Multiple TPV lines per sec?

[Tor Rune Skoglund]

Hi List,

wonder if someone has a hint on this....:

Sometimes, we get multiple TPV lines per seconds from gpsd, e.g. using 
gpspipe. After restarting gpsd, one of the lines go away.

For example:

~ $ gpspipe -w | grep TPV
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:13.000Z","ept":0.005,"lat":63.448694233,"lon":10.902940283,"altHAE":47.800,"altMSL":7.800,"alt":7.800,"epx":7.923,"epy":9.524,"epv":20.700,"magvar":3.9,"speed":18.892,"climb":-0.300,"epd":53.5054,"eps":19.05,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:13.000Z","ept":0.005,"lat":63.448694233,"lon":10.902940283,"altHAE":47.800,"altMSL":7.800,"alt":7.800,"epx":7.923,"epy":9.524,"epv":20.700,"track":239.6000,"magtrack":239.6000,"magvar":3.9,"speed":18.932,"climb":-0.300,"epd":53.5054,"eps":19.05,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:14.000Z","ept":0.005,"lat":63.448610817,"lon":10.902599367,"altHAE":48.000,"altMSL":8.000,"alt":8.000,"epx":7.923,"epy":9.524,"epv":20.700,"magvar":3.9,"speed":19.385,"climb":0.200,"epd":52.3279,"eps":19.05,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:14.000Z","ept":0.005,"lat":63.448610817,"lon":10.902599367,"altHAE":48.000,"altMSL":8.000,"alt":8.000,"epx":7.923,"epy":9.524,"epv":20.700,"track":241.1000,"magtrack":241.1000,"magvar":3.9,"speed":19.292,"climb":0.200,"epd":52.3279,"eps":19.05,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}
^C
 ~ $ sudo /etc/init.d/gpsd restart
 * Stopping gpsd ... [ ok ]
 * Starting gpsd ... [ ok ]
remotelogin@platform ~ $ gpspipe -w | grep TPV
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:36.000Z","ept":0.005,"lat":63.447143167,"lon":10.894161967,"altHAE":45.500,"altMSL":5.500,"alt":5.500,"epx":7.993,"epy":10.220,"epv":20.700,"track":247.4000,"magtrack":247.4000,"magvar":3.9,"speed":20.886,"climb":-0.100,"epd":51.8753,"eps":20.44,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:37.000Z","ept":0.005,"lat":63.447074950,"lon":10.893788317,"altHAE":45.400,"altMSL":5.400,"alt":5.400,"epx":7.993,"epy":10.220,"epv":20.700,"track":247.2000,"magtrack":247.2000,"magvar":3.9,"speed":20.681,"climb":-0.100,"epd":53.8221,"eps":20.44,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}
{"class":"TPV","device":"/dev/gpsUSB.1.5","mode":3,"time":"2021-01-27T09:52:38.000Z","ept":0.005,"lat":63.447001017,"lon":10.893401283,"altHAE":45.200,"altMSL":5.200,"alt":5.200,"epx":7.993,"epy":10.220,"epv":20.700,"track":246.8000,"magtrack":246.8000,"magvar":3.9,"speed":20.475,"climb":-0.200,"epd":51.9080,"eps":20.44,"epc":41.40,"geoidSep":40.000,"eph":15.200,"sep":22.800}


We done some tests, but have not reached a good conclusion yet apart 
from it helps if we delay starting/restarting gpsd too soon during boot 
or after a new GNSS device has been added to the system.

Any quick, initial pointers and ideas on under which circumstances gpsd 
=> gpspipe would report more than one TPV message per sec would be 
appreciated.

BR,
Tor Rune Skoglund, trs@fourc.eu