Originally Posted by ilovetoflyfpv

Hi kha

Thanks for getting back to me. I'm interested in how FrSky compares with Orange Open LRS running Open LRSng in terms of resolution. According to Hi Model the FrSky V8FR-II RX for example is 3072 (how they arrived at that figure I'm not entirely sure). Orange Open LRS running Open LRSng in contrast is 1024 (10-bit). Would I be correct in thinking that there is only 1/3 the resolution? Is this significant enough to notice a difference when flying?

Cheers

Jase

The 10bit resolution is more than enough you wont notice the difference. What you may notice is the lower update rate on lower datarates which results in a bit jerky servo movement especially if telemetry is enabled.

Originally Posted by ilovetoflyfpv

Hi kha

Thanks for getting back to me. I'm interested in how FrSky compares with Orange Open LRS running Open LRSng in terms of resolution. According to Hi Model the FrSky V8FR-II RX for example is 3072 (how they arrived at that figure I'm not entirely sure). Orange Open LRS running Open LRSng in contrast is 1024 (10-bit). Would I be correct in thinking that there is only 1/3 the resolution? Is this significant enough to notice a difference when flying?

Cheers

Jase

Well, the 9X takes input at 10 bit (2^10 or 1024) or 11 bit (2048) depending on which algorithm you use, though the ADCs are actually 10 bit (or less due to electrical noise). If FrSky states a resolution of 3072 positions that leads me to believe they're using a 3MHz input timer to measure 1/3uS, and since servo pulses go from 1000-2000uS that would give around 3000 positions. This is probably upconverted to 12 bit or downconverted to 11 bit, however I think both are really too precise due to jitter, noise, and analogue servo resolution.

I remember someone actually measured the real resolution of servos. Very good servos had a precision of 2 µs, and normal servos about 4 µs.

4 µs is equivalent to (2ms - 1ms)/250 steps, or 8 bits.(256 steps)
2 µs is equivalent to (2ms - 1ms)/500 steps, or 9 bits.(512 steps)
1 µs is equivalent to (2ms - 1ms)/1000 steps, or 10 bits (1024 steps)

So 8 bits is acceptable (like DL), 9 bits is excellent, and above is still better but probably overkill (OpenLRS etc).

Hi kha, DTF UHF and flipflap

I appreciate you guys getting back to me.

@ DTF UHF: Are you saying that FrSky samples three times the rate that Orange Open LRS does?

Cheers

Jase

Hi Gang

Just a couple of questions about obtaining RSSI.

1. Do I need an Electrolytic capacitor?
2. Does the capacitor have to be a specific µF?
3. Does the following image depict the correct connections?

Cheers

Jase

Originally Posted by ilovetoflyfpv

Hi kha and DTF UHF

I appreciate you guys getting back to me.

@ DTF UHF: Are you saying that FrSky samples three times the rate that Orange Open LRS does?

Cheers

Jase

openLRSng samples the controller's PPM at 2MHz using a 16-bit timer but only uses 10 of those bits. The actual code is found near the top of TX.h.

For the RC filter, enter your desired values for the resistor and capacitor into this equation: 1/(2*pi*R*C) If the resulting value (the cutoff frequency) is between 1 and 500 (and the R&C values are reasonably close to those provided by kha) you will be fine. The capacitor does not need to be electrolytic. That diagram does depict the circuit you need.

Originally Posted by DTF UHF

openLRSng samples the controller's PPM at 2MHz using a 16-bit timer but only uses 10 of those bits. The actual code is found near the top of TX.h.

For the RC filter, enter your desired values for the resistor and capacitor into this equation: 1/(2*pi*R*C) If the resulting value (the cutoff frequency) is between 1 and 500 (and the R&C values are reasonably close to those provided by kha) you will be fine. The capacitor does not need to be electrolytic. That diagram does depict the circuit you need.

Hi DTF UHF

Thanks for getting back to me. My electronic knowledge is basic so I'm having trouble following your explanation. At this point I understand that Orange Open LRS has a resolution 1024 while FrSky is 3072. I suppose I simply wanted to know would I notice a difference? I am however keen to further my understanding. Are you saying that both systems are 10-bit but because FrSky samples more frequently the resolution is greater?

As for the RC Filter, what are my desired values? What type of filter is this eg high pass, low pass? Cutoff frequency?

=1/(2x3.142x10x10)
=1/628.4
=0.00159134
*This is not between 1 and 500.

I'm not sure what's going on here?

Cheers

Jase

Unfortunately I don't know how the FrSky system samples and transmits its data, I was simply interpreting what another user said on a different forum. Unless FrSky releases information about their systems, I'm not sure that anyone can come to conclusions about how their system handles data.

The values you put into that equation need to be in ohms and farads, so 10k = 10000 and 10uF = 0.00001 which will give a cutoff frequency of about 1.6Hz.

Hi DTF UHF

I was wondering about k and µF. So I assume a cutoff frequency of 1.6Hz is good (between 1-500)? I'd love to know what's happening here i.e. the significance of this calculation?

As always really appreciate the help.

Cheers

Jase

Sure thing. A resistor and capacitor in that configuration makes a lowpass filter. This can be interpreted as an averaging filter. Imagine the capacitor as a bucket that holds voltage, and the incoming system as a hose that is switched on and off quickly. The bucket will hold a small amount of water that smooths the pulses of water into a steady flow. If the pulses are on for a longer time the output from the bucket will be a flow of a larger amount of water. If the pulses are very short, the flow will be very small. The steady flow is the 0-3.3V signal, and the pulses are the high-frequency PWM which only has values of either 0 or 3.3V.

The size of the capacitor is the size of the bucket. Smaller buckets won't be able to smooth the pulses so the output will also have some pulses in it. Buckets that are too large will average the pulses over a longer time period so the output will lag behind the input significantly.

If you are interested in learning more about how such systems work, I highly recommend this book: http://www.amazon.com/Cartoon-Guide-.../dp/0062731009 it really is a good introduction to physics and basic electrical systems (which are both related through nature) and is appropriate for almost all ages

Hi DTF UHF

I love the book . I'm really interested in learning about electronics. I've recently attended an introductory hobby course where we made a regulated power supply. Unfortunately, there wasn't much in the way of theory which I was mainly interested in. Grasping key concepts in crucial in building knowledge. I suppose it's a little like foundations of a house.

So would your preference be a 10µF or a 100µF capacitor? From your explanation (which was awesome) the 10µF may make the RSSI jumpy while the 100µF may make it sluggish.

Cheers

Jase

10uF and a 10k resistor should work fine as long as the filter has between a 1 and 500Hz cutoff. A capacitor that is much too small, such as in the pF range wouldn't filter the signal very much.

I have a problem when activating telemetry. Despite what baudrate 0,1 or 2 I am running my servo jitters like crazy when telemetry is active. When I disable telemetry the symptom disapears. I am running openlrsng 3.0

Hi Gang

Well I've been busy. I've put together the following;

• Moxon Antenna
• Turnstile Antenna
• RC Filter

I really want to thank everyone for their help. I apologise for the poor video. It's been really wet here and my video system doesn't like it.

Cheers

Jase

Orange Open LRS Open LRSng Test 2 (16 min 3 sec)

Hi, how enabled beacom witout terminal serial connected ?
i try #define DEFAULT_BEACON_FREQUENCY with frequency numerec or channel PMR
but beacon not activate, failsave activate but not beacon
Thank.