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Old Nov 22, 2011, 06:27 PM
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ISRAEL
Joined Aug 2007
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New Product
U-link uhf lrs

new LRS has been tested /flown tens of hours and now I'm about to order production quality boards. Still have time to change looks and functions if asked.
Because many FPVers today use autopilots andflight controller boards that expect PPM input I've made small board that has single connector to input or output PPM. When power applied the circuit checks the connector for incoming PPM, if signal detected TX function assumed till next power cycle.
If no PPM then board try to init. Wii Nunchuck if found then it is TX again.
If no nunchuck present RX function starts and PPM input becomes output. There are no switches or PC connection, automatic mode selection , to set frequencies and program repeater function connect Nunchuck and input series of clicks using "C" button the same way as some of you programmed RF beacons.
The system works best without PPM - nunchuck is polled 270times per second and as many packets transmitted with frequency hopping each packet.
Telemetry transmitted 4Hz, channels res.1/512, module powered by 1S Li-Po, current drawn 120mA.
With the system 2 pilots can control one plane even if miles apart, the RX can track both remotes and give other pilot priority if 1st pilot has stick centered. You can hand 2nd remote to anyone to fly your plane and overtake control any moment with your controller.
Final board may look a bit different, those can't wait PM me, I have about 20 prototypes that work excellent, you only need to solder 4 wires your own nunchuck connector or use servo plug to input /output PPM and power to fly the boards, $60/each, two identical boards make link.
Telemetry receiver is a standalone module with 2X16 character LCD. I 'll picture it later.
Available modules 400-470, 800-900 and 900-930MHz.
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Last edited by fmkit; Nov 22, 2011 at 06:32 PM.
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Old Nov 22, 2011, 07:06 PM
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Can I know what is the range ?
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Old Nov 22, 2011, 07:12 PM
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ISRAEL
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Quote:
Originally Posted by emadine View Post
Can I know what is the range ?
depends on how high you locate repeater ,
with 3 repeaters in line you can break distance world record
using only 0.1W per repeater
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Old Nov 22, 2011, 07:42 PM
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With just two board, one on quad and one in hand. What is the est range.
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Old Nov 22, 2011, 07:55 PM
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I fly with the module built into nunchuck so wire antenna is normally hanging just 3ft above ground and get 1km 100% packets received and and it starts to degrade at about 1.5km. Similar results getting Flytron, 2 other russian designed systems using the same RFM22B modules. My system is easiest to use and has functionality not seen in other systems, most responsive(lowest latency) of them all and can work w/ nunchuck and multiple repeaters.
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Old Nov 22, 2011, 07:58 PM
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this looks great. subbed.
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Old Nov 22, 2011, 08:10 PM
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If you fly with the nun chuck, is it possible to alter servo throws or do you do that mechanically on the plane?

Thanks

Mark
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Old Nov 22, 2011, 08:18 PM
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Hello fmkit thanks for ur reply. One last qns. A single board can act as a repeater or need two board connect together to form TX/RX set?
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Old Nov 23, 2011, 06:39 AM
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ISRAEL
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Quote:
Originally Posted by mark hitchman View Post
If you fly with the nun chuck, is it possible to alter servo throws or do you do that mechanically on the plane?

Thanks

Mark
yes, nunchuck itself can only config. frequencies and accelerometers zero.
rest of setting done in RX and throws set mechanically.
this way nunchucks easily swapped.

emadine, each board is rx and tx, repeater is simplest function that require no connections other than 1S Li-Po. Just one board makes repeater. It is waiting for packet and transmitting received packet immidiately on the same frequency packet was received cause nunchuck change frequency every packet making room for repeater.
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Old Nov 25, 2011, 06:05 PM
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This is a cool product!
The repeater function is innovative but probably not something most people will use. Anyway imagine putting a repeater on another plane halfway.
Just like OpenLRS, using the term "LRS" gives wrong expectations: You need an amplifier or repeater for U-link to be long-range. I would like to know more about options for amplifier without going to extremes like 7 watts.

Would it be possible to place a repeater nearby with amplification to achieve moderate long range? That could help against a 0.5W signal close to the ground station disturbing the video reception.

What about Rx RSSI?

If you don't mind me asking, how big capacitor did you judge necessary in the aircraft to protect against voltage dips? Do you think tantal is ok?

Quote:
Originally Posted by fmkit View Post
The system works best without PPM - nunchuck is polled 270times per second and as many packets transmitted with frequency hopping each packet.
The nunchuck is polled with 270hz but the Rx can't output PPM this fast, right? Do you have an alternative way of controlling the servos?

Quote:
Originally Posted by mark hitchman View Post
If you fly with the nun chuck, is it possible to alter servo throws or do you do that mechanically on the plane?
I think U-link would go well together with Channel Wizard that can decode PPM to servo signals. Throws, neutral and reversing are adjustable for each servo. The "Eight" version decodes 8 channels. "Mini" decodes 4 channels and has I2C for future features. (Maybe updating channels faster than PPM can?)
Both devices can be daisy-chained to decode different channels in different parts of the plane.
It can also act as PPM encoder (for DIY'ers) to feed the transmitting U-link.
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Old Nov 25, 2011, 07:08 PM
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ISRAEL
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Quote:
Originally Posted by FpvKiwi View Post
This is a cool product!
The repeater function is innovative but probably not something most people will use. Anyway imagine putting a repeater on another plane halfway.
Just like OpenLRS, using the term "LRS" gives wrong expectations: You need an amplifier or repeater for U-link to be long-range.......

I'm sure no other LRS can compete low power nunchuck working with 2-3 repeaters. I'm advanced class HAM used repeaters from the day I got callsign 20 years ago ,

Would it be possible to place a repeater nearby with amplification to achieve moderate long range? That could help against a 0.5W signal close to the ground station disturbing the video reception.

sure, repeater can be placed at any distance

What about Rx RSSI?

wristwatch-like telemetry module outputs RSSI, packets received, voltage, amps, time, stick position, master/slave status and alarms.


If you don't mind me asking, how big capacitor did you judge necessary in the aircraft to protect against voltage dips? Do you think tantal is ok?

Cypress chips and RFM22B can operate down to 2.4v supply, normally I combine UBEC and BEC voltages with diodes so flight-controller functional while ESC plugged or not. 22uF cap.is enough.


The nunchuck is polled with 270hz but the Rx can't output PPM this fast, right? Do you have an alternative way of controlling the servos?

I have 3 types of flight-controllers that have been in use for 2 months and completly tested. They interface nunchucks only, because normal remotes don't have enough channels to control gyros, cruise, lights and fireworks igniters, multi-presets pan/tilt, multimaster,power LEDs.

I think U-link would go well together with Channel Wizard that can decode PPM to servo signals. Throws, neutral and reversing are adjustable for each servo. The "Eight" version decodes 8 channels. "Mini" decodes 4 channels and has I2C for future features. (Maybe updating channels faster than PPM can?)
Both devices can be daisy-chained to decode different channels in different parts of the plane.
It can also act as PPM encoder (for DIY'ers) to feed the transmitting U-link.

PPM is slow and limited to few channels, I'm not using PPM at all
Look here about using nunchuck with the flight controller
There are more key combinations that I don't remember myself, the nunchuck can transmit packets as well PPM to use UHF walkie-talkies as RX.

Here some old pictures, tomorrow I make better pics.
1st version of telemetry module:

1st version RX:


diy fun:
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Old Nov 25, 2011, 07:55 PM
Crashomatic
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need supply of RXs on your paypal page ;D
isee you're going to produce quite a few, thats cool
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Old Nov 28, 2011, 01:45 PM
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Thanks for your reply, fmkit.
If you want to spread the system, PPM is good since it's in common use. The relative lack of speed doesn't matter for everyone. Certainly only a few channels benefit from high update rate.
Have you published any info about your flight controllers? I can't find any. Is it the pic "1st version RX"? But that looks integrated with the radio module.
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Old Jan 07, 2012, 12:48 PM
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I agree that PPM is not the best transmit scheme but at the same time many people probably do not want to learn to fly with Nunchuck controller if they are very comfortable with standard radio transmitter.

Would there be some way to wire at least the four stick potentiometers from a regular TX directly to Nunchuck board, bypassing pots in the Nunchuck controller somehow?

Or do you have any other thoughts about integrating this system with a standard RC transmitter? I think the idea is brilliant and well executed, I just don't want to fly with a Nunchuck.


Luke
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Old Feb 21, 2012, 10:59 PM
Crashomatic
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Hey Peter,

I was wondering, now that the page is up: what advantages do you get with the 423mhz SAW filter (video interferences?), and is it low or high pass?

I'm actually going to get one once you reply to that :P

also, you should make a price rx+tx :P

Thanks!
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