thUndeadMod v3.4 - openLRS S**T just got real :)

[FPVSimon]

Surely 10kHz steps would be:-

459.100
459.110
459.120
Etc

????????!

[Devonian]

Surely 10kHz steps would be:-

459.100
459.110
459.120
Etc

????????!

Correct, BUT, that doesn't conform to the allowed 459MHz channel spacing of 25kHz (or 50kHz due to the 10KHz steps).

Nigel.

[Jumpy07]

Nigel,

I am no programmer.. and have been trying to understand KHA's version of the code that I am running..

One thing I am struggling with is  ..how the channel hoping numbers relate to the frequency based on start freq..

I rightly or wrongly assumed that it was the same as Thundead's code as that what it was based on..

According to KHA, the bandwidth is 25Khz +/- the carrier.. 

So should really start at 459.125Mhz

Ch1 - 459.125
Ch2 - 459.175
Ch3 - 459.225
Ch4 - 459.275
Ch5 - 469.325
Ch6 - 459.375
Ch7 - 459.425
Ch8 -459.475 Cant use as would take upper freq above band allowed. ?

[Shikra]

Nige l - do you know ...

Is it mandatory to stick to that schema? or is it more  recommendation / best practice?
Are you allowed frequency hopping across the band?

I started looking at openuhf for first time last night as I have had soem modules kicking around. Looking at the code I think config for us is as follows...

I think its base frequency of 459100000 or 459125000
Hopping channels of  5,10,15,20,25,30,35
Does that seem right? I dont think channels are 1-8 as mentioned earlier, but I'm new to OpenUHF - purely looking at it from code / sheet

[Shikra]

Just saw last post - so bandwidth used is 25k ? thats interesting, I would have thought it would have been less than 10.  Thats quite wide. = better range though ! I assume thats adjustable?

And assume thats why the reference to not using the last ch. 

[Devonian]

@ Shikra,
I don't think it's manadatory to stick to the schema other than it would be 'polite' to existing fixed channel users (there are a few).
However, for frequency hopping, I guess it doesn't really matter, even if you use the whole band.
From what I remember of the early firmwares, the hopping of 5,10,15,20... etc seems right.

@ Jumpy,
I'm no programmer either!
I have been following kha's code on RCG, but I don't have any of my gear available at the moment as it is in storage during my house move/major refurbishment.


I would have imagined a bandwidth of less than 10kHz as well, but even this is programmable, I believe?
Even a deviation of 12.5kHz would give the 25kHz channel spacing (for fixed channels), leaving 459.475MHz still useable.
If we were to ignore the current schema and go for 10kHz 'channels' combined with hopping, most likely nobody would know we were there.

RCG threads
http://www.rcgroups.com/forums/showthread.php?t=1782034
http://www.rcgroups.com/forums/showthread.php?t=1778553
essentially Flytron's hardware

Nigel.

[Shikra]

Thanks Nigel I'll have  read through those threads. Another one to start following... just what I don't need :)

I had a quick look at the code and it looks like the peak bandwidth deviation is fixed at +/- 15khz from carrier .....

[Devonian]

Hehe - did you know Melih has released some Wii copter code for OpenLRS
http://forum.flytron.com/viewforum.php?f=7&sid=4c67cbb03c290def631fa0425f7d94fd

http://code.google.com/p/openlrs/downloads/list

Sorry, more stuff the read   ;D

Nigel.

[Jumpy07]

Ok,

Done some more testing using the Spectrum Analyser...  So should really start at 459.125Mhz.. and to stay in band and recommendations.. channels recommended below..

Ch1 - 459.125
Ch2 - 459.175
Ch3 - 459.225
Ch4 - 459.275
Ch5 - 469.325
Ch6 - 459.375
Ch7 - 459.425

//######### TRANSMISSION VARIABLES ##########
#define DEFAULT_CARRIER_FREQUENCY 459125000 // Hz startup frequency ---- FOR UK RECOMMENDED TO CHANGE TO 459.125MHZ AS SHOWN 459125000

//###### HOPPING CHANNELS #######
// put only single channel to the list to disable hopping
#define DEFAULT_HOPLIST 2,7,3,5,6,4 ---- CREATE RANDOM CHANNEL LIST OR SET TO SINGLE CHANNEL, RECOMMEND SPREAD CHANNELS - NOTE to keep in UK legal and recommended band - use Channels 1-7 only

[Shikra]

@Devonian - I'm not looking.... yet!

@Jumpy - can you confirm the channels on the analyser. From the code I can't see it being set to 25khz spacing. To me it looks like default as can't see it being set differently unless in bind or beacon mode.

so if set a tx with a base frequency of 459.1 and a single channel of 15 in hopping, I would expect to see 459.250 on the scanner


I just tried a scanner here, but get nographs on the screen. Used stock code, shorted out pins 3+4.
Prob me being thick....
Seems to connect, get a couple of flashed on usb prog.

[Jumpy07]

Had a look at the code.. but not smart enough to understand it.. 

KHA posted on RCG that its 25khz either side.... this is with my settings as above. (Channels 2-7 in hop)   

[Shikra]

I must have read it wrong .. or there is something else transmitting on that frequency range!!


Thanks for posting. Will see if I can get the scanner running, have a play and take a more indepth look at the code. I'm just not seeing the channel spacing of 50hz being programmed anywhere!

I'd be inclined to run it with a few different single channels - to prove.

See if I can get my scanner working later

[Shikra]

Right guys, I've had a look at this from the code perspective -

#0 you MUST always clear EEPROM for any changes to frequency etc. otherwise you will not see correct results ;) Having read the code, previous weird scanner results now make sense!
#1 set the correct default carrier and channels
#2 the default channel spacing is 60khz.. (explains jumpy07s slightly off scan)
#3 the deviation is 30khz = bandwidth of 60khz


So for us in the UK to be legal, use recommended aircraft band and play "nice" with other users as Nigel says....., this would be my recommendation.


in openlrsng.ino, set the following

//######### TRANSMISSION VARIABLES ##########
#define DEFAULT_CARRIER_FREQUENCY 459100000  // Hz  startup frequency
or
#define DEFAULT_CARRIER_FREQUENCY 459125000  // Hz  startup frequency


//###### HOPPING CHANNELS #######
// put only single channel to the list to disable hopping
#define DEFAULT_HOPLIST 1, 2, 3, 4, 5, 6, 7


#2 in common.h, change:
   spiWriteRegister(0x7a, 0x06);   // 60kHz channel spacing
to
   spiWriteRegister(0x7a, 0x05);   // 50kHz channel spacing


#3 in binding.h, change:
   { 4800,  50000, 0x00, 0x1a, 0x40, 0x0a, 0xa1, 0x20, 0x4e, 0xa5, 0x00, 0x1b, 0x1e, 0x27, 0x52, 0x2c, 0x23, 0x30 },
   { 9600,  25000, 0x00, 0x05, 0x40, 0x0a, 0xa1, 0x20, 0x4e, 0xa5, 0x00, 0x20, 0x24, 0x4e, 0xa5, 0x2c, 0x23, 0x30 },
   { 19200, 25000, 0x01, 0x06, 0x40, 0x0a, 0xd0, 0x00, 0x9d, 0x49, 0x00, 0x7b, 0x28, 0x9d, 0x49, 0x2c, 0x23, 0x30 }
to
   { 4800,  50000, 0x00, 0x1a, 0x40, 0x0a, 0xa1, 0x20, 0x4e, 0xa5, 0x00, 0x1b, 0x1e, 0x27, 0x52, 0x2c, 0x23, 0x14 },
   { 9600,  25000, 0x00, 0x05, 0x40, 0x0a, 0xa1, 0x20, 0x4e, 0xa5, 0x00, 0x20, 0x24, 0x4e, 0xa5, 0x2c, 0x23, 0x14 },
   { 19200, 25000, 0x01, 0x06, 0x40, 0x0a, 0xd0, 0x00, 0x9d, 0x49, 0x00, 0x7b, 0x28, 0x9d, 0x49, 0x2c, 0x23, 0x14 }


Note - dont bother trying to use the scanner to verify hopping through all channels. Its not accurate enough.
Try using 2 of the channels at a time in the default list and a 1500 sample. It will show up well then.

[Shikra]

BTW - that was to go by the book. Not necessarily the optimal performance I guess - but Nigel can probably advise better !

[Devonian]

Good work Gary - thanks.

I really don't know about the channel spacing.
In reality it's a specification from the past where you only built R/C radios with a single, fixed channel.

Personally, I can't see an issue with using smaller 'spacing' providing hopping is used.

I've emailed the UKRCC to see how they feel about 10kHz 'channel spacing' for FHSS on 459MHz.
http://www.ukrcc.org/459mhz.html

It might pay to start a whole new thread as this one is for thundeads code and these more recent codes are quite different.

Nigel.