AboutLuis Emiliani Expertise Strengths
- Satellite link design and analysis
- Vsat network design and analysis
- Propagation aspects for terrestrial and satellite links
- ITU-R P recommendations
Can not help with:
- Questions related to TV receivers, TV kits, or specific networks such as DirecTV or DISH
- Antenna pattern synthesis, RF MoM analysis, S-parameters.
Experience My experience is in satellite communication networks and terrestrial microwave links.
Question QUESTION: Hello. i was wondering why does a gps need a satellite to tell you where you are. why cant they just program the system where it is at a given moment and from there on it should make its calculations thru the manuvers from the car. for eg. if the car driver a mile and then makes a right so the system should reflect that on the map. we have very detailed maps so we can rely on them. this way it would be much cheaper and faster results.
ANSWER: Hi,
the satellite positioning systems uses actually more than one satellite to determine your position. in essence, the system uses a series of pulses transmitted by the satellites (it needs at least 3 to determine the position) and by means of the differential delays between the moment each pulse is received with respect to another, and by knowing where the satellite is in its orbit, the receiver can determine where it is on the earth with a precision around 10 or 100 meters depending on the quality of the receiver and what enhancements it has.
the system you proposed would translate the intelligence of the positioning to the car. i am not sure it would be cheaper, because you are now asking the car to track how far it has moved from a single point and that can be done by counting revolutions of the wheels, and to keep track of where he turned to follow on a maps. you have provide him with an indication of course of where you are going in relation to the map, as for instance how is the car going to know where he is when you turn the system on (are you thinking about an infinite memory of past positions so he keeps track of where he is?) and on which direction you are moving? what does left turn means in relation to the map?
i believe it is not as simple as you initially propose. and that is where the ease of knowing your coordinates comes very handy. the gps system does not know where you are going but after a couple of measurements it will tell you the direction in which you are moving.
i hope this highlights the issues involved in your idea. you can find much more about GPS and positioning systems by reading the forums around how satellite navigators operate.
regards
luis
---------- FOLLOW-UP ----------
QUESTION: I would assume that with today tech. the movement from the car should be able to record where it is going. And the same goes as to which direction it is going, since it should know if you are going foward or reverse. And just like Auto shops could align the wheels, the same could apply to this, that there would be a service to align your GPS if it got messed up. Or they could put in the system so that you can align it by yourself.
Answer Hi,
well, i do not think technology is an obstacle. the question is how much it will cost to put a dedicated system in place in each car. in the end it might very well be more expensive than you buying a standard gps receiver. a bluetooth based gps receiver like those you can use with laptops and cell phones can go for around 25 dollars on ebay...
In any case, that would no longer be a GPS system, as you are not relying in the satellites to give you a position. you would definitely need an internal compass to let the system know if you are going north or south, east or west...
I do not think it is not feasible, what i think is that it would add another layer of complexity to the problem, and nothing a-priori tells you it won't be more expensive.
