On a sunny day (Mon, 17 Sep 2012 01:13:57 -0500) it happened G. Morgan <sealteam6@osama-is-dead.net> wrote in <esfd58hsns3727pn34nu30hqss93dn4j36@Osama-is-dead.net>:>Jan Panteltje wrote: > >>Google for example: >> IS-GPS-800B.pdf >>for a lot of technical details. > > >I didn't understand a damn thing in that document!Yes, it presumes some prior knowledge try this website, the guy build his own GPS stuff, and does a good job at designing too: A homemade receiver for GPS & GLONASS satellites http://www.s5tech.net/s53mv/navsats/theory.html
signal strength on a GPS
Started by ●September 15, 2012
Reply by ●September 17, 20122012-09-17
Reply by ●September 17, 20122012-09-17
On a sunny day (Mon, 17 Sep 2012 01:15:15 -0500) it happened G. Morgan <sealteam6@osama-is-dead.net> wrote in <iufd585m2mbdg0gnf48nu88jbrdcpklm8s@Osama-is-dead.net>:>Jan Panteltje wrote: > >>No, you misunderstand the GPS system. >>The satellites all transmit at the same frequency, their digital signals are >>xored before modulation with a pseudo random code, a so called 'Gold code'. >>This code is different for each satellite. >>Basically this is done with a shift register. >>In the receiver AFTER demodulation the digital signal is run through a similar >>shift register, and one by one tested for the correct Gold code (each sat has its own code). >>In case of noise, you do not get an exact match against the know codes, and the number of wrong >>bits is then a measure for the signal to noise ratio. >>100% good signal, no bit errors. >>Weak signal lots of bit errors. >> http://en.wikipedia.org/wiki/GPS_signals > > >Do they x-mit a different freq. for military use?There are in fact several signals on diffrent frequencies, read the spec.
Reply by ●September 17, 20122012-09-17
On a sunny day (Mon, 17 Sep 2012 08:30:48 +0300) it happened upsidedown@downunder.com wrote in <u3cd58dg8egllr6lgbsa0en02rflm791jc@4ax.com>:>On Sun, 16 Sep 2012 18:45:35 GMT, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: > >>>>Probably signal to noise ratio, in fact bit error rate. >>>>In GPS (the US system) all sats transmit at the same frequency, >>>>their data xored with some pseudo random code that is different for each sat. >>> >>>If you use a 4-quadrant (Gilbert cell) multiplier (mixer) instead of a >>>XOR gate, the despread signal will definitely have a positive SNR in >>>the 1000/50 Hz bandwidth) and the absolute signal power should be >>>easily measurable. >> >>No, you misunderstand the GPS system. >>The satellites all transmit at the same frequency, their digital signals are >>xored before modulation with a pseudo random code, a so called 'Gold code'. >>This code is different for each satellite. >>Basically this is done with a shift register. >>In the receiver AFTER demodulation the digital signal is run through a similar >>shift register, and one by one tested for the correct Gold code (each sat has its own code). >>In case of noise, you do not get an exact match against the know codes, and the number of wrong >>bits is then a measure for the signal to noise ratio. >>100% good signal, no bit errors. >>Weak signal lots of bit errors. >> http://en.wikipedia.org/wiki/GPS_signals > >The GPS signal is an ordinary direct sequence spread spectrum (DSSS) >signal. It can be received with a mixer/multiplier/xor gate by >multiplying the received signal with the same chip clock (in this case >1.023 MHz satellite specific PRN sequence) _synchronized_ with the >transmitter modulator chip clock. After the demodulator the about 1 >MHz wide spread spectrum signal is despread to something about 1 kHz. >At this point you could also make power measurements. After this, the >50 bit/s data signal is extracted. > >The shift register and bit error detection you are talking about has >to do with signal acquisition _before_ the receiver chip clock >generator has been synchronized with the transmitter chip clock.Partly, as you want to display signal to noise for each individual satellite, you have to identify the satellite in the signal. For that to happen you need to detet its Gold code directly. Now you are full circle :-)
Reply by ●September 17, 20122012-09-17
Jan Panteltje wrote:>On a sunny day (Mon, 17 Sep 2012 01:13:57 -0500) it happened G. Morgan ><sealteam6@osama-is-dead.net> wrote in ><esfd58hsns3727pn34nu30hqss93dn4j36@Osama-is-dead.net>: > >>Jan Panteltje wrote: >> >>>Google for example: >>> IS-GPS-800B.pdf >>>for a lot of technical details. >> >> >>I didn't understand a damn thing in that document! > >Yes, it presumes some prior knowledge >try this website, the guy build his own GPS stuff, and does a good job at designing too: > >A homemade receiver for GPS & GLONASS satellites > http://www.s5tech.net/s53mv/navsats/theory.htmlThanks.
Reply by ●September 17, 20122012-09-17
On 9/16/2012 11:36 AM, John Larkin wrote:> On Sat, 15 Sep 2012 22:17:57 -0700, MrTallyman > <MrTallyman@BananaCountersRUs.org> wrote: > >> On Sat, 15 Sep 2012 20:02:34 -0700, John Larkin >> <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Sun, 16 Sep 2012 00:03:50 +0000 (UTC), Jim Whitby >>> <james@jameswhitby.org> wrote: >>> >>>> I'm asking this here in the hope someone knows something about GPS >>>> receivers. >>>> >>>> I'm a decent tech, but not an engineer... >>>> >>>> I have a Tomtom 2535 gps. Nice unit blah blah. >>>> >>>> Some ( software? ) engineer decided to change the gps info display. It >>>> now contains a pic of earth with dots for satellites instead of a bar >>>> graph. Ok. No biggie. >>> >>> A software engineer probably doesn't know what a dB is. >> >> You're an idiot. > > OK, explain to us what a dB is.If you don't know, why should we tell you. Rick
Reply by ●September 17, 20122012-09-17
On Mon, 17 Sep 2012 08:01:03 GMT, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:>On a sunny day (Mon, 17 Sep 2012 08:30:48 +0300) it happened >upsidedown@downunder.com wrote in ><u3cd58dg8egllr6lgbsa0en02rflm791jc@4ax.com>: > >>On Sun, 16 Sep 2012 18:45:35 GMT, Jan Panteltje >><pNaonStpealmtje@yahoo.com> wrote: >> >>>>>Probably signal to noise ratio, in fact bit error rate. >>>>>In GPS (the US system) all sats transmit at the same frequency, >>>>>their data xored with some pseudo random code that is different for each sat. >>>> >>>>If you use a 4-quadrant (Gilbert cell) multiplier (mixer) instead of a >>>>XOR gate, the despread signal will definitely have a positive SNR in >>>>the 1000/50 Hz bandwidth) and the absolute signal power should be >>>>easily measurable. >>> >>>No, you misunderstand the GPS system. >>>The satellites all transmit at the same frequency, their digital signals are >>>xored before modulation with a pseudo random code, a so called 'Gold code'. >>>This code is different for each satellite. >>>Basically this is done with a shift register. >>>In the receiver AFTER demodulation the digital signal is run through a similar >>>shift register, and one by one tested for the correct Gold code (each sat has its own code). >>>In case of noise, you do not get an exact match against the know codes, and the number of wrong >>>bits is then a measure for the signal to noise ratio. >>>100% good signal, no bit errors. >>>Weak signal lots of bit errors. >>> http://en.wikipedia.org/wiki/GPS_signals >> >>The GPS signal is an ordinary direct sequence spread spectrum (DSSS) >>signal. It can be received with a mixer/multiplier/xor gate by >>multiplying the received signal with the same chip clock (in this case >>1.023 MHz satellite specific PRN sequence) _synchronized_ with the >>transmitter modulator chip clock. After the demodulator the about 1 >>MHz wide spread spectrum signal is despread to something about 1 kHz. >>At this point you could also make power measurements. After this, the >>50 bit/s data signal is extracted. >> >>The shift register and bit error detection you are talking about has >>to do with signal acquisition _before_ the receiver chip clock >>generator has been synchronized with the transmitter chip clock. > >Partly, >as you want to display signal to noise for each individual satellite, >you have to identify the satellite in the signal. >For that to happen you need to detet its Gold code directly. >Now you are full circle :-)So in reality, you need four independent signal strength signals for the best (geometry) four satellites
Reply by ●September 17, 20122012-09-17
On Mon, 17 Sep 2012 16:12:48 -0400, rickman <gnuarm@gmail.com> wrote:>On 9/16/2012 11:36 AM, John Larkin wrote: >> On Sat, 15 Sep 2012 22:17:57 -0700, MrTallyman >> <MrTallyman@BananaCountersRUs.org> wrote: >> >>> On Sat, 15 Sep 2012 20:02:34 -0700, John Larkin >>> <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>> On Sun, 16 Sep 2012 00:03:50 +0000 (UTC), Jim Whitby >>>> <james@jameswhitby.org> wrote: >>>> >>>>> I'm asking this here in the hope someone knows something about GPS >>>>> receivers. >>>>> >>>>> I'm a decent tech, but not an engineer... >>>>> >>>>> I have a Tomtom 2535 gps. Nice unit blah blah. >>>>> >>>>> Some ( software? ) engineer decided to change the gps info display. It >>>>> now contains a pic of earth with dots for satellites instead of a bar >>>>> graph. Ok. No biggie. >>>> >>>> A software engineer probably doesn't know what a dB is. >>> >>> You're an idiot. >> >> OK, explain to us what a dB is. > >If you don't know, why should we tell you.You two do make quite a pair.
Reply by ●September 18, 20122012-09-18
On a sunny day (Mon, 17 Sep 2012 23:42:23 +0300) it happened upsidedown@downunder.com wrote in <ci2f58t5mbaljorvassqg3j52s1nmiihp3@4ax.com>:>So in reality, you need four independent signal strength signals for >the best (geometry) four satellites? You need 3 sats for a 2D position, and 4 sats for a 3D position solution.
Reply by ●September 18, 20122012-09-18
On Sun, 16 Sep 2012 08:36:33 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>On Sat, 15 Sep 2012 22:17:57 -0700, MrTallyman ><MrTallyman@BananaCountersRUs.org> wrote: > >>On Sat, 15 Sep 2012 20:02:34 -0700, John Larkin >><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Sun, 16 Sep 2012 00:03:50 +0000 (UTC), Jim Whitby >>><james@jameswhitby.org> wrote: >>> >>>>I'm asking this here in the hope someone knows something about GPS >>>>receivers. >>>> >>>>I'm a decent tech, but not an engineer... >>>> >>>>I have a Tomtom 2535 gps. Nice unit blah blah. >>>> >>>>Some ( software? ) engineer decided to change the gps info display. It >>>>now contains a pic of earth with dots for satellites instead of a bar >>>>graph. Ok. No biggie. >>> >>>A software engineer probably doesn't know what a dB is. >> >> You're an idiot. > >OK, explain to us what a dB is.How would a toilet cleaner know that?
Reply by ●September 18, 20122012-09-18
On Tue, 18 Sep 2012 10:18:50 +0100, Pomegranate Bastard <pommyB@dsl.pipex.com> wrote:>On Sun, 16 Sep 2012 08:36:33 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>On Sat, 15 Sep 2012 22:17:57 -0700, MrTallyman >><MrTallyman@BananaCountersRUs.org> wrote: >> >>>On Sat, 15 Sep 2012 20:02:34 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Sun, 16 Sep 2012 00:03:50 +0000 (UTC), Jim Whitby >>>><james@jameswhitby.org> wrote: >>>> >>>>>I'm asking this here in the hope someone knows something about GPS >>>>>receivers. >>>>> >>>>>I'm a decent tech, but not an engineer... >>>>> >>>>>I have a Tomtom 2535 gps. Nice unit blah blah. >>>>> >>>>>Some ( software? ) engineer decided to change the gps info display. It >>>>>now contains a pic of earth with dots for satellites instead of a bar >>>>>graph. Ok. No biggie. >>>> >>>>A software engineer probably doesn't know what a dB is. >>> >>> You're an idiot. >> >>OK, explain to us what a dB is. > >How would a toilet cleaner know that?Try to tell us, since that is what *you* do for a living. As for myself... When I adjust the waveguide output channel of a high power satellite transceiver, my employer is quite comfortable with my understanding of logarithmic progression. Also when I adjust the noise source loop that we pump it with for the test. You are lost. As for you... When you adjust your mop head, be sure to bring it right up next to your face so your crabs and fleas can hop onto it and migrate to new horizons. Good job of spreading the vermin, you immature little retarded characterless honorless bastard. Go back to the kook group, dumbfuck.
