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-   -   3PK - Spektrum System (https://www.rctech.net/forum/radio-electronics/67107-3pk-spektrum-system.html)

nimble 04-01-2005 09:47 AM


The Spektrum is the fastest response system available. Something like 5.8ms, I can get the exact number but Futaba's HRS is around 8ms......and the resolution is just short of 4 times that of a 1024 PCM system.
In fact, the Spektrum module ADDS an ADDITIONAL MINIMUM latency of 5.6ms. If HRS is 8ms, Spektrum will be 13.6ms...

It is not easy to see that difference unless the car goes very fast and has fast servos.

JLock 04-01-2005 10:02 AM

Got my Spektrum for my 3pk on Tuesday and through it in my car (MTX-3) immediately. Static test: it works fine but will be testing it at the track this weekend.

The instruction do tell you if you have it in PCM or are using the HRS mode, you have to change it over to PPM. I read the instructions before installing.:nod: I am curious about the fail-safe feature since I had a fail-safe (from Dynamite) on my car which worked flawlessly.

The Spektrum for the 3pk works on the 3pjs as well as the Hitec CRX and SRX. So, for the guy that has the 3pjs, it should work with your system.

If the system works like advertised, all of my r/c cars that I run will be converted.

In my local area, Mike's Hobby Shop in Carrollton, TX has them in stock (as well as for the JR R-1) for $139.99. You can contact him through his website, www.mikeshobbyshop.com. He does ship worldwide so contact him through his site and tell him I sent you.;)

rskiba 04-01-2005 11:57 AM


Originally posted by nimble
In fact, the Spektrum module ADDS an ADDITIONAL MINIMUM latency of 5.6ms. If HRS is 8ms, Spektrum will be 13.6ms...

It is not easy to see that difference unless the car goes very fast and has fast servos.

Nimble, why do you say that it ADDS latency? I am not sure I understand?

nimble 04-01-2005 12:25 PM

A digital module must FIRST decode the analog signal that is sent to the module before it can transmit it digitally. This requires approximately 6ms. The existing analog modules transmit the analog data immediately.

cvt01 04-01-2005 01:07 PM

"A digital module must FIRST decode the analog signal that is sent to the module before it can transmit it digitally. This requires approximately 6ms. The existing analog modules transmit the analog data immediately."


Sounds logical to me...

You should tell this to the guys at RCDriver (or RccarAction - I don't remember :confused: ) since they stated that this is the fastest system on the RC market and they compared the HRS system to the Spektrum.

JLock 04-01-2005 01:36 PM

Who cares if it is not a fraction of a second faster or slower than the HRS, PCM, OPP, PDQ, or whatever other system is available. Most average racers don't really notice response time changes to the Nth degree anyway. Lets hope that it works for all the systems it is available for and eliminate the need to use crystals!!! I just get tired of waiting for frequency hogs to give up the clip from the board so I can get some practice in at big races and tired of getting bogged down with useless splitting hairs on technical dribble that most of us could care less about.

Brandon Melton 04-01-2005 05:33 PM

deleted. found my answer on spektrum's website.

Galifrey 04-02-2005 05:35 AM


Originally posted by nimble
A digital module must FIRST decode the analog signal that is sent to the module before it can transmit it digitally. This requires approximately 6ms. The existing analog modules transmit the analog data immediately.

Thats not strictly true as the Module still has to convert the analog signal into a an RF wave...

That is not done instantaneously as you suggest and the speed at which this is done is included in the futaba HRS 8ms quoted speed...

The 5.6ms is the equivalent it is not in addition too...

This sytem was designed by Paul Beard of Modelavionics for helicopters and the rights sold to horizon/spektrum... I am luckily a field rep for Modelavionics and have discussed this issue at length prior to the sell out...

:nod:


SPEKTRUM Q&A

IS THE RESPONSE TIME FAST ENOUGH?
Latency (response time) is a measure of how long it takes from the time you move the steering wheel or throttle to the time the servos or the speed control react in the car. Even in sport radios, it's often so fast that the delays are undetectable, but for the people who race their radio stats, the Spektrum has the fastest response time ever—5.6 milliseconds.
:ha:

JayBee 04-02-2005 08:21 AM


Originally posted by Galifrey
Thats not strictly true as the Module still has to convert the analog signal into a an RF wave...

That is not done instantaneously as you suggest and the speed at which this is done is included in the futaba HRS 8ms quoted speed...

The 5.6ms is the equivalent it is not in addition too...

This sytem was designed by Paul Beard of Modelavionics for helicopters and the rights sold to horizon/spektrum... I am luckily a field rep for Modelavionics and have discussed this issue at length prior to the sell out...

:nod:



:ha:

Finally, someone who knows how this works ;) - JB

John Fontaine 04-02-2005 10:12 AM

I should have my system on tuesday....how long till I can get additional receivers?!?

nimble 04-02-2005 10:37 AM


Who cares if it is not a fraction of a second faster or slower than the HRS, PCM, OPP, PDQ, or whatever other system is available.
JLock, clearly, A LOT OF PEOPLE CARE, particularly those that invest hundreds of hours and thousands of dollars to make it faster.

Gailifrey, clearly you are not an engineer, and don't understand how analog signals become RF. Please ask Paul Beard to come on this forum and explain how his module can transmit FASTER than the rate in which his module gets the data to transmit.

Galifrey 04-02-2005 02:36 PM


Originally posted by nimble
JLock, clearly, A LOT OF PEOPLE CARE, particularly those that invest hundreds of hours and thousands of dollars to make it faster.

Gailifrey, clearly you are not an engineer, and don't understand how analog signals become RF. Please ask Paul Beard to come on this forum and explain how his module can transmit FASTER than the rate in which his module gets the data to transmit.

It doesnt, 8ms is the speed the futaba servo reacts to movement under HRS...

Thats including the module overhead....

I guess what you are saying is spektrumrc are lying about the quoted speed, as I clearly posted their definition and their response time... measured not assumed...

I am not going to bring another to this argument as Paul designed the system for the 9ZHP and things have been tweaked a bit since then...

BTW the latency I have for the 3PK is 3ms to the rx module and the module takes another 5ms on average to get the signal to the rx and out again due to the lower frequency and the fact it modulates in FM not microwave digital... Kinda LP vs CD... LP ultimate resolution CD ultimate clarity and lack of distortion... except in this case spektrum have given us 4x the reolution as well... who would have thought.. ;)

It takes 1.5ms for the neutral pulse on a radio, therefore the latency is always a minimum of 1.5ms using a PWM/PAM/PPM signal does a digital signal take 1.5ms to register the change... No... theres the start of our reduction in latency at the RX already...

;)

RcMonk 04-02-2005 03:57 PM

Cool John. I got mine today (KO system) and have been playing around with it today.


Originally posted by John Fontaine
I should have my system on tuesday....how long till I can get additional receivers?!?

JJ187RC 04-02-2005 04:40 PM

I installed mine over the last couple of days, just a little at a time. I had no problems getting it setup and it binded right off. I will be racing with it tomorrow and that will be the true test.

TCR 04-02-2005 04:47 PM

fact is its fast as hell if your is lagging send it in, have it updated if your unsatisfied


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