Hot!GPS Data

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huttojb
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2017/08/12 06:32:29 (permalink)
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GPS Data

All
 
This is not exactly about a PIC (yet) but it will be as soon as I get some GPS Data.
 
I purchased a GPS Module which I connected to Hyper Terminal and it seem to work.  I was getting the GPGGA, GPGSA etc headers but no data.  after leaving my laptop outside (On top of the shed roof) for about an hour I still had no vaid data within the strings.
 
I then purchased another GPS Module, thinking I had a "bad" module and not remembering where exactly I purchased from.  The new module has now arived and I'm getting the same results.... it must be something I'm doing wrong.
 
$GPRMC,,V,,,,,,,,,,N*53
$GPVTG,,,,,,,,,N*30
$GPGGA,,,,,,0,00,99.99,,,,,,*48
$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30
$GPGSV,1,1,00*79
$GPGLL,,,,,,V,N*64
$GPRMC,,V,,,,,,,,,,N*53
$GPVTG,,,,,,,,,N*30
$GPGGA,,,,,,0,00,99.99,,,,,,*48
$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30
$GPGSV,1,1,00*79
$GPGLL,,,,,,V,N*64

 
The data I'm receiving is about but it's not fixing on any satelites?  Does anyone know why?
 
Jason
#1

29 Replies Related Threads

    MBedder
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    Re: GPS Data 2017/08/12 06:47:21 (permalink)
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    Which module? Which antenna?
    #2
    huttojb
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    Re: GPS Data 2017/08/12 07:42:42 (permalink)
    +1 (1)
    This one NEO-6M and antenna marking G146

    Last one
    ROYAL TEK and no antenna marking.

    The last one is called Mini Locator from the itead website.

    The new one is from eBay.
    #3
    huttojb
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    Re: GPS Data 2017/08/12 07:52:40 (permalink)
    +1 (1)
    I have just found this info on the net.

    The Neo 6M takes a bit of time to fix when first powered on. If your board is fitted with a small battery it will most probably be flat and will take an hour or two to charge up. It is there to provide charge to the EEPROM and the onboard RTC.

    You do not get a valid data sentence out of the GPS until the RTC can sync time.

    So mine does have a small battery, been on for an hour now so I'll wait a little longer. Then go back outside (wonder what my neighbours think)

    Jason.
    post edited by huttojb - 2017/08/12 07:53:51
    #4
    MBedder
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    Re: GPS Data 2017/08/12 08:26:56 (permalink)
    +1 (1)
    The Neo 6M without additional external components can work only with passive antenna since it doesn't supply voltage to power the active antena (see the LEA-6/NEO-6/MAX-6 Hardware Integration Manual for details). So if your antenna is active (i.e. contains internal amplifier IC) you will never get valid GPS data. The Mini Locator should work with either active or passive antenna.
    #5
    huttojb
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    Re: GPS Data 2017/08/12 08:37:00 (permalink)
    +1 (1)
    I brought both as a module with the antenna supplied. Already on the PCB with pin outs for VCC, GRD, RX, TX AND PPS.

    The antenna on the NEO is a small block, about 10mm by 4mm.

    I thought it would work as supplied.

    Jason.
    #6
    huttojb
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    Re: GPS Data 2017/08/12 08:44:08 (permalink)
    +1 (1)
    https://trademe.tmcdn.co.nz/photoserver/tq/564937760.jpg

     
    New one
     
    Previous One
    https://www.itead.cc/mini-locator.html

     
    #7
    MBedder
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    Re: GPS Data 2017/08/12 09:14:18 (permalink)
    +1 (1)
    The small antenna which comes with NEO is a passive antenna, and the one of Locator is active. But in any case if the schematics of Locator is implemented on the PCB it will not work at all because the RF signal from antenna in completely blocked by C6 and C7 100nF capacitors. Check your PCB and remove these capacitors if they are mounted (I can see on the zoomed photo that they are).
    #8
    MBedder
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    Re: GPS Data 2017/08/12 09:15:40 (permalink)
    +1 (1)
    huttojbI thought it would work as supplied.
    It would but not should LoL


    #9
    huttojb
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    Re: GPS Data 2017/08/12 10:17:35 (permalink)
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    I have removed the Cap's as you have suggested..  and currently sitting in my garden ......
     
     
    #10
    huttojb
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    Re: GPS Data 2017/08/12 10:31:16 (permalink)
    +1 (1)
    Whoop Woo.... (Well sort of)
     
    Getting data as expected.  Thank you, but why am I about 1/2 mile off my location on GPS Data
     
     
    $GNZDA,172900.000,12,08,2017,,*4A
    $GPGGA,172900.000,5227.4358,N,00158.4871,W,1,06,3.0,178.9,M,48.2,M,,0000*41
    $GNGSA,A,3,19,03,22,17,14,01,,,,,,,5.3,3.0,4.4*20
    $GPGSV,4,1,15,19,35,306,29,03,81,243,28,22,70,077,26,17,50,282,23*74
    $GPGSV,4,2,15,14,25,046,18,01,59,119,15,04,72,282,,11,37,146,*7C
    $GPGSV,4,3,15,23,30,180,,31,14,077,,32,09,037,,06,09,296,*78
    $GPGSV,4,4,15,09,05,196,,12,04,353,,28,03,241,*43
    $GLGSV,3,1,10,81,56,310,,88,56,083,,65,54,103,,72,27,034,*61
    $GLGSV,3,2,10,80,25,322,,79,24,264,,66,22,167,,87,08,102,*65
    $GLGSV,3,3,10,82,06,290,,73,01,005,*63
    $GNRMC,172900.000,A,5227.4358,N,00158.4871,W,0.00,10.78,120817,,,A*52

    #11
    huttojb
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    Re: GPS Data 2017/08/12 10:36:53 (permalink)
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    MBedder
    The small antenna which comes with NEO is a passive antenna, and the one of Locator is active. But in any case if the schematics of Locator is implemented on the PCB it will not work at all because the RF signal from antenna in completely blocked by C6 and C7 100nF capacitors. Check your PCB and remove these capacitors if they are mounted (I can see on the zoomed photo that they are).




    Thank you so much - now I'm going to write an angry email to Ited..  Just need to understand why my locations off?
     
    Is there any reason why the other one isn't working?
     
    Jason
    #12
    MBedder
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    Re: GPS Data 2017/08/12 11:19:12 (permalink)
    +1 (1)
    The position should become more accurate when the receiver finishes collecting some additional data - so called ephemeris and ionosphere. For the first cold start it can take up to several hours depending on the satellites' signal strength, S/N ratio, number of visible satellites, constellation geometry and many other factors.
     
    To keep this collected data ready for a next start you must supply and connect a backup battery as shown on Page 5 of the RoyalTek REB-5216 Operational Manual (but NOT as shown on the Locator schematics supplied by Itead - in their case the battery can easily explode since there is no current limiting resistor on the PCB). The same applies to the NEO module, and its schematics also needs to be revised to avoid the issues similar to Locator.
     
    Another possible issue with the NEO module could be its small passive antenna which doesn't provide enough signal level to the receiver. Try relocating your position to some open space because even the trees in and around your garden can dramatically reduce the satellites' signals.
    #13
    huttojb
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    Re: GPS Data 2017/08/12 11:28:20 (permalink)
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    MBedder
    The position should become more accurate when the receiver finishes collecting some additional data - so called ephemeris and ionosphere. For the first cold start it can take up to several hours depending on the satellites' signal strength, S/N ratio, number of visible satellites, constellation geometry and many other factors. To keep this collected data ready for a next start you must supply and connect a backup battery as shown on Page 5 of the RoyalTek REB-5216 Operational Manual (but NOT as shown on the Locator schematics supplied by Itead - in their case the battery can easily explode since there is no current limiting resistor on the PCB). The same applies to the NEO module, and its schematics also needs to be revised to avoid the issues similar to Locator. Another possible issue with the NEO module could be its small passive antenna which doesn't provide enough signal level to the receiver. Try relocating your position to some open space because even the trees in and around your garden can dramatically reduce the satellites' signals.



    Thank you. I'll leave the module on for a few hours and see if it becomes more accurate then. At least I know where to come for any GPS information. Lol.

    Thank you very much for your time.
    #14
    CinziaG
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    Re: GPS Data 2017/08/12 12:09:25 (permalink)
    +1 (1)
    It could (could!) also be a matter of decimal vs. sessagesimal (ie. "60s") grad and tenth of grad use. At least, it did hurt me at the beginning Smile
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    rodims
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    Re: GPS Data 2017/08/12 12:23:22 (permalink)
    +1 (1)
    I assume your are still outside, and keep the module/antenna not too close to your Laptop. 
    (Edit: the number of sats is 15. The following is wrong)
    You have / had 4 satellites in view  (first number)
    $GPGSV,4,1,15,19,35,306,29,03,81,243,28,22,70,077,26,17,50,282,23*74
    $GPGSV,4,2,15,14,25,046,18,01,59,119,15,04,72,282,,11,37,146,*7C
    $GPGSV,4,3,15,23,30,180,,31,14,077,,32,09,037,,06,09,296,*78
    $GPGSV,4,4,15,09,05,196,,12,04,353,,28,03,241,*43
    This is enough to get a fix (which you obviously have), but should improve. Keep an eye on the number. As mbedder wrote I would expect the number (and thus also precision) to increase over the time. http://www.trakgps.com/en...mation/65-gps-accuracy
    post edited by rodims - 2017/08/13 01:26:21
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    huttojb
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    Re: GPS Data 2017/08/12 12:31:46 (permalink)
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    rodims
    I assume your are still outside, and keep the module/antenna not too close to your Laptop.
     
    You have / had 4 satellites in view  (first number)
    $GPGSV,4,1,15,19,35,306,29,03,81,243,28,22,70,077,26,17,50,282,23*74
    $GPGSV,4,2,15,14,25,046,18,01,59,119,15,04,72,282,,11,37,146,*7C
    $GPGSV,4,3,15,23,30,180,,31,14,077,,32,09,037,,06,09,296,*78
    $GPGSV,4,4,15,09,05,196,,12,04,353,,28,03,241,*43

    This is enough to get a fix (which you obviously have), but should improve. Keep an eye on the number. As mbedder wrote I would expect the number (and thus also precision) to increase over the time.
     
    http://www.trakgps.com/en...mation/65-gps-accuracy




    Thanks Rodims.
    I was under the impression that the sat in view was 15. According to the NMEA Datra
     
    GPGSV,4,1,15,19,35,306,29,03,81,243,28,22,70,077,26,17,50,282,23*74

    #17
    MBedder
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    Re: GPS Data 2017/08/12 12:58:02 (permalink)
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    CinziaGIt could (could!) also be a matter of decimal vs. sessagesimal (ie. "60s") grad and tenth of grad use. At least, it did hurt me at the beginning
    No tenth of grad but decimal fractions of min - as explained here: http://www.gpsinformation.org/dale/nmea.htm#GGA


    #18
    MBedder
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    Re: GPS Data 2017/08/12 13:25:52 (permalink)
    +1 (1)
    rodimsYou have / had 4 satellites in view  (first number)
    $GPGSV,4,1,15,19,35,306,29,03,81,243,28,22,70,077,26,17,50,282,23*74
    $GPGSV,4,2,15,14,25,046,18,01,59,119,15,04,72,282,,11,37,146,*7C
    $GPGSV,4,3,15,23,30,180,,31,14,077,,32,09,037,,06,09,296,*78
    $GPGSV,4,4,15,09,05,196,,12,04,353,,28,03,241,*43
    Wrong. The first data field ("4") means there are 4 GSV sentences in succession, the next field is a GSV sentence number (note 1,2,3,4) because every single GSV sentence can contain data of only four satellites (SV) maximum.
     
     
    The next field ("15") is a number of visible GPS+GLONASS SVs and the next groups of four fields are the SV number, its elevation, its azimuth and its S/N ratio - up to four SV groups in a single sentence. See the link in my message above.
    post edited by MBedder - 2017/08/12 13:28:37
    #19
    huttojb
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    Re: GPS Data 2017/08/12 13:36:17 (permalink)
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    MBedder
    rodimsYou have / had 4 satellites in view  (first number)
    $GPGSV,4,1,15,19,35,306,29,03,81,243,28,22,70,077,26,17,50,282,23*74
    $GPGSV,4,2,15,14,25,046,18,01,59,119,15,04,72,282,,11,37,146,*7C
    $GPGSV,4,3,15,23,30,180,,31,14,077,,32,09,037,,06,09,296,*78
    $GPGSV,4,4,15,09,05,196,,12,04,353,,28,03,241,*43
    Wrong. The first data field ("4") means there are 4 GSV sentences in succession, the next field is a GSV sentence number (note 1,2,3,4) because every single GSV sentence can contain data of only four satellites (SV) maximum.
     
     
    The next field ("15") is a number of visible GPS+GLONASS SVs and the next groups of four fields are the SV number, its elevation, its azimuth and its S/N ratio - up to four SV groups in a single sentence. See the link in my message above.


    So is 15 the number of Satellites, I'm not sure what "("15") is a number of visible GPS+GLONASS SVs" actually means.
     
    Also, as your so knowledgable on GPS (it looks like you have done all this before) how do you see Satellite Signal Strength.  I've seen on Screen Shots, devices where it shows the signal of each satellite.  I cannot see with the data I receive where I could establish that information.
     
    To share information - I have found a great excel document which can be downloaded from here that shows alot of information converstion
     
    http://gpsworld.com/what-exactly-is-gps-nmea-data/

     
    Jason
    #20
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