The ID-31 and ID-51 series transceivers, with some limitations, are able to output GPS data to other radios DATA terminals. By making good use of this, I found out a method of using them as an external GPS data source for some other Icom radios.

Using an ID-31 or ID-51 as a GPS data source

The Icom ID-31 or ID-51 series radios with built-in GPS receivers have a function that enables an output of GPS data to your PC when using a data cable. However, while no D-STAR signal is received, GPS data is not output. This is because of the RS-232C to USB Converter IC specifications. It is same when connecting them to the IC-9700, IC-9100 and IC-7100, so we have no choice but to use a GARMIN GPS receiver (in the case of Japan).

Left: ID-800 (Discontinued model, no buit-in GPS receiver) connected to an external GPS receiver
Right: Garmin 18 x PC Receiver

GPS data output examples. The IC-7100 can receive GPS data only from the ID-31PLUS, while the IC-9700 can receive data from the ID-51PLUS2 too.

Upper left: From the ID-31PLUS to the IC-7100
Upper right: From the ID-51PLUS2 to the IC-7100
Lower left: From the ID-31PLUS to the IC-9700
Lower right: From the ID-51PLUS2 to the IC-9700

Here are some benefits of an external GPS receiver:
- Automatic time correction
- Searching Nearest Repeater
- Measuring Distance to other stations
- Transmitting MY station GPS data
It is not that difficult to connect the Icom transceivers together, just a little soldering work to make a cable. I hope that you try this!

A combination of receiving and ouputting GPS data

Building the connecting cable

Let’s build a connecting cable with 2.5 mm stereo plugs and stereo cable (2-conductor and sheild wires). This type of cable is not usually sold so it has to be a handmade.

Wiring diagram of the cross cable

<Materials>
- A desired length of stereo cable
- Two 2.5 mm stereo plugs (the plug base diameter should be less than 6.0 mm)

As shown in the wiring diagram above, solder TxD (1) of the source radio plug to RxD (1) of the target radio plug, and then solder RxD (2) to TxD (2).

Upper: Example of a cable with a 2.5 mm stereo plug already installed.
Lower: The cross stereo cable after soldering on another 2.5 mm plug

Settings of the external GPS source radio (Example: ID-31PLUS)

Push [MENU] of the radio, and then set the items listed below. - Set GPS Select to “Internal GPS.” (MENU > GPS > GPS Set > GPS Select)
- Set GPS Out (To DATA jack) to “ON.” (MENU > GPS > GPS Set > GPS Out (To DATA Jack))
- Set GPS Auto TX to “OFF.” (MENU > GPS > GPS Auto TX)
- Set Data Speed to “9600 bps.” (MENU > Function > Data Speed) ^*1
- Set CI-V (DATA Jack) to “OFF” (MENU > Function > CI-V > CI-V (DATA Jack)) ^*2

*1 The data speed value applies to both DV data and GPS communication.
*2 Data terminal does not output GPS data if the terminal is set to output other signal such as CI-V. After you make an image(picture) transmission, set the [CI-V (DATA terminal)] to the initial value OFF.

Settings of the GPS data target radio

When using the IC-9700, IC-9100 or the IC-7100, set the items listed below.

■When using the IC-9700
1. Touch [SET] in the MENU screen.
2. Set DATA Function to “GPS/Weather.” (Connectors > USB (B)/DATA Function > DATA Function)
3. Touch [GPS] in the MENU screen.
4. Set GPS Select to “External GPS.” (GPS Set > GPS Select)
5. Set GPS Receiver Baud Rate to “9600.” (GPS Set > GPS Receiver Baud Rate)

■When using the IC-9100
1. Hold down [CALL・GPS] for 1 second to display the GPS screen.
2. Push [SET] (F-5) to enter the GPS Set mode.
3. Set GPS Receiver Baud to “9600.”

■When using the IC-7100
1. Push [SET] to enter the Set mode.
2. Set GPS Select to “External GPS.” (GPS > GPS Set > GPS Select)
3. Set GPS Receiver Baud rate to “9600.” (GPS > GPS Set > GPS Receiver Baud rate)
4. Set DATA1 Function to “GPS.” (Connectors > USB2/DATA1 Function > DATA1 Function)

ID-31PLUS as an external GPS, connected to an IC-7100

At Tokyo Ham Fair 2019, a demonstration of receiving GPS data on an IC-7100 from an ID-31PLUS, used as an external GPS source, was given at the Icom exibition booth. I wrote this article to let people know that you can easily use your current handy radio as an external GPS source! I hope this article can help you.

Demonstration at Tokyo Ham Fair 2019 (1)

Demonstration at Tokyo Ham Fair 2019 (2)