Seductive serendipity / Verleidende serendipiteit

April 19th, 2008

Motorola Oncore UT+ and LinuxPPS

oncore-ut.jpgRecently I bought a Motorola Oncore UT+ GPS timing receiver on Ebay. I run Debian Linux and it seems that the refclock_oncore driver is not included in ntpd because the LinuxPPSAPI from Rodolfo Giometti is not an official part of the linux kernel (yet? ; -)

I interfaced the module with three inverters (74HC14) to my RS232 port. The TX-line was leveled with two resistors and an universal diode (DUS). In my opinion complex interfaces like the TAC2 are not necessary.
(click on image to enlarge and see the details) or click here to download the schematic of my interface interpretation.

To get my UT+ to do work for ntpd, I needed to compile ntpd from source. Normally this is not an issue, but I did not manage to include the oncore refclock in the code and continuously obtained the error:

refclock_newpeer: clock type 30 invalid

in my ntpd logfiles.

With the help of the author of the Oncore driver, Reg Clemens, the following cookbook recipe crystallized, assuming that you have a working LinuxPPS system and a patched kernel(source):

  1. in /usr/include ln -s /usr/src/<linux-source>/Documentation/pps/timepps.h . <- ‘.’ !
  2. in /usr/include/sys ln -s /usr/src/<linux-source>/Documentation/pps/timepps.h . <- ‘.’ !
  3. verify that you also have the links to asm, asm-generic and linux, according to Rodolfo’s wiki
  4. in /dev ln -s pps0 oncore.pps.0 (or whatever ppsX you will use)
  5. in /dev ln -s ttyS0 oncore.serial.0 (or whatever interface you’ll use, ln -s ttyS2 oncore.serial.1 is also allowed e.g.)
  6. download the ntpd source from and untar it. I use the development version of ntp.
  7. configure with at least the options: ./configure –enable-ONCORE –enable-SHM
  8. verify from the output that there are ‘yesses’ after timepps.h and Motorola Oncore
  9. make
  10. add the following entry in ntp.conf: server (when you used oncore.pps.0 and oncore.serial.0)
  11. edit /etc/ntp.oncore.0:
    # Oncore UT+ configuration file
    # —– mandatory lines —————-
    MODE 1
    LON 5 11.4548 #insert your own longitude here
    LAT 52 14.2342 #insert your own lattitude here
    HT 11.0 M #insert your own GPS height here
    # —– optional lines ——————
    DELAY 20 NS #delay is approx 5 ns/m cable (I have 4m cable between my antenna and UT+
    CLEAR #negative edge is synced to UTC epochs (due to HC14 inverter, see above)
    SHMEM /var/log/ntpstats/oncore.0
    MASK 0
  12. kill all ntpd processes, go to the ntpd directory and start ntpd with root privs as ./ntpd
  13. verify in your ntpd logfile that ntpd picks up the Oncore driver:
    54571 82587.208 ONCORE DRIVER — CONFIGURING
    54571 82587.208 state = ONCORE_NO_IDEA
    54571 82587.225 Input mode = 1
    54571 82587.225 Initializing timeing to Clear..
    54571 82587.226 SHMEM (size = 3584) is CONFIGURED and available as /var/log/ntpstats/oncore.0
    54571 82587.226 state = ONCORE_CHECK_I
    *snip* and somewhat later…..
    54571 82588.542 This looks like an Oncore UT with version 3.1 firmware.
    54571 82588.542 Channels = 8, TRAIM = ON
    54571 82588.542 state = ONCORE_CHECK_CHAN
    54571 82593.151 Input says chan = -1
    54571 82593.151 Model # says chan = 8
    54571 82593.151 Testing says chan = 8
    54571 82593.151 Using chan = 8
    54571 82593.151 state = ONCORE_HAVE_CHAN
    54571 82594.641 state = ONCORE_TEST_SENT
    54571 82603.241 GPS antenna: OK
    54571 82603.241 state = ONCORE_INIT
    54571 82604.701 Setting Posn from input data
    54571 82604.701 state = ONCORE_ALMANAC
    *snip* and somewhat later……
    54571 82606.941 Cable delay is set to 20 ns
    54571 82609.291 Have now loaded an ALMANAC
    54571 82609.291 state = ONCORE_RUN
    54571 82609.291 SSstate = ONCORE_SS_DONE
    54571 82610.401 ONCORE: Detected TRAIM, TRAIM = ON
    54571 82610.401 Input says TRAIM = -1
    54571 82610.401 Model # says TRAIM = 1
    54571 82610.401 Testing says TRAIM = 1
    54571 82610.401 Using TRAIM = 1
    54571 82610.421 PPS Offset is set to 0 ns
    54571 82610.431 Satellite mask angle is 0 degrees
  14. Enjoy and impress your friends with your timing receiver, just like I impressed you ; -)
April 18th, 2008

Remco meets Joe Walsh (The Eagles) …. again !

pa2dw-wb6acu-pg0a-klein.jpgAlso this year Joe Walsh invited me, and a few friends, as VIP to his concert of The Eagles. Last time we did not bring a present and we felt a bit guilty. So this time Dick arranged an old Philips tube for Joe and a tile ‘Delfts Blauw’ to hang up in Joe’s shack to remember us.

Back stage there was tasty food. We were facilitated by Smokey, Joe’s personal assistant, and we reckon Smokey will find a way to transport the tube into The States : -)

Fltr: Dick, PA2DW, Joe WB6ACU and Remco PG0A/PA3FYM.

Oh yes, I almost forgot. The concert was great, the sound sublime and good old times revived!

73, Joe & Smokey!