Junior Member
Could you please let me know what are the differences between FM and PCM radios. Which one is better and why. Aslo, can the PCM radio be used with FM receivers and visa versa. I am totallty ignorant about PCM and would appreciate a detailed response from you before I purchase my next Futaba Radio. I already own two.
Rani
Rani
Senior Member
Hi, Rani!
I'll try to give you some brief basics, and then send you to some other resources to assist you.
first, MOST radios which do PCM also have a modulation setting to do PPM (which is the proper term for what most modelers call FM). The reason "FM" isn't the proper term is that both PPM and PCM both transmit on an FM wave.
OK, so lets back up a second. think of AM and FM like old telephones that were dial or the newer phones that are touchtone. The 2 phones care only about one thing -- can the phone company equipment understand it...it doesn't care what language the caller speaks (PPM or PCM) and it doesn't care what # the person is dialling (what channel the system is on), it cares only if the system understands pulse (AM) or touchtone (FM).
PCM is a digital, encoded signal. So it is digital like your digital cell phones. And it is encoded, so it is in a foreign language when compared to most FM radio signals.
the encoded is helpful because the receiver looks at everything it hears and checks the language that is coming at it. Think of it like a person who speaks only German in the US. The first thing that person does is listen for someone who is actually speaking something he understands -- GERMAN -- before he tries to communicate at all. This is roughly what PCM does -- checks the language first. if the data isn't in PCM language, then it chooses not to listen to that command because it wont be able to make any sense of it anyway.
OK, so that's my "what is FM or PCM" speach. :-) please don't feel foolish for asking -- this is the #1 "speech" i'm asked to give at work to various departments every day.
for more info on PPM vs PCM please go to www.futabarc.com, and go to the FAQ area.
I'll try to give you some brief basics, and then send you to some other resources to assist you.
first, MOST radios which do PCM also have a modulation setting to do PPM (which is the proper term for what most modelers call FM). The reason "FM" isn't the proper term is that both PPM and PCM both transmit on an FM wave.
OK, so lets back up a second. think of AM and FM like old telephones that were dial or the newer phones that are touchtone. The 2 phones care only about one thing -- can the phone company equipment understand it...it doesn't care what language the caller speaks (PPM or PCM) and it doesn't care what # the person is dialling (what channel the system is on), it cares only if the system understands pulse (AM) or touchtone (FM).
PCM is a digital, encoded signal. So it is digital like your digital cell phones. And it is encoded, so it is in a foreign language when compared to most FM radio signals.
the encoded is helpful because the receiver looks at everything it hears and checks the language that is coming at it. Think of it like a person who speaks only German in the US. The first thing that person does is listen for someone who is actually speaking something he understands -- GERMAN -- before he tries to communicate at all. This is roughly what PCM does -- checks the language first. if the data isn't in PCM language, then it chooses not to listen to that command because it wont be able to make any sense of it anyway.
OK, so that's my "what is FM or PCM" speach. :-) please don't feel foolish for asking -- this is the #1 "speech" i'm asked to give at work to various departments every day.
for more info on PPM vs PCM please go to www.futabarc.com, and go to the FAQ area.
