Identifying the Required Pins on the Radio Service Connector

For the Control Radio and RoIP Gateway to work together in ANALOG mode, the devices must be connected using 4 or 5 conductors that carry audio and control signals between them. What you need to identify, locate, and verify on the Control Radio: the service connector pins with the control signals "ExtPTT" and "CSQ Detect", and the service connector pins or dedicated jacks for the microphone input and the line-level output of received audio.

Consult the documentation for your radio model. In the description of its service connector, look for the terms mentioned above or similar ones, and mark them as candidates for further connectivity testing. On some radio models, the required signal inputs and/or outputs "ExtPTT" and "CSQ Detect" may not be present on the service connector. Their functions may be assigned to general-purpose programmable input/output pins (GPIO).

To configure general-purpose programmable input/output pins, try the following steps:

Once all required pins and connectors have been successfully identified, proceed to the direct testing stage.

Checking the Common Ground Wire for Device Interconnection

With the Control Radio turned off and completely disconnected from its power supply, use the multimeter in resistance measurement mode to check for the presence of ground at the service connector pin assigned as "GND". The multimeter should show zero or near-zero resistance between the "GND" pin and the metal chassis elements of the radio, as well as the negative conductor of the radio power input on its 12V connector.

Checking the Radio Input for Transmit Mode Activation

This test is performed on the Control Radio connected to its power supply and turned on in working condition. Before testing, verify in the radio documentation which control signal is required to activate the radio's transmit mode. Typically, "GND" is used: i.e., the "ExtPTT" pin is shorted to the radio chassis/ground. If this is specified as such, use a conductor connected to "GND" or to "chassis/power supply negative" to apply the control signal to the "ExtPTT" input. The radio should switch to transmit mode. If the Control Radio switches to transmit mode when the control signal is applied, note the verified pin number on the radio service connector and its designation. Write the pin number to the table at the bottom of the article in position 1.

Checking the Radio Call Detection Output

If the documentation for your radio includes a "CSQ Detect, PL/DPL Detect, Group Detect, Channel activity" control signal output, use this signal after verifying its operability on the radio.

This test is performed on the Control Radio connected to its power supply and turned on in working condition.

Connect the multimeter in voltage measurement mode between the "CSQ Detect" output (multimeter +) and the radio chassis/power supply negative (multimeter -).

Measure the voltage in standby mode and during call reception. To put the Control Radio into call reception mode, use the paired User Radio by pressing and holding its PTT.

If the voltage at the "CSQ Detect" output does not change between standby and call reception modes and remains near 0 V, this pin may require an external pull-up.

To check this configuration, connect the multimeter in voltage measurement mode between the radio's positive power supply (multimeter +) and the "CSQ Detect" output (multimeter -).

If the voltage measured at the "CSQ Detect" pin on the Control Radio changes within the ranges described above when switching between reception and standby modes, note the verified pin number on the radio service connector and its designation. Write the pin number to the table at the bottom of the article in position 2.

Preparing for Audio Input and Output Testing

After verifying that the speaker system and AUX cable are working, prepare the AUX cable for further use in the tests. To do this, cut the cable in half, strip its conductors, and prepare them for connection to the radio connectors.

Checking the Radio Microphone Input

Connect the radio's microphone input "ExtMic", as specified in the documentation, to the sound source using the half of the AUX cable with the Male 3.5 mm connector. Start audio playback on the sound source and then, using the conductors prepared earlier, apply the control signal to the "ExtPTT" input. The Control Radio should switch to transmit mode and transmit the audio signal to the paired User Radio. The audio should be clearly audible on the User Radio, free of noise, distortion, and/or interference. If you heard clear audio transmitted by the Control Radio on the paired User Radio, Note the verified pin number on the radio service connector and its designation. Write the pin number to the table at the bottom of the article in position 3.

Checking the Radio Audio Output

Connect the radio's audio output "RX audio", as specified in the documentation, to the speaker system using the half of the AUX cable with the Female 3.5 mm connector. Using the paired User Radio, press its PTT and speak a few phrases into its microphone. The audio signal received by the Control Radio should be clearly audible on the connected speaker system, free of noise, distortion, and/or interference.

If you heard clear audio received by the Control Radio on the connected speaker system, note the verified pin number on the radio service connector and its designation. Write the pin number to the table at the bottom of the article in position 4.

PIN table and closing remarks

Pins with * are mandatory for the RoIP Gateway connection. The "CSQ Detect" control output is not mandatory but provides better incoming call detection.