53421
The " front porch " is a brief ( about 1.5 microsecond ) period inserted between the end of each transmitted line of picture and the leading edge of the next line sync pulse .
 microsecond
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 microsecond