO has a standard polarity.

For shorter extensions, we have RG178 cables in 1m and 25cm lengths. For longer extensions, we have higher quality, low-loss RG58 10m cables available in our catalog.

SMA Adapters

We have several adapters for users who need to connect to the EVENTA, PPS, and/or 10MHz signals for their server or test equipment. These SMA connections from the SparkPNT GNSSDO have a standard polarity.

Selecting an Outdoor Enclosure

The GNSSDO comes in a beautiful custom extruded aluminum enclosure, with machined end panels and matching stickers. The slotted flanges make it easy to install and secure the enclosure in many locations. But the enclosure only provides limited protection against the ingress of dust and water; it is designed to IP42. So, if you are going to permanently install it up on the roof too, you're going to need a suitable weatherproof box. We found a good one - the Orbit 57095 - also available from Amazon - back when we put together our very first DIY GNSS Reference Station.

How to Build a DIY GNSS Reference Station

AC Not Required!

The Orbit enclosure comes with a built-in power outlet, but you don't need it! The GNSSDO can be powered by Power-over-Ethernet (PoE), meaning all you really need to run up to the roof is a standard 8-core CAT-6 Ethernet cable. Choose a PoE Ethernet Switch that meets your needs. We have had good experiences with the TP-Link TL-SG1005P - available from many retailers including Amazon.

Introduction

Required Materials

Suggested Reading