RCA Guideplus gold gemstar analog or digital
Most of the RCA GuidePlus Gold gemstar TVs worked with analog TV signals (NTSC) only. The Guide+ information was only broadcast in NTSC signals and is no longer being provided. If you can check the date of manufacture of the TV, you can use the size to check if it had an ATSC tuner added if it was made for the US market. 37"+ TVs had to have a digital tuner in second half of 2005. 25" TVs needed to have the ATSC tuner after March, 2006. The next year all TVs had to have a digital tuner.
I hope this helps. Please add a comment with the model number of the TV, if you would like me to confirm the tuner information on your set.
(The RCA F31317 TV with Guide+ was manufactured in 2000 and thus only has a NTSC tuner.)