Yesterday Evariste, F5OEO demonstrated FreeDV 800XA and rpitx working
together:
https://twitter.com/F5OEOEvariste/status/1007192855679504384
rpitx is software for the Raspberry Pi that turns it into a transmitter,
using clever programming of the PLL and GPIO hardware:
https://github.com/F5OEO/rpitx
I'm interested in moving this work forward. A nice next step would be
building a HF or UHF FreeDV transmitter with a few watts power output
that meets ITU Amateur Radio Specs of spurious components being down by
43dB + 10log10(P).
Cheers,
David
On 15/06/18 07:20, Alan Beard wrote:
Hi David,
Anytime if you want an ARM platform to run on, ask me
for a logon (RDP) to our Men's Shed box. It's a web and file server
on our ADSL line. Has plenty of disk, 1Tb.
Linux: Fedora 25
It's a Banana Pi (original) of course, kills our power bill using
about 5W.
Electricity is expensive. a 100W PC will cost $300 per year 24x7!!
Alan VK2ZIW
On Thu, 14 Jun 2018 14:43:35 +0930, David Rowe wrote
Hi,
Just want to point out that, last time I tested them, the 4FSK
waveforms
(FreeDV 2400A, and 800XA) work just fine - unmodified and without a
scrambler.
800XA is being used by people over the air - in fact I'm working
with some UK Hams on exciting high power experiments using simple
and compact Class E amplifiers. There is a lot of link margin
possible compared to OFDM waveforms through linear PAs.
Now 800XA is a FreeDV GUI mode that anyone can run ..... pls feel
free to try it.
Two years ago Brady ran 2400A (using a 4FSK modem) on the SM2000
prototypes which use the stm32 - Glen IIRC you were in the Gipstech
audience :-)
So what we have is:
i) Code that works on the x86 platform
ii) Code that doesn't on the stm32
This suggests a porting issue to me. Steve - happy to work with you
on a series of unit tests to take us from x86 FreeDV API cmd line
test programs to working code on the stm32. It is possible there is
some corner case that we are missing, if so some careful unit tests
will show that up.
Cheers,
David
On 14/06/18 13:20, Steve wrote:
Yes. You can't see it on the FreeDV spectrum display, as that display is
filtered and averaging. But I'm sure an oscillator or two disappears.
This particular scrambler resets itself every frame. It has a starting
bit pattern. So every modem frame starts-off with the same value, and is
only 64 bits long (two codec frames). So errors may only be 80 ms in
length, before the next modem frame.
The additive scrambler for HORUS was taken out of wikipedia
1+x^{{-14}}+x^{{-15}}
On Wed, Jun 13, 2018 at 10:37 PM glen english <g...@cortexrf.com.au
<mailto:g...@cortexrf.com.au>> wrote:
The downside of most scramblers (I dont know what is used here) is
that
you can get error propagtion in a scrambler.
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Consider the Christmas child.
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70 Wedmore Rd. Sun Solaris, AIX, HP/UX, Linux, SCO, MIPS
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