China Coast Guard and Patrol vessels
- Thread starter crobato
- Start date
Geographer
Junior Member
I've read that the spheres behind the tower on the bridge are for satellite navigation. Is that correct? If so, why are they so big when commercial satellite navigation receivers are small enough to fit into a phone?
I think it is for satellite communication if it has anything to do with satellite.
plawolf
Lieutenant General
Most civilian mobile phone GPS are not true GPS. They rely mostly on the mobile relay towers on the ground near them for their GPS functionality (why GPS typically doesn't work when phones have no mobile signal).
Any true satellite mobile phone is instantly recognisable from conventional mobile phones from the massive additional receiver they need to pick up satellite signals directly.
As a general rule of thumb, the bigger the receiver, the weaker a signal it can pick up.
True satellite phones can get very choppy and cut out if there is bad weather.
Storms can get far more server out in the open oceans compared to on land, and it's during such times that you will need you satellite navigation to work flawlessly the most.
Something else to factor in is the fact that unlike land vehicles, naval ships can pitch quite heavily during rough seas. As such, it is beneficial to have a much bigger antenna such that even when the ship is pitching heavily, enough of the antenna still has direct line of sight to enough of the sky to have a good chance of picking up GPS signals to avoid loosing contact.
That is why naval GPS antennas typically are beefier than for land based versions.
joshuatree
Captain
Don't think this pic was posted before, being reported as new CG hulls (class 818) that are derived from the 054 hull.
joshuatree
Captain
2901 in Sanya.
Sorry about my typing!
joshuatree
Captain
Do folks think these 054 based CG hulls are exactly identical to the 054(A)(A+)s to leverage economies of scale? Or is it still cheaper to build them to lower non-military spec? I guess the same question can be asked of the 056 derived CG vessels.