How can I configure UNO to read TTL data (5V High/Low) off a Radar Gun?

I have a radar gun which has three connective prongs (normally a corded handle slides there). The following is a picture of the gun and the bottom where the prongs are. From testing and from the manual, I know that the first two prongs are 7.5 VDC and Ground, while the third prong is used for data transmission. The following third image are the given specs for the data prong.

I would like to directly access the third prong, but am unsure how to do it. I am thinking that I could set my UNO serial monitor for 1200 Baud with CRs, but do not know how the +5V High/Low specification would be met. It seems I would need at least three wires, but there is only one prong. Any ideas would be greatly appreciated. Thanks.

A TTL/USB converter?

I use one to communicate b/w a PC and GPS module or a Bluetooth module.

You would have to be sure of voltages.

If you are only receiving data from the unit then you would connect the prong to the converter's RX pin. The converter's TX pin wouldn't connect to anything.

I would expect they need a common ground.

1200 bits per second?
Hook it to an I/O pin and bit-bang / soft serial it.
Or use a spare serial port on a Mega.

(Thinks: do the UART clocks go that slow?)

I am struggling to understand what you don't understand. The data TX from the gun is 5V, the same as for any 5V Arduino. Connect the TX on the gun to Rx on your Arduino, preferably one with a spare serial port such as a Mega or a Nano Every. Don't forget the ground. The specification says 12V for the power, not sure where you got 7V5 from.

As AWOL said though, you might have a problem with 1200 bps, very slow that.

Also, your description of which prong does what doesn't match the data sheet.

Thank you for your replies. I am a bit confused where the ground wire from the Arduino might go. Would it connect to the ground prong on the radar gun itself? Normally for TTL devices, there is a place where I could connect the wires coming out of the arduino (from 5V, ground, and RX). But here, it seems all I have is a single prong for TTL, would I be connecting all three wires out of the arduino and clipping it onto the single prong? thank you

GND to GND, DATA to Arduino I/O pin.
Two wires.

Thank you all for your help, especially regarding the wiring configuration. It worked and it looks like its able to read the TTL, thank you!!