The GPS 24xd GNSS receiver is capable of receiving four different global navigation system constellations:
- US Air Force NAVSTAR GPS
- European Union GALILEO
- Russian GLONASS
- Republic of China BEIDOU
In addition to jumping ahead of the pack with four constellations, the GPS 24xd also supports both L1 and L5 frequencies on GPS (and possibly GLONASS and others when available). The L1 C/A (Coarse Acquisition) signals are the ones that have been in civilian use since the earliest days of GPS. The L5 signals are newly added civilian signals available from GPS. The L5 signals have been available from the GPS constellation beginning with the GPS IIF in May 2010, but until now very few (if any) recreational grade marine GPS could receive them.
The L5 signals should have a stronger signal (by about 1.5 dB). Another advantage of L5 is decreased doppler shift of the chip frequency. (This is a rather complex technical topic. For explanation see a separate article published elsewhere.)
The most significant advantage to being able to receive both L1 and L5 signals from the same satellite is the ability to estimate and compensate for ionospheric delay. Variation in ionosphere delay introduces errors in the position solution. Along with spaced-based augmentation systems (SBAS such as WAAS), compensation of ionospheric delay allows an improvement in the accuracy of the position solution to a level where the CEP (Circular Error Probability) will be not more than 1-meter for 88-percent of the time.
GARMIN did not stop there. They have also included a magnetic heading sensor that is said to have an accuracy of ± 3 degrees.
In addition to the technology step forward, the GPS 24xd is a NMEA-2000 device that can be powered by the network (Load Equivalent Number =3), and a 6-meter drop cable and network T-connector are included. It also outputs NMEA-0183 sentences. A pole-mount adaptor, a surface mount adapter, and an under deck mount adaptor are included. The retail price is $299.99.
The GARMIN website page for the GPS 24xd is located at https://buy.garmin.com/en-US/US/p/684270
The GARMIN Press Release can be found at https://www.businesswire.com/news/home/20201015005340/en/