GPS Data Interconnect

Select Other Pages Here a) GPS antenns and receivers a2) GPS antenna information 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

This is the part of the wiring standard that connects the GPS data output to the Data Input of the TNC.

In 1996, the plan was to have a single GPS interconnect, capable of supplying +12 volts DC power to the GPS units, while also allowing the GPS unit to pass data to the TNC through the same connector. Unfortunately, we found that the female stereo plugs come with varying amounts of reliability, but that you can't always predict how much. (We would have intermittent power and data in some cases, do to vibration, and flexing of the data cables.)

As a result, in 1997, we reverted back to the connector recommended by Bob Bruninga, WB6APR. This uses a mono jack, instead of stereo, which generally seems to have a higher reliability for the data, but requires a separate cable to provide power to the GPS receiver.

NOTE: Since the 1996 scheme deviates from the connector recommended by Bob Bruninga, you must beware of using a mono-jack-GPS unit with the power-injecting data interconnects. If you insert a male mono connector into a power-supplying female, you will probably short the power supply, possibly damaging cables, adapters, and possibly equipment!

Garmin units

For the Garmin 45, GPS II, and some other Garmin units, there is a set of power & data connector/harnesses available. (Ham Radio Outlet and West Marine sell one cable only for $40, or the cable & cradle for $65, approximately.) However, the leads are long. Rather than cutting them down for our use, we recommend preparing the end according to the specification shown below, and then coiling the excess cable.

Bob Bruninga's Standard

As stated above, the intention was to provide a standard interconnect between TNC and GPS serial ports. The shield of the 1/8" mini-plug/jack is the signal ground, and the tip is the data from the GPS receiver to the TNC serial input. Power to the TNC was handled separately.

We adopted this standard for the 1995 B2V Relay. This was the connection between the Trimble SVEE-6 receiver (DB-9 jack) and the AEA PK-12 TNC (DB-25 jack). The colors were chosen to identify and differentiate the wires in the harness within the 1995 packages.

This is a proposed schematic which allows the GPS power to be coupled between the power source, and an existing radio. (A similar power tapping scheme could be used to provide power for a TNC.) The data output from the GPS receiver is sent to the TNC via separate wires, to a mono-1/8" mini-phone plug. This would plug into an adapter connected to the TNC.

Select Other Pages Here a) GPS antenns and receivers a2) GPS antenna information 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

Copyright 1996-2002, David K. Z. Harris, N6UOW
Questions? Comments? Additions? Email b2v at baker2vegas.org

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