CSM cyclock

[ChrisB]

Could be interesting, non-dx7 tx's don't hold the resolution during the full stick movement, I have no idea if the dx7 does or not...

Trev

I think the DX7 stuff caters for this,not 100% sure but if it does then maybe part of what the Cyclock offers is not needed when using Spektrum,i wonder if the module based systems are the same??

[trvo]

We'll see, I also like the fact that I can limit travel on the cyclock in a circular movement rather than the standard tx square shape, I currently have a cyclic disk in my tx but I may actually be able to take it out and shut Jim up about needing the full square area for planks...

Trev

[jimbob]

I don't remember speaking?

[trvo]

Different Jim

[Nutz]

I Tried to post this before the interrupted forum service.



That is a good question R50L, I was under the impression that the latency was introduced before the RF modulation and it was the way the signal was prepared to be broadcasted (i.e. processor)

I believe that the Spektrum modules will work from a PPM signal and convert it into 2.4GHz which would mean you would lose,

Model Match
Servo Sync
Reduced Latency

I have notice on the advertising bumph they do not mention the above issue which is why I am only presuming at this stage, I think will try and get clarification on this.

[Nutz]

I don't remember speaking?

Well we would have a hard time to shut you up

[Nutz]

Just found this on Spektrums site, it does not mention servo sync though it says it is feeding from the PPM stream so I would expect servo lag.

Will Model Match work with the Module System?


No. Model Match is a patented feature that prevents a model from being operated using the wrong model memory. Model Match can only be integrated into a dedicated Spektrum transmitter such as the Spektrum DX7. The programming necessary to make Model Match functional must be embedded into the transmitter´s programming.

Back to Top

I hear a lot about latency and response time. Supposedly the DX7 is faster than any 72MHz systems. Is the Module System as fast as the DX7?
The DX7 is a purpose-built 2.4GHz spread spectrum radio. With the DX7, the stick inputs are directly converted to digital code bypassing the PPM stream. This is the primary reason the DX7 is so fast and responsive. The module system needs to utilize the transmitter´s PPM stream and converts it to the appropriate digital code. Because of this extra processing step, the module system cannot be as fast as a dedicated system. It´s important to remember that the PPM stream is actually faster than PCM. In reality, the latency and response time of the Spektrum Module System is virtually identical to PCM systems.

[trvo]

Latency is produced before transmission, and the stick to xmission signal in the DX7 is slow, but the xmission from tx to rx is fast thus making it seem faster than normal.

In the 14mz it is the opposite, stick to xmission is fast, and as with all 35mhz systems, the tx to rx xmission is slow.

The new modules work in PPM mode as you suggest, but that means that the internals of the transmitter will be working at a very low resolution. I can see it being faster than normal 35mhz for transmission but you would loose out on the resolution, meaning accuracy problems.

Trev

[Nutz]

Anyone know what the resultion of the DX7 is compared to a 35Mhz FF9 on PPM or PCM?

[trvo]

I think that the DX7 would be faster since it is bypassing a lot of the slow internals that a normal ppm / pcm radio would use...but that's a guess...

I have a FF9 if anyone knows how to get this data from it? Very much doubt home equipment is up to the job...

Trev

[trvo]

http://www.rcheliaddict.co.uk/attach...2&d=1174658951

Here ya go...

Trev

[Nutz]

I have seen that chart, did you see the artical that moyesboy (sorry if I spelt the name wrong) posted regarding latency on PPM & PCM???

See if I can find it.


found it
http://graphics.tudelft.nl/~wouter/p.../pasman03i.pdf

[trvo]

Very interesting, will have to digest it fully when I have some time.

I'll just have to limit my investigations to 'how it feels' since I don't have that sort of equipment lying around at home

Trev

[Edders]

also rember that some of the latency you get is from the transmitter doing some maths before broadcasting the signal out and i cant rember the figures but the cyclock is quicker at the proccessing due to having two procceesors (or something like that)

also for resolution a standard jr box has say 300 points 100 each way for standard travel and 50 each way for ATV's so by having your travels set to 100 each way you are loosing 1/3 of the acuracy (i hope I got my maths right)

[Ashley Davis]

in PCM mode a JR 9X2 is only marginally slower than the DX7. To run the module it will be in PPM mode which is faster than PCM mode. Plus you have the faster transmission rate of 2.4 ghz.

I think the 9X2 module is worthwhile for these reasons, other tx I'm not so sure.