# Transmitter HRS/PCM Explanation ??



## Madmarti (Mar 29, 2005)

What is the difference between HRS and PCM? I am looking to upgrade to either a KO EX-10 HElios or an M8 and I see these terms thrown around, but do not know what they mean. Is the M8 HRS? What does it mean and what should I look for in choosing a radio for Off-road racing. 
Thanks


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## Tres (May 10, 1999)

HRS (High Response Speed) 
In HRS mode, the transmitter sends out signals at twice the rate of typical FM systems


PCM (Pulse Code Modulation)


These are 2 seperate things....

Here's some good info on PCM:
http://www.futaba-rc.com/faq/faq-pcm1024.html


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## Madmarti (Mar 29, 2005)

*PCM / HRS which is better for RC off road.*

Ahh Which is better?


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## DynoMoHum (Sep 25, 2001)

I've never used a HRS radio... I have used a Futaba PCM system however.... and I've NEVER felt any need for more speed associated with my radio to car communications... So if HRS is just increased signaling speed... I'm not sure what if any bennift there would be to it...

Pulse Code Modulation... is basicly a digital signal/code that is transmited along with the typical radio data. The transmiter generates the code, the receiver verifys the code... if the code isn't right, the receiver ignores the signal, assuming it was invalid. This protects against noise and/or interfearance from non PCM radios... To my knowlege all Futaba PCM radios use the same 'code', so it will not protect from interfearance casued by another Futbaba PCM radio that is on the same frequency...

Basicly PCM is a realtively simple way to offer some digital protection for a radio signal. Think of it as error rejection...

What I don't know is why there aren't multiple 'codes' that are user selectable... If there were, it would be reasonable to protect to some extent even from other PCMradios on the same Frequency... but to my knowlege this kind of thing does not exsist in the PCM systems I know of.


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