JRC NWZ-4740 Antenna Unit JLR-4341 (DGPS 224) with cable

The JRC NWZ-4740 Antenna Unit, often specifically identified as the JLR-4341 (DGPS 224) and supplied with its connecting cable, is a crucial component of a JRC Global Navigation Satellite System (GNSS) receiver, typically used for DGPS (Differential GPS) applications. This robust external antenna is engineered to precisely receive satellite signals from constellations like GPS, GLONASS, Galileo, and BeiDou, along with differential correction signals (e.g., from SBAS like WAAS/EGNOS or external DGPS beacons) to enhance positioning accuracy. Designed for harsh marine environments, it integrates the necessary receiving elements and pre-amplification circuitry within a durable, weather-resistant housing. The accompanying cable ensures reliable transmission of the raw satellite signal data from the antenna’s exposed mounting location (e.g., mast, radar arch) down to the main JRC GNSS receiver unit located within the vessel’s protected interior, enabling the system to calculate highly accurate and reliable position fixes, essential for safe navigation and precise vessel operations.

Technical Specification

Satellite Reception:

GNSS Compatibility: Receives signals from multiple satellite constellations.
- GPS: L1 (1575.42 MHz)
- GLONASS: L1 (1602.0 MHz)
- SBAS (Satellite-Based Augmentation System): WAAS, EGNOS, MSAS, GAGAN (for differential corrections)
DGPS Compatibility (via internal receiver or separate input):
- Beacon Receiver Frequency Range (if integrated): Typically 283.5 kHz to 325 kHz for international DGPS beacon services (though the antenna itself receives the satellite signals, the DGPS capability relies on the connected receiver unit). The “DGPS 224” in the model name often implies its readiness for DGPS.

Performance Characteristics (Antenna’s Contribution to System Performance):

Antenna Gain: (Specific value not usually published for end-users, but designed for optimal marine reception).
Noise Figure: Low, to ensure good signal quality.
Output Signal: Raw satellite signal data (RF signal at L-band frequencies) to the connected JRC GNSS receiver unit for processing.

Electrical:

Power Supply: Power Over Coax (POC) – supplied directly through the antenna cable from the connected JRC GNSS receiver unit.
Voltage: Typically 5 VDC from the receiver (exact voltage can vary slightly depending on the specific receiver model).
Current Consumption: Low, usually in the range of 30-100 mA.

Physical:

Design: Compact, robust, dome-shaped or cylindrical marine-grade enclosure.
Mounting: Designed for pole mount or surface mount on a mast, radar arch, or cabin top, ensuring a clear sky view. Standard 1″ x 14 TPI marine mount is common.
Connector: TNC-type (or similar robust RF connector) for antenna cable connection.
Dimensions:
- Diameter: Approx. 100-150 mm (4-6 inches)
- Height: Approx. 80-120 mm (3-5 inches)
- Note: Exact dimensions require checking the specific JLR-4341 manual.
Weight: Lightweight, typically under 1 kg (2.2 lbs).
Cable: Supplied with a dedicated coaxial cable of varying length (e.g., 10m, 20m, 30m) for connection to the main receiver unit. The cable specification is crucial for signal integrity.

Environmental:

Ingress Protection (IP) Rating: IPX6 or IPX7 (highly waterproof, protected against strong jets of water or temporary immersion), essential for exposed outdoor marine installation.
Operating Temperature: Typically $- 2 5^{\circ} C$ to $+ 7 0^{\circ} C$ (or wider, $- 4 0^{\circ} C$ to $+ 8 5^{\circ} C$ ).
Storage Temperature: $- 4 0^{\circ} C$ to $+ 8 5^{\circ} C$ .
Humidity: 95% non-condensing, suitable for marine outdoor conditions.
Vibration & Shock: Designed to withstand marine vibration and shock (e.g., conforming to IEC 60945).
UV Resistance: Materials are UV-stabilized to prevent degradation from sun exposure.

Compliance:

Standards: Conforms to relevant international marine standards (e.g., IEC 60945 for environmental conditions, IEC 61108 series for GNSS receivers).