How can I transmit a TTL signal to a computer?
Your question is lacking specifics about the pulse's properties&mdash;e.g., pulse width (min,max); time interval between pulses (min,max), etc.

However, since you specifically mentioned National Instruments (NI) 'LabVIEW' software, NI and other companies sell data acquisition (DAQ) devices that are specifically designed for use with LabVIEW. Some of these DAQ devices are lower-cost, USB-based devices that you plug in to an available USB port on a computer that is running LabVIEW. You simply connect your TTL signal to one of the DAQ device's digital input pins, and then write a LabVIEW program (a.k.a., a "virtual instrument" or simply "VI") that monitors that digital input pin on the DAQ device. In other words, there's no need to create your own DAQ device when you can purchase a DAQ device that is specifically designed for use with LabVIEW. (n.b. This is not intended as a recommendation for, or endorsement of National Instruments or its products. In the interest of full disclosure, I sometimes use NI's LabVIEW software and DAQ devices.)

Additionally, there are free software libraries you can download that enable communication between LabVIEW and embedded computer boards like Arduino, Raspberry Pi, BeagleBone Black, etc. With these libraries you can, for example, create a basic data acquisition system around an Arduino board, and use a LabVIEW program to communicate with and control that Arduino board via a USB cable&mdash;e.g., to trigger data capture on the Arduino; to offload captured data from the Arduino to the LabVIEW program, etc. Two examples of these free software libraries for LabVIEW are:


National Instruments' LabVIEW Interface for Arduino Toolkit
MakerHub LINX for LabVIEW