Scale Soaring UK

As a futaba user, 8FG, i have no telemetry!
So rather than spend a bunch on a new transmitter, i thought i would try and build by own system.
So i used a couple of arduinos, one on board and one on the ground.
These are available cheaply on ebay from china for a couple of quid.
I then sourced a couple of 433Mhz transmitters and receivers and a display.
I created a simple voltage divider to ensure that the onboard ADC, of 5V can input a range of 0-20V to measure my battery system. The divider is a 300k and 1M resistor giving a scaling factor of 4.38, so i can read up to about 21.9V without damaging the on board ADC.
Both receiver and transmitter will run on a 3s Lipo.
A little bit of programming using the adruino programmer on the PC and i have a transmitter and a working receiver !
I have tested the range on the ground and i works to well up the street to about 20m plus, so i am hopeful that i can receive some useful telemetry information from on board the model. I also hope that i can add other useful stuff like later GPS, speed, height etc once i have proved the range is acceptable when flying.
I also hope that the 433Mhz transmitter does not interfere with my 2.4Ghz control. I may have to do some extensive range testing on the ground before i risk it in my test model of choice, my swift S1, then my 4.2M asw20.

Arduino transmitter.
The LIPO is power for the transmitter. The Transmitter is bottom right on pic. Eneloop is simulating the receiver battery, in the model i simply plug the plug into a spare port on the reciever. Im using a large arduino (mega) at the moment, i will use a nano ardiuno which is a fraction of the size and weight.

Base station.
I can tell if the link is active with the dot on the right.
It disappears after 1s if there is not a valid voltage received.

Cost so far is about 3 quid for each ardunio 1 quid for the transmitter and 1.62 quid for the display, a few bits of cables and leads.

Sorry links not working, grr

Jimbo, I used the Wireless Co-pilot 433 mhz Vario and Current sensor with both Spektrum and Multiplex 2.4 systems and there was no interference with the 2.4 systems, so i don't think you'll have any issues in that respect.

The WCP current sensor worked well in the models I used it in, the vario was a bit more hit and miss in a glider as the range was much less than the Multiplex M Link telemetry systems.

BTW have you seen the Opensensor forum, I've built their Vario (bariometric sensor and ardunio) to go with my M Link stuff, but for somebody clever than me it could be adapted to work with a 433 mhz transmitter i'm sure.

Franks, good to hear no interference. Im abit worried about the range as the transmitters according to the internet are a bit limited to a few hundred metres. Im not sure how good it will be if at all. If it runs out of range at 20ft, there are more expensive transmitters available.
No ive not looked at anything online, just googled for a few bit on the arduino so far.
Im sure if i can prove the concept, there is a bucket load i can do once i get a gps on board, this looks pretty straightforward too. I have a ram card to which it can write the gps co ordinates rather than transmit and analyse later to google maps if i desire.
Next task will be to read the speed and height somewhere, perhaps from the gps or some air sensor of some sort, more research required.
Once i start transmitting more data, i will need to write some sort of protocol (yawn), i can put the code up so far if anyone is interested (its arduino C).

Jimbo,
I looks as if most of the low end 433MHz links are intended for very short range remote switching (e.g. Garage doors etc.) but you can get modules that will work up to 300m or above if you look around.
Robotshop.com have a 2km link pair, but these appear to be very low data rate types (again primarily intendedy for simple on/off control).
However, Futurelec.com market a range of Tx/Rx modules, although with very little documentation to explain how to use them!
It appears that you are likely to need a link budget of approximately 120dB to achieve a 2km link range (antenna dependent) at 433MHz.
Good luck.

Jimbo,
It looks as if rfsolutions.co.uk have 433MHz transceivers which should be capable of 1-2km.
Their site also has good documentation which can be downloaded, together with example projects, albeit with Microchip devices, but they will give a starter for 10.
Their transceivers are also rather cheaper at just under £5 each.

Jimbo,
Just looked further at the rfsolutions.co.uk website and there is a download available for the Zeta transceivers which gives you an Arduino library for the Zeta units plus sample Tx & Rx end sketches.
Thus I think I may well try a couple of the Zeta modules for general RF link experimentation as their range & data rates make them useful for a number of purposes.
Their "Small Outline" package size of 16x16mm with thro' hole connection pads is also handy.

Having now looked at the ZETA units in more detail, I wouldn't advise going for these as they really also need a separate Codec chip to be able to control them from an Arduino type platform.
However, I am now looking at the RFM69CW units available from Hobbytronic which have similar RF characteristics and can be controlled directly from an Arduino.
A much more compact implementation though, is the tiny Moteino devices from LowPowerLab as these provides both the same RFM69 transceiver chip and an atMega328 (as in Arduino Uno) in a single tiny package about the same size as an Arduino Nano. (They are effectively another Arduino clone, using the Arduino IDE and libraries). There is also a RFM69 library and lots of home automation/networking sketch examples available for these units.

By the way, the U.K. Radio regulations allow the use of 433/434MHz for airborne model telemetry up to power levels of 10mW (+10dBm) but check the latest Regs. for detailed restrictions.
Note that a 1/4 wave aerial length for 433MHz is 173mm, so this needs to be kept straight in the fuselage.

Or you could just but a Taranis, and make life easy....

Sorry, but I had to say it.



BC

[quote="Barry_Cole"]Or you could just but a Taranis, and make life easy....

Sorry, but I had to say it.



BC[/quote]
I was wondering when the taranis quote would appear !

Anyway, ive done nothing as i think i blew up an arduino with my voltage divider, when i connect to a lipo rather that the USB, i get 6.5V across the 5V pin, currently ive ordered a replacement nano and waiting for the slow boat from china to bring it.
I can still test it on board but my reference voltage is no longer 5V it varies with the state of the lipo (which means my read voltage is screwy), but ive not had the inclination anyway in the cold north and easterly winds.

[quote="Peter Balcombe"]
Note that a 1/4 wave aerial length for 433MHz is 173mm, so this needs to be kept straight in the fuselage.[/quote]
I tried it before an aerial was added and after the correct aerial was added - the range went from 2ft, to in the order of 50m (along the ground outside). Im hoping to an overhead object range will be improved further.

Jimbo,
You will get best performance if the antenna wire is at 90 degrees to the board ground plane, thus the wire should be sticking straight out of the board connection pad hole. Also, as for our normal TX antenna, the maximum signal strength will be at 90 degrees to the axis of the wire/antenna rod as it radiates out in a doughnut pattern around the antenna axis.
(Think of a ring doughnut slid over the antenna & the radiation pattern being similar to the shape of the doughnut - highest where the doughnut is thickest!!)
This is why 2.4GHz aerials should always be cranked at 90 degrees - to give maximum radiation in the likely direction of the model.
If you now get 50m range with direct line of sight signal path (no walls/physical obstructions in the way) then I wouldn't expect too much more in the air.
Remember that the 433MHz units you are using are quite low Tx output power & Rx sensitivity and intended for the sort of range you are now achieving. This is why I mentioned higher power/sensitivity alternatives earlier.

Using a telemetry equipped radio may not be that expensive an option at the end of the day as you should at least get a proven setup with off the shelf sensors etc. However, there is always the challenge of brewing your own

Using a telemetry equipped radio may not be that expensive an option at the end of the day as you should at least get a proven setup with off the shelf sensors etc. However, there is always the challenge of brewing your own

See post below....

Sorry Jim.



BC

Barry, Why would I want to change my radio when I am completely happy with the one I have at he moment, I have many receivers, i will save 400 quid if I don't replace(tx plus enough receivers) and as I have detailed above I can make my own for a few quid!

It worked for me...



BC

Test bed will be swift S1. Its gonna fly nose heavy, but i have it set up with rearward CG anyway so, should be OK.
New Uno fixed the problem with the voltage divider, now reading bang on.

Good luck Jimbo,
It will be interesting to see what airborne range you get.
Peter

Hi peter, I'll be estimating the range as its simply battery voltage, no altimeter. I should be able to get a rough approximation based on model size, tbh large models at Aggies spec out at 800ft max, wont go higher in the slope lift, itll be fact finding mission to see if with the current radio set it will be usable. The general idea is to get to a decent altitude and see it we still receive. Model is about 2,8m span so I think if I spec that it'd be 400ft. Starting looking about for a GPS, for speed and altitude measurements.

Jimbo,
I hope I am not too late, but I assume that you will do normal R/C range checks before you try to fly with your telemetry test setup.
Do the check both without the telemetry transmitting, then with, to see whether there is any impact on the R/C Rx when this is operating on minimum signal.
I hope to range check my higher power 433MHz test setup by the end of this week.

Jimbo,
Managed to carry out a basic range check today using two RFM69CW 433MHz modules sending 10 byte payload packets at an RF data rate of 9600baud & using simple 173mm wire monopole aerials at each end.
With this setup, I got successful data packet reception and Acknowledge loop up to 300m range with clear line of sight transmission over flat ground. Both radios at similar height of just over 1m & both aerials in same axis (vertical).
The RFM69CW devices push out 13dBm (20mW), but there are also physically identical RFM69HCW devices available which push out 20dBm (100mW). Receiver sensitivity is down to -118dBm depending on RF bit rate.
Range will be better with a full dipole aerial.

I have also spotted that a UK outfit called HASNET sell very small bare PCBs for about £1 each, which take both a RFM69 module and an atMega64/328 DIL processor, so that may be an alternative to an Arduino Mini plus RF device.
Peter

Is this the one?
http://www.hobbytronics.co.uk/rfm69cw-w ... 7QodHPMHow

Hope to get a fly soon, winds shifting back SW, so just hoping on a clear not too cold weather window.

Jimbo,
Yes, that is the one, although I went for the breakout version at just under a tenner each in order to ease interfacing to an Arduino Uno as the breakout module has the relevant interface pins on a 0.1" pitch and includes both 3.3v regulator and level conversion, making it 5v Arduino compatible.
By the way, I have just fitted SMA jacks to my breakout units (although not specifically designed to do this), so can now fit alternative/commercial antennae.
The 14 pads on the standard module are on a 2mm pitch.
That webpage gives you links to the data sheet, the RFM69 Arduino library and a sample sketch that works straight away on an Arduino rather than the Moteino (Arduino clones with built in RFM69 + flash chip) as the standard LowPowerLabs sketches assume the presence of a flash chip. However, the sketches are easy enough to modify to delete the relevant flash library bits.
The library is good as it allows you to control almost all aspects of the device if you want to.
The library device initialisation default is to use FSK modulation & packet transmission with a RF bit rate of 55,555bps.

It will be interesting to see what you get with your existing setup as a first step.

Very impressive AJH,
The Manchester encoding system gives a guaranteed logic level transition on every data bit & can be used for automatic data clock recovery at the receiving end, but also gives smaller DC offset variations on the received signal (as there are as many short term highs as lows in the data stream), thus making it easier to reliably decode the data stream.

Thanks for the tip on the FRSky SPort protocol. I had just googled it and there are several leads - including an Arduino library available on GitHub which Jimbo may want to look up.
Having the ability to use the range of commercially available sensor units would be a big bonus.

Currently i do not use a protocol. Currently just transmitting a float. Quick n dirty. Using virtual wire and the LCD driver that's all.
If it is successful regarding the range, the plan was to add the GPS write some proper code.
Nice ajh, Some electronics in there. Is that just four the receiver?

All this talk of FRsky... I have a 9xii currently in the garage, would i be able to get the 9xii to display the telemetry information from various sensors, if i buy this modeule? Or is only for half dulplex ie out to the glider, ie does the 9x2 provide a method to show the telemetry data?

https://www.t9hobbysport.com/frsky-djt- ... ter-module

Im guessing the tx doesnt have the facility to display the data?

EDIT - Just read that RCG thread above

I use a FrSky X8R telemetry enabled receiver and a FrSky DJT JR module with pins on the back, into which I can plug one of the FrSky FLD-02 telemetry displays
IIt could be done with this
http://www.brchobbies.co.uk/catalog/pro ... ts_id=1485
I think i need to check and see if the 9x2 still works.

Jimbo,
I seem to recall that it is possible to upgrade the 9x transmitters to be able to change the firmware (say to OpenTx) and also to change the inbuilt RF unit to an FRSky XJR module. I think that the XJR module then allows 2 way operation, but only in D8 telemetry mode. I can't recall what happened about telemetry data display.
I think I upgraded my old unit using a Smartie parts module to upgrade the firmware and take the XJT module.
Try googling '9x upgrade'.

AAAAAAAAAAAAAAAAAAAAAAAAAhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh



BC

Jimbo,
I have just reminded myself what I did when I upgraded the 9x transmitter!!
I added both the programmer and telemetry upgrade options & made this easier (with the solderless method) using two SmartieParts products (Programmer & TelemeryEZ - now replaced by an all in one board at $70!.
The programmer allowed OpenTx to be loaded & the telemetry option replaced the inbuilt Tx with a FRSky XJT unit plugged into the standard module slot.
The mod then used the serial data XJT connector on the rear of the module to get at the telemetry data, which was fed back into the 9x to the Smartie Parts module for display on the normal LCD.
I know that I used this successfully with an FRSky X8R receiver and altimeter sensor - although no voice/audio output.
However, although this gave a much more useable system with telemetry, the switches/pots available on the 9x were a bit limited, so stuck to my Futaba FF9 + FRSky modules without telemetry until I got my hands on a Taranis (settle down Barry!!)

I think barry won't be happy until I buy a taranis (which I won't lol ).

jimbo wrote:I think barry won't be happy until I buy a taranis (which I won't lol ).

In the end you will.......

BC

I finally got round to testing this out in the swift. Winds light 8mph so ideal. The range is excellent right above my head. I probably up to 300 to 400ft. However once I s started to fly away the signal was quickly . Obviously as you fly away the distance increases for the same height, ie trig.. so I flew low and farther out, signal still lost even though distance was less than 300ft.
Pity, it's usable but as mentioned you'd need to fly overhead to get a reading. Better than landing I suppose. Gonna put one together with a nano, for the asw 20.

Jimbo,
Remember that the radiation pattern of your aerials will be doughnut shaped, with maximum radiation/receive sensitivity at right angles to the length axis of the wire, with minimum out the ends of the wire core centreline.
Thus, if both your aerials are in the horizontal plane, you will get maximum range with the receiver above you (aircraft aerial axis at right angles to your ground aerial axis, but as the aircraft goes directly away from you, your position relative to it will reduce from 90 degrees with respect to its antenna wire length axis, to near end on, thus into the minimum strength area.
If you fly the model across the slope, or in a circle around you, you should be able to replicate the overhead range.

In practice, I would have thought you are doing pretty well to get 300ft with the simple low power modules.

Yes, come to think of it i did have the RX wire laid flat on the ground. So some sort of freestanding item is probably needed, would somthing like this improve reception.
http://www.ebay.co.uk/itm/Antenna-433Mh ... SwSgJXNwRg
I was surprised the range in the outward plane, ie forwards with the aerial flat was extremely poor compared to the striaght up range. I mean like less than 50ft.

Taranis!!!!!!

BC

@Barry - Behave!!

These nanos are seriously power in tiny packet, with a 2s mini lipo, whole lot will fit in a matchbox.

Jimbo,
I was forgetting that you had the Tx in the plane & Rx on the ground, but the antenna radiation pattern info is still relevant.
I am no antenna man, but I don't think you really want the Rx antenna right on the ground, but at least a couple of feet or more above it.
As I said before, you need the two aerials to be parallel to each other (either both horizontal, vertical, or the same angle in between) for best range.

The main difficulty you will have with fitting any commercial antenna, is the lack of a good 50 ohm impedance connection to your board(s). You really need a matching SMA connector & in order to achieve good impedance matching (& therefore avoid sensitivity loss) you also need a 50 ohm RF connection to this. If you just cut off the cable connector then you are likely to get an impedance mismatch of some kind, hence losing efficiency. Note that the 50 ohms is an AC impedance at 433MHz, not a DC resistance!!
A point to note with commercial antennae is that not all will give you what you might expect.
This tends to be the case with 'rubber duck' types which are shorter than a 1/4 wavelength. The shorter length is often achieved by winding part of the aerial as a coil (similar to that in link picture) although hidden inside a plastic casing which, whilst using a 1/4 wavelength long wire, usually trades off antenna efficiency for compactness and robustness.
The linked antenna states a +3dB gain, but relative to what?

[quote="Peter Balcombe"]Jimbo,
Remember that the radiation pattern of your aerials will be doughnut shaped, with maximum radiation/receive sensitivity at right angles to the length axis of the wire, with minimum out the ends of the wire core centreline. ..........
If you fly the model across the slope, or in a circle around you, you should be able to replicate the overhead range.[/quote]

Correction:
Forget the flying in a circle bit as you should only get good range in two areas (say directly in front or directly behind) when the two antennae are parallel to each other! Worst range likely to be at 90 degrees to those points, when looking at ends of antennae.

Jimbo,
An update on 433MHz module range tests.
I have achieved approx. 300m with RFM69CW transceivers (20mW output) and 900m with the 'CW' replaced by a RFM69HW (100mW output) at the sending end.
Measurements were conducted with a simple 1/2 wave dipole at each end, operating at 433.0MHz, sending 10 byte data packets at 9600 baud data rate. Both antennae in horizontal polarisation and in clear line of sight with each other.
Range will obviously be less in each case with a shorter monopole antenna.
The RFM69 modules are only about 30mm square, so the antenna is the largest component at 165mm long for a monopole & 330mm for a centre fed (non folded) dipole.

Or you could just buy.....................................



BC

So have I.
However, i always like to help where I can!

I sorta lost interest, been xmas, good flying winds etc. Plus I can just check my batteries on my battery checker ...

Firstly may 2021 be all that the model soaring folks could hope for|
Many years ago in the annals of history there once was a thread referencing the home cooked vario telemetry. Being in a similar position to Jimbo and not really wanting to ditch a perfectly good Futaba set of gear in favour of the ubiquitous Taranis.
What was the end of the story Jimbo?
Did you get a system up and running?
Is there a commercial standalone system I can add to mine?