Select Other Pages Here a2) GPS antenna information b) GPS to TNC data cables c) TNC GPS Data interconnect d) TNC-interconnect cables d+e) TNC-Radio interconnect e) Radio-interconnect cables h) Power Splitter Harness i) Mag-mount antennas o) Cable and Wiring Overview -) Baker-to-Vegas HQ Page
Please look over the whole page, because we have new info below!
Every vehicle that we will be tracking will have a GPS receiver, bundled with the TNC and radio, in a single, integrated APRS Tracker Package. (This may be a TAPR Mic-E and a radio.) Each vehicle should also have an externally-mounted GPS antenna, with adequate low-loss feedline. This will allow us keep the receiver inside the vehicle, inside a package with the radio and TNC, while allowing the antenna the best view of the available satellites.
GPS Units
Make & Model
display
antenna input
serial output
Notes
Trimble SVEE-6
none
female SMA
DB-9 female, RS-232
1
Garmin GPS-45
backlit LCD
female BNC
Garmin 4-pin, RS-232
2
Garmin GPS II, II+
backlit LCD, can rotate 90 deg.
2, 3
Garmin 12-XL
LCD
female MCX
TAPR Mic-E
female BNC*
4
GPS Antennas
Maker & Model
coax info
passive?
magnetic?
Blackjack (LRF patch)
3' RG-58 male BNC
passive
no
Lowe
10' mini-coax male BNC
active, +25dB
yes
2, 3,4
Jano Metals SM-65
5 meters (15') BNC/SMA/MCX (you choose)
Jano Metals
active, +30dB
2, 3, 4
If you are interested in seeing the pictures of some of these antennas discussed here, you can click on the model numbers in the table, or check the GPS Antennas page. This page has cost information, and vendor contact information for the Blackjack, Jano, and Lowe units, as well as notes about others. This page will auto-load a pair of pictures that are 160 KB combined. If you are on a slow modem, this may take a little while, but I think it will be worth your wait.
Since most of the GPS receivers we will be using will be loaned by local hams, and many do not have external antennas to send along, we will need to consider building or buying antennas for these loaner units. We would appreciate hearing from folks that have tried various external antennas (active or not) and let us know what you thought of them. If you liked the antenna(s) you tried, please include contact information for the vendor(s). You can send me email, or send me a message on packet to N6UOW@N6QMY.
I have three of the normal Blackjacks for testing. We've found that they perform at least as well as the standard Garmin antenna, but these are equipped with only 1 meter of RG-58 to extend it away from the receiver. It seems to have slightly better performance for satellites that are lower on the horizon. Our tests are subjective, based mainly on the signal strength indication on the Garmin unit LCD display. We will be testing one of these antennas with the optional 10' coax attached, and compare the performance.
Pac Comm is reselling a Trimble antenna for ~$50.00, plus shipping. The antenna is Trimble part number 28367-00. Pac Comm can be reached by phone at 800.486.7388.
Jano Metal Products, in Nepean, Ontario, Canada (K2J 3Y4). They are preparing to market a model in the US, that has been selling in Europe. The price for the passive antenna (SM-65) is $32 (US dollars), and will come with a 3 meter (~10 foot) coax cable, with an SMA Male connector. Jano also has an active antenna, boasting a 30 dB gain figure, and is a magnetic mount. This comes with a 10 meter lead, terminated with a male micro-connector that connects to the female MCX connector. The price on these is $48 (US). Shipping is from Ontario, Canada.
I've tested both the passive and active antennas from Jano, and found them both to be very good performers, especially with satellites that are closer to the horizon. The power draw on the active unit is slightly more than the Lowe antenna, but the gain seems to be better as well. (My testing was primarily done with two Garmin GPS units, and tests were made at the same time, in the clear.) More information and pictures are available on the antennas page.
Lowe Electronics markets an Active (amplified) GPS antenna, sold in the United Kingdom, and costs $65 to ship by airmail to the U.S. It includes a long coax lead, and a magnetic base! You can find info and order it by checking their web page at www.lowe.co.uk/gpsant.html, but be forewarned that they have a picture on the page that is 185 KB, and it takes a bit of time if you're using a modem to browse. It's a nice picture of the antenna, but the picture file is BIG. (Rumor has it that this antenna may be available from a firm in the U.S. for slightly less, but I cannot track down vendor information yet. If you can give me a clue please send me email.)
Ham Radio Outlet is carrying the Garmin 35, which is basically the same as a Garmin 45, but with a built-in antenna, rather than the removable antenna on the 45. The 35 does have a serial port built in, so it can be used for APRS, but you lose the ability to connect to an external antenna. The trade-off is that the cost is under $200. The Garmin 45 seems to have been replaced by the newer Garmin 45XL, which looks the same, but appears to be a nitrogen-filled unit, and sells for less than $300. There is also a newer Garmin GPS II, which has a serial output (good for APRS), and can connect to an external antenna. However, the unit seems to be not designed as a hand-held unit, but appears meant for mobile mounting. This also costs less than $200. Cable harnesses for the Garmin line to external power and computers/TNCs are available from between $30-65.00.
You can also use the DeLorme TravelMate GPS receiver for APRS as well! If you tie the transmit data to the receive data lines, the unit will start itself, and send posit strings useful for APRS trackers.
West Marine, in Palo Alto is also a good source for GPS receivers and some wiring harnesses. Their pricing is reasonable, and they will meet the advertised prices for other vendors. Garmin also offers an optional 'Active Antenna', a small antenna with a built-in amplifier, for approximately $140.00, which we bought at West Marine, and which has performed very well. West Marine also sells the Garmin GA-28 Active Antenna for $130.00. This comes with 12' of coax, and can be threaded onto a pipe fitting for mounting. There are also a few assorted mounting adapters available for this antenna at West Marine.
REI, purveyor of sturdy outdoor gear and equipment, is also selling GPS units alongside backpacks, and sunscreen! The next time you are looking for goodies for your grab-and-go bag, check the selection and pricing on the GPS units as well. (I was excited to hear that REI now carries GPS units, since they are my favorite place to shop for bags, packs, and other supplies we use for our Baker-to-Vegas efforts.)
TAPR (Tucson Amateur Packet Radio) are offering a GPS core. The unit is the Garmin GPS30, for $99.95 (includes shipping), only during the month of August (1997). The unit uses the Garmin 20 receiver core inside. More info is available at the TAPR web site (www.tapr.org).The TAPR GPS Index has a bunch of deals for GPS core receivers, as well as antennas.