HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Yesterday, 11:37 PM
Registered User
typicalaimster's Avatar
United States, CA, San Diego
Joined Jan 2005
5,368 Posts
Quote:
Originally Posted by changosurf View Post
Wow, 20mhz with only 6 hop channels sounds like it's spread a bit thin. Although, does anyone know if there's a definite advantage to running less hop channels?

I recently tried bumping up the hop channel count to 20 channels over 435-450MHz, and had a weird link lock issue & fly-away; my quad lost signal at close range, and the RX couldn't re-establish a link no matter what I tried, including rebooting the TX.
Looking at this thread, Dragon might use 12 channels to 22 channels. The question would be what's the width of those channels. I think Dennis Frie is running point on development for Dragon Link now. You could always ping him.

http://fpvlab.com/forums/showthread....-other-systems
typicalaimster is online now Find More Posts by typicalaimster
RCG Plus Member
Latest blog entry: I was bored
Reply With Quote
Sign up now
to remove ads between posts
Old Today, 12:34 AM
kha
openLRSng haxor
Finland, Espoo
Joined Mar 2011
2,010 Posts
Quote:
Originally Posted by changosurf View Post
which RF modules do the dragon and EZ run? how about the MCU's? are they STM's?
Ezuhf uses the same SiLabs chip that's on rfm22 and PIC MCU.
kha is offline Find More Posts by kha
RCG Plus Member
Reply With Quote
Old Today, 12:37 AM
Stuart
srnet's Avatar
UK, Cardiff
Joined Dec 2008
3,330 Posts
Quote:
Originally Posted by changosurf View Post
How much benefit does the on-board low-pass filtering *really* provide? Is it minimal or does it make a huge difference? Do on-board filters also cause some dB attenuation in the same way that the inline SMA filters do?
The low pass filter is really required to be fitted in any case, to meet the requirements for out of band transmissions. The 1W version especially puts out a lot of 3rd Harmonic, and the filter is almost cerrtainly required for both units to be legally sold in the US and Europe.

Having tried one of the Minicircuits filters, the insertion loss (at 433Mhz) was so minimal that I could not measure a differance in recieved signal.

So if the effect of the filters (or at least good ones) is minimal then the extra benefit of filtering out 1.2Ghz video has to be a good thing.
srnet is online now Find More Posts by srnet
Reply With Quote
Old Today, 03:32 AM
Stuart
srnet's Avatar
UK, Cardiff
Joined Dec 2008
3,330 Posts
Quote:
Originally Posted by typicalaimster View Post
The question would be what's the width of those channels.
The Si4432 is a simple FSK device, so the width of the channel is whatever the deviation is set to.

The smaller the deviation the better the reception (less noise) but in practice there does not appear to be a significant differance in receiver performance between 5khz deviation and 20khz.

And at the lower deviation, the reciver AFC has a harder job to do (in effect makes the RX less sensitive) , which if the RX and TX pairs are not calibrated to be close together, can be an issue especially at higher data rates (less time for preamble).
srnet is online now Find More Posts by srnet
Reply With Quote
Old Today, 05:23 AM
surf monkey
changosurf's Avatar
United States, CA, San Diego
Joined Aug 2011
1,255 Posts
so, practically speaking, what are the pros & cons of running a higher hop channel count vs just a few hop channels?

I'm guessing that there's a small time penalty/delay when running a higher hop channel count, but is it noticeable and/or can it be problematic, or should it be a non issue?
changosurf is offline Find More Posts by changosurf
Reply With Quote
Old Today, 05:39 AM
kha
openLRSng haxor
Finland, Espoo
Joined Mar 2011
2,010 Posts
Quote:
Originally Posted by changosurf View Post
so, practically speaking, what are the pros & cons of running a higher hop channel count vs just a few hop channels?

I'm guessing that there's a small time penalty/delay when running a higher hop channel count, but is it noticeable and/or can it be problematic, or should it be a non issue?
With openlrsng the only penalty from higher hop count is slightly longer initial link and relink after total cutoff.

With low rate (32packets/sec) and 16 hops this may be upto 16x16 packets i.e. Around 8 seconds but that happens only if just one of the 16 channels gets packet thru, normally it relinks within less than half sec.
kha is offline Find More Posts by kha
RCG Plus Member
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product OpenLRS - Opensource Radio Control System form Flytron MelihK FPV Talk 132 Dec 25, 2013 05:35 AM
Sold To trade or sell: my new firmware DL rx for your old firmware DL rx signflyer FPV Equipment (FS/W) 4 Apr 24, 2012 10:49 PM
Sold Flytron OpenLRS Receiver v1 x3 $125 Shipped mrfliboy FPV Equipment (FS/W) 1 Nov 05, 2011 04:20 PM
Discussion Flytron's OpenLRS available now CrashingDutchman FPV Talk 30 May 28, 2011 05:36 AM
New Product New web shop, New product *EMI P-38 Forked Tail Devil * infinityhobby Product Announcements 60 Nov 03, 2006 07:48 PM