Just a heads up to this latest offering from Flytron
http://store.flytron.com/16-openlrs (http://store.flytron.com/16-openlrs)
May be of interest to those who are happy to experiment and dont need plug and play.
Please remember the legalities surrounding the use of this system.
OMG - thats an awesome site! If only I'd paid more attention in the electronics class at Uni!!!
:+
Ooops, seem to have hit the buy it now button.
A very quick look at the code and it seems that it can be configured for 459MHz without too much trouble?
We'll see what it's like in the next week or so...
Nigel.
Hey Nigel,
I downloaded and checked the code - yep, it does seem to specify the current system to 435mhz. This is specified in two places for each the Tx and Rx.
I am SOOOOOO temped to order one for a play, but I already have more Control frequencies than I have models - and as you can see below - I have quite a few of them!
Let me know how it goes though!
Cheers, Nic.
Nic,
Found this for calculating registers (right click and 'save as')
http://www.hoperf.com/upfile/rf22%20register%20settings_revv-v23.xls (http://www.hoperf.com/upfile/rf22%20register%20settings_revv-v23.xls)
Some more resource and tools (near top right) of this link
http://www.hoperf.com/rf_fsk/rfm22b.htm (http://www.hoperf.com/rf_fsk/rfm22b.htm)
I lost my last posting as the server won't take any more attachments :(
Nigel.
Just a thought, would not some of the RF circuitry and SM component values need revision for use on 459mHz?
No other curcuitry is required, but I think that the 433 chip will be at it's limit at 459MHz and maybe requires the 470MHz chip to work efficiently at 459MHz.
Check out the spec:
http://www.hoperf.com/upfile/RFM22B.pdf (http://www.hoperf.com/upfile/RFM22B.pdf)
Nigel.
Had a quick scan of the 70 pages. Looks like spec limit is 453mHz for the item on offer, may/may not go the rest of the way. Wait and see results of his tests next week.
Off topic; Been scanning the 70cm band in my area for the last week and its all but dead. I'm 250ft up a hill with unrestricted view for 10's of miles over populated areas. Using Yaesu FT-60 transceiver and Yupiteru MVT-7000 scanner. Is it just my location or perhaps the norm?
I have my OpenLRS Tx and Rx now and will try to get some testing done over the coming days.
Found a few niggles with it 'as is' but nothing that can't be overcome.
I think it will ultimatley need the fitted 433 module modifying to match the PA matching requirements to run at 459MHz.
I have asked Melih (Flytron) to consider getting some HopeRF 470MHz modules, which are better suited to 459MHz.
Nigel.
Hi Nigel,
I have been in contract wtih Hope, and they have confirmed that the RFM22B 470Mhz module is a slot-in replacement for the OpenLRS module. Unfortunately, the 430Mhz module won't reach 459...
I also have a company that can supply these modules - but min order is 50...
I'm getting a quote anyway to see what the price is... will post when I get further info.
Cheers, Nic.
Hi Nic,
Yep, I saw from the spec of the 2 modules that each is tuned for a certain bandwidth.
The small train of impedance matching components can be changed to suit any frequency on the HopeRF module, but they are pretty small and I have to source the ones I need to get to 459MHz by swapping them out on the 433 module.
I asked Melih to get some 470 modules when he next places his batch order with HopeRF, which he agreed to do, so we'll wait and see...
Nigel.
Hey Nigel,
Swapping the module is one thing - but swapping components on the module... I bow to you sir! :laugh:
Looks like you have it all in hand!!!
Looking forward to hearing about your results - please take loads of photos as well!
Cheers, Nic.
Nigel - I just checked the updated doc's on Hopes website, and it looks like they've dropped the 470mhz module... Not sure if your mate can still get stock, but I thought I'd let you know...
Cheers, Nic.
I asked MelihK the producer of OpenLRS to get the 470 modules.
Maybe I really do have to go down the component swap route.
Have a read of pdf file 'AN435' - PA matching, near the bottom here:
http://www.silabs.com/support/pages/support.aspx?ProductFamily=EZRadioPRO (http://www.silabs.com/support/pages/support.aspx?ProductFamily=EZRadioPRO)
Table 2 on page 3 makes a good read (or not).
Only 10 'ickle SMD components need changing - on each board!
Nigel.
Quick update... (click the images for a larger view - you might need it !!)
Traced out the PA matching network on the HopeRF module (sorry it's my hand sketched layout)
(http://s3.postimage.org/36ajht4lg/Hope_RF_PA_matching_network.jpg) (http://postimage.org/image/36ajht4lg/)
An extract from the AN435 pdf file, shows
(http://s4.postimage.org/2dinnlsh0/Hope_RF_PA_matching_459.jpg) (http://postimage.org/image/2dinnlsh0/)
Here's the bits that need changing (highlighted in the green boxes on the green PCB module)
(http://s3.postimage.org/2ln6qpw/Hope_RF_PA_matching_433.jpg) (http://postimage.org/image/2ln6qpw/)
So, ordered some new 0402 size components (0402 = 1mm x 0.5mm component size) and will endevour to swap out the various ones to get to 459MHz PA matching.
Nigel.
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 :'(.
Wow! Impressive stuff Nigel! I hope your're succesful.
:o
Fantastic / Amazing...
Do you have a PCB/Solder oven, or are you going to solder those by hand?
Cheers, Nic.
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.
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 (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.
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
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.
Eagerley awaiting the outcomes on this :)
Cheers for the heads up Nigel, cold has now subsided to allow my pre-cold stupidity to resume.
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.gif)
http://www.qsl.net/n9zia/wireless/pics/rfprobe.jpg (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.
Quote from: Devonian on June 23, 2011, 11:40:16 PM
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
I have emailed HopeRF. I'll report back.
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.
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
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.
(http://s4.postimage.org/2dinnlsh0/Hope_RF_PA_matching_459.jpg) (http://postimage.org/image/2dinnlsh0/)
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.
I've created another thread specifically for UK use of OpenLRS
http://www.fpvuk.org/forum/index.php?topic=2551.0 (http://www.fpvuk.org/forum/index.php?topic=2551.0)
Nigel.
@ Simon,
I have now found the correct software (firmware) settings to properly generate 459MHz.
Melih's standard code 'forces' the module to stay in the band 430 - 439.9MHz, no matter what is set in the config.h for 459Mhz.
My original RF output at 435MHz measured a healthy 98mW (100 mW) output.
Now, at 459MHz I measure 92mW output.
When HopeRF said the module works 'OK' at 470MHz perhaps in their eyes, a 10% tolerance is 'OK' or 'acceptable'??
How much difference that would make in range is probably negligable, especially if you bin the supplied (430MHz) rubber duck antennas and make properly tuned ones for 459MHz (which I have done).
I left the Tx on a soak test at 459MHz for 5 minutes and the module doesn't even get warm, probably thanks to it's 50Hz Tx rate.
I will have a go at changing the RF matching components and make some more measurements and continue posting in the new thead...
Nigel.