From: Gordon K. <go...@gu...> - 2006-05-04 16:32:36
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Hi, Sorry for the lag and the confusion. Here is our schematic for reference to compare against the u-blox datasheet. http://pubs.gumstix.com/boards/AUDIOSTIX/PCB00012-R791/PCB00012-R791_LEA.png It shows that we tied V_ANT (pin 19) to ground; i.e., hardwired for a passive antenna. To use an active antenna, one would need to put a 10R resistor in series from the active antenna power source, which can be an off-board source or internally generated by the adjacent VCC_RF pin 18. It sounds like we need a new (i.e.separate and clearly marked) product for active antennas. Is it adequate to use the internally generated VCC_RF, or would this **still** fall short of expectations-- i.e. we really need 2 new products? Gordon > Anderson, Steve N (Titan) @ TITAN escreveu: > >> The LEA-4H datasheet can be found at: >> http://www.u-blox.com/customersupport/Data_Sheets/LEA-4H_Data_Sheet(GPS. >> G4-MS4-05019).pdf >> But, in order to gain access to any of ublox technical documentation, >> you must first register at: >> http://www.u-blox.com/register.html >> >> >> > > > Thanks! Looks like it lacked details, but the required information can > be found on the sections 4.3.2 and 4.3.3 of this manual: > > http://www.u-blox.com/customersupport/gps.g4/ANTARIS4_Mdoules_SIM(GPS.G4-MS4-05007).pdf > > > I just read it and seems to me my analisys is correct: if v_ant is not > used it should be grounded, on which case active antennas will not be > powered. > > On another module I have, I could make some of them works (poorly) > without power, but I believe not all of them will behave like this, > because the internal amplifier will be shutdown and showing a very > high impendance between the antenna element and the cable. > > Most antennas sold out there are active ones. Very good passive > antennas can be an option when the cable is no longer than 10cm, but > they sometimes seems to be more susceptible to general noise (active > antennas are more susceptible to jamming noise, i.e. noise on the > exact gps frequencies) and to cable size/quality. > > Alexandre > > > ------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job > easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |