A while ago I had posted a way to send EbNaut directly from a u-blox GPS device without further hardware, using multiple concatenated batch scripts: 
https://klubnl.pl/rsgb_lf_group-archives/html/rsgb_lf_group/2019-02/msg00052.html
Now I have simplified the method a bit, so only a single short batch file (attached here as txt) is needed.

Download setubx2.exe software from the specified URL, and generate your desired sequence using Paul Nicholsons ebnaut-tx and "Save Rows" (i.e with one symbol per line) as "pskln.txt". You can configure transmit parameters by editing the first lines in the script:
 startminutes=30: start time on multiple of number minutes (e.g on the next half hour),
 sym=3 symbol duration in seconds (integer, 1 to 60),
 freq=137536 frequency (any integer Hz). Note that 137536 Hz happens to be a sweet spot in terms of low spurious sidebands for the LEA-6T,
 frac=.000 a possible fractional-Hz part of the frequency. This will be approximated by phase steps so should not be large,
 comport=com5 the virtual serial port where the u-blox device is connected.

The "setubx2 0" line can disable the output after the sequence has been completed. For a repeating beacon (e.g. every half hour), you can enable the "@goto loop" line by removing double colons. Finally save the script as a .bat and start it by double-clicking or from a console. 

Note that  while the script is running you should avoid mouse clicks or key entries into the console window, as these would destroy timing by inhibiting or prematurely aborting the timeout commands.

73, Markus