Open LRS

[ORCA]

The very best of luck :o! For me with the eyesight you end up with in your mid 60's and 'sausage' fingers its a complete non starter :'(.

[simondale]

Wow! Impressive stuff Nigel!  I hope your're succesful.

[Swissnic]

 :o

Fantastic / Amazing...

Do you have a PCB/Solder oven, or are you going to solder those by hand?

Cheers, Nic.

[Devonian]

All solder work will be 'by hand'.

I made a soldering iron tip into a de-solder tool suitable for 'picking' the 1mm x 0.5mm components off the board - works well too.
It's just a 2mm solder tip with a 1mm slot in it - drop it over the component and simply lift it off the PCB as it is a snug fit in the 1mm slot in the iron tip.  Once unsoldered off the board, pick it out of the tip with tweezers.
Rinse and repeat!

I can solder the new bits on without too much dificulty as well.

Parts arrive early next week.

I have to use some of those magniying head goggles though !

Nigel.

[Devonian]

Anyone any good at writing software for Arduino?

I need a bit of 'special' software to produce a single Tx frequency.
That is, not the 'normal' 50Hz and channel hopping.

Read all about it...
http://forum.flytron.com/viewtopic.php?f=7&t=63&p=346#p346

Any help would be gratefully received as it benefits UK users the most.

I have all my components to swap out, but need the software before committing iron to board!

Nigel.

[simondale]

Hi Nigel,

It sounds like you've made good progress.  I wonder why you want to remove the FHSS stuff?  Is that just for testing?  

I know the Ofcom rules don't say anything about it needing to be FHSS on 459MHz but I see that as a great feature of modern radios and it would be fantastic to have that available on 459MHz (IE non-2.4GHz) too.

All the best

Simon

[Devonian]

Hi Simon,

I only want to stop the FHSS (channel hopping) for testing.
I want to check the actual programmed frequency & power output (pre-set at 435MHz & 1 hundred mW <-- why does the forum change my 100 m w to Video???) before changing the onboard components to properly match 459MHz.
Once I have checked the original freq, then I will mod the boards to 459.
Once I am happy they work correctly, I'll install the 'standard' software, which is actually Frequency Hopping and not full blown FHSS (Frequency Hopping Spread Spectrum) as it only hops on 3 (or more if you want) pre-programmed channels.

My little frequency counter/power meter is totally confuzzelled by the channel hopping and 50Hz Tx rate.

The HopeRF unit appears to Tx at 50Hz so as not to impose 100% duty cycle to the PA stage with the subsequent potential heat build up (and maybe thermal shutdown protection?).

The HopeRF module that the current OpenLRS ships with is only rated to 453MHz.
What we (in the UK) want is the HopeRF module for 470MHz as 459MHz is within it's design parameters.
Unfortunatley, the modules have to be bought in quantities of 50+, which Melih is looking into on his next order with HoperRF, but I'm inmpatient, plus I already have the 435MHz Tx & Rx and I like a challenge (not!).
We need more UK users to buy into this and bug Melih into getting a batch of 470 modules in stock ;)

I have all the components to swap out on the module, but need the 'special' software to properly check things out before I commit my soldering iron to the boards.

The OpenLRS has such potential, I'm surprised that no-one else in the UK seems to have taken it up.
The Rx can be made to become a transceiver (Rx & Tx together, for Telemetry perhaps?) and already has the interface for i2C devices (IMU based gyro/stabilisers (Wii/Nunchuck boards), Barometric readers, OSD etc etc).

HTH.

Nigel.

[Funky Diver]

Eagerley awaiting the outcomes on this :)

Cheers for the heads up Nigel, cold has now subsided to allow my pre-cold stupidity to resume.

[Devonian]

I've done nothing to this for a while as I'm now a one week old Grandad and my ma-in-law is not very well (we are nearly full time carers at home).

Melih has now written some code in v1.7 that allows you to fix the Tx freq to one channel (no hopping).
I made some measurements with a simple RF probe/watt meter, similar to this:
http://www.qsl.net/n9zia/wireless/pics/rfprobe.gif
http://www.qsl.net/n9zia/wireless/pics/rfprobe.jpg

Oddly, when checking the output voltage at the probe, it stayed almost flat from 430MHz to 470MHz, which suggests that the output is around 100 mW throughout.
However, due to the way the RF PA works, I reckon the spurious emissions will be well up at around 460MHz and above - hence the need for the correct matching network to properly control this.


More as I get time...

Nigel.

[simondale]

Unfortunatley, the modules have to be bought in quantities of 50+, which Melih is looking into on his next order with HoperRF.

That seems strange. You'd think they'd be able to provide samples at a higher price for testing.  Do you know the exact model number that we need? If so can give me that I'll see if I can find some samples from them/ somewhere else.

All the best

Simon

[simondale]

I have emailed HopeRF. I'll report back.

[Devonian]

Hi Simon,

As you are 'in the trade' you are more likely to get some samples from HopeRF, whereas an end user will get nowhere.

We need the 470MHz module as opposed to the 430MHz module that is currently in the OpenLRS.

If you are able to gets some, let me know and I'd take 3 or 4 modules as fitting them would be a relative doddle.

Cheers,

Nigel.

[simondale]

Hi Nigel,

I got this reply just now:

Dear Simon Dale,
 
You can directly configure 470Mhz using RFM22B-433 and RFM23B-433.  Our module support 433,868 and 915 band, each band has configurable frequency range. We have made the test on 470mhz, all RF performance is ok.
 
Pls find the pricing below:
MODEL   description   5K   1K   sample
RFM22B-D    20dB transceiver module   3.24   3.54   5.40
RFM22B-S1    20dB transceiver module   3.24   3.54   5.40
RFM22B-S2    20dB transceiver module   3.54   3.84   5.70
　   　   　   　   　
RFM23B-D    13dB transceiver module   2.64   3.04   4.85
RFM23B-S1    13dB transceiver module   2.64   3.04   4.85
RFM23B-S2    13dB transceiver module   2.94   3.34   5.15
 
delivery: ex-works
lead time: about 4 weeks if stocks unavailable
payment term: T/T in advance
note: 1. for any amount of payment transfer by T/T, the customer should pay
USD30 as bank charge
        2. for transfer money by Paypal, customer need to pay 5%*value for
paypal transaction fee
 
Do you want to order 5pcs for each module? BTW,demo kit is available also, USD80/set including 2 units demo board and 2pcs DIP module.
 
From your email,I am not sure if you tested this two modules before?
 
Pls provide your company address and telephone no.,I'll make a P/I for your payment.
-------------------------------------------------------------------------------------------------------------------------
RFM50 is 20dB transceiver module using SOC chip, its cost is cheaper than RFM22B+external MCU.   
a 500mW transceiver module based on RF23B chip will be released very soon.
pls let me know if you are interested in above modules.
Best regards,
Elsa
Hope Microelectronics Co.,LTD

[Devonian]

Hi Simon,

Interesting...

A couple of post back, I commented that the RF output I measured seemed to be pretty flat from 430 - 470MHz, indicating that the module could indeed 'work' at 459MHz (I calculated RF out at 98mW, which is good enough for the claimed 100 mW).

My main concern is with actual signal quality as well as signal quantity, because from the datasheet AN435, it indicates that the RF matching stages are different for the 2 frequencies.



Maybe I'll go ahead and fire it all up at 459MHz and see how things work out without modifying the module.

Thanks for posting HopeRF's response.

So, everyone should now go ahead and get OpenLRS fired up on 459MHz and stay totally legit!!!

Nigel.

[Devonian]

I've created another thread specifically for UK use of OpenLRS

http://www.fpvuk.org/forum/index.php?topic=2551.0

Nigel.