This kit has been retired, and replaced by the SKM52 GPS module kit.
This is a GPS module kit suitable for the Ultimate1, Ultimate2 and Ultimate3 QRSS/WSPR kits. It is plug-and-play compatible with the Ultimate QRSS/WSPR kits, connecting directly with no voltage regulators, pull-up/down resistors etc., and uses the default baud rate settings of the Ultimate kits. When used with the Ultimate QRSS/WSPR kits, the GPS module will provide accurate time-keeping, frequency calibration, and location information (for encoding the Maidenhead locator automatically into WSPR messages).
The kit contains the following:
- GPS Module, size 28 x 28mm with integral 25 x 25mm patch antenna. Includes voltage regulator and Green 1pps LED.
- Matching 6-way cable, 15cm length with connector
- Plastic case, includes two plastic parts, rubber grommet, and 4 screws to close the case.
This module uses a SiRF III chipset. The module size is 28 x 28mm and it includes a patch antenna sized 25 x 25mm. Click here to view the module datasheet.
From top to bottom in the photos below, the connections are: Boot (leave floating), Gnd, RxD (leave floating), TxD serial data output, Vcc, 1pps output.
The kit can be supplied with two different kinds of cable. The difference is the colouring of the wires.
Cable style 1 has a white wire on one side and a yellow wire on the other side. This is the most common type of cable. In this case to use the module just connect:
BLACK wire to Ultimate board Gnd connection
RED wire to Ultimate board 5V connection
BLUE wire to Ultimate board RxD connection
WHITE wire to Ultimate board PPS connection
Cable style 2 has a red wire on one side and a white wire on the other side. In this case to use the module just connect:
BLUE wire to Ultimate board Gnd connection
BLACK wire to Ultimate board 5V connection
YELLOW wire to Ultimate board RxD connection
RED wire to Ultimate board PPS connection
1) I recommend the use of the Ultimate2 firmware version v2.04, with the "GPS Mode" parameter set to "2". The kit should work with lower firmware versions too, but v2.04 has built-in tolerance of signal dropouts so the performance is better. If using the Ultimate 1 kit, use firmware version v1.08 or above.
2) Inexpensive GPS modules such as the VK16E do not have very accurate 1pps signals. A "Huff Puff" method calibration mechanism was introduced into v2.07 and v3.01 (for Ultimate2 and Ultimate3 kits respectively). Using this it is possible to get very accurate frequency calibration using this GPS module. These versions or above are therefore recommended with the GPS module for use with the U2 and U3 kits. The Ultimate1 kit anyway uses a Huff Puff-like method for frequency lock, so any v1.xx version is fine.
3) You will probably find that like many GPS modules that use a patch antenna, the GPS module may need to be by a window or outside. GPS signals seem to vary substantially in strength depending on location and surrounding buildings etc. The GPS module may also benefit from being further away from the Ultimate kit, depending on your shack layout and grounding. For this reason you may want to connect the GPS module to the kit using several metres of wire. I recommend the use of a screened cable with the screen connected to Gnd.
4) The Module has a Green LED as shown in the pictures above, which is continuously ON while the GPS module is searching for satellite lock, and flashes at 1 pulse per second when locked.
Modification by Antonio EA1CDV
Antonio notes that the 1pps LED is very useful for knowing when the GPS has achieved satellite lock status, however it is not visible when the GPS board is put in its plastic case! His solution is to use a fibre-optic light guide to route some light to a hole in the case. Please see his blog entry here, for more details.