I have an MTK-3301 (Surefilre), running for about 10 years, on a Linux x64.
gpsd: 3.24.1~dev (revision release-3.24-295-g327b57968)
had stopped showing the Skymap. I assumed that this was a PHP or something error, and never got round to debugging it.
I did notice that if I pressed Refresh, etc, I would get flashes (once in a dozen times) of the Skymap.
Today, I re-read on the ?WATCH command, and noticed the GPGSV was appearing only every 5 cycles. So this behaviour is understandable.
Would it be better for gpsd.php to *not* clear the skymap on each cycle? Or might that give false, stale, results?
Alternatively, drivers/drivers.c, lines 1027ff:
NMEA_SEN_GLL, GPGLL interval - Geographic Position - Latitude longitude
NMEA_SEN_RMC, GPRMC interval - Recommended Minimum Specific GNSS Sentence
NMEA_SEN_VTG, GPVTG interval - Course Over Ground and Ground Speed
NMEA_SEN_GGA, GPGGA interval - GPS Fix Data
NMEA_SEN_GSA, GPGSA interval - GNSS DOPS and Active Satellites
NMEA_SEN_GSV, GPGSV interval - GNSS Satellites in View
NMEA_SEN_GRS, GPGRS interval - GNSS Range Residuals
NMEA_SEN_GST, GPGST interval - GNSS Pseudorange Errors Statistics
NMEA_SEN_MALM, PMTKALM interval - GPS almanac information
NMEA_SEN_MEPH, PMTKEPH interval - GPS ephemeris information
NMEA_SEN_MDGP, PMTKDGP interval - GPS differential correction information
NMEA_SEN_MDBG, PMTKDBG interval – MTK debug information
NMEA_SEN_ZDA, GPZDA interval - Time & Date
NMEA_SEN_MCHN, PMTKCHN interval – GPS channel status
// MTK 3333
NMEA_SEN_DTM, GPDTM interval - Datum reference
I see the "5" there clearly.
I tried using gpsctl, to send:
but that does not change anything