[gpsd-dev] SiRF IV protocol incompatibility?

[Eric S. Raymond]

From

http://elinux.org/RaspberryPiBoardVerifiedPeripherals#USB_GPS_devices

we have the the following hint of trouble (h/t Baylink):

    GlobalSat BU-353-S4 supports two protocols: NMEA, and SiRF v4. NMEA
    works fine, but SiRF v4 isn't compatible with "gpsd"'s SiRF v3
    interpreter, resulting in a greatly reduced data rate (as low as four
    location fixes per hour). To keep gpsd's autoconfiguration from
    putting the receiver in SiRF mode, you'll need to pass the "-b" flag
    when starting gpsd.

Well, that sucks.  Can anyone confirm that SiRFv4 binary protocol is
incompatible with v2 and v3?  Has anyone got a SirfStar IV device to
test with? If this is a real problem it's a pre-3.10 issue.

We could work around this by disabling the SiRF binary driver
entirely and treating an arriving SiRF binary packet as an instruction
to flip the device back to NMEA mode.  At this point our internal
interpolation and error modeling is good enough that this wouldn't 
be a functional loss.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

What if you were an idiot, and what if you were a member of Congress?
But I repeat myself.        -- Mark Twain