Re: [Freetel-codec2] LPCNet at 1700 bits/s

On Mon, Mar 4, 2019 at 5:53 PM Adrian Musceac wrote: > How does this scale for normal hams though? Do each of us need a huge > GPU and voice samples to even be able to use this? I am afraid that > this might have even less success with hams than current FreeDV > releases. The trained network is

Re: [Freetel-codec2] Codec2 parameter optimization

On Sun, Feb 24, 2019 at 9:24 PM Jeroen Vreeken wrote: > > Hi David, > > 52bits per 30ms might work out nicely. > > 30ms at 2400baud is 72 bits. If we use a 16 bit uw there are still 4 > bits to spare. > I don't think FEC is that important when using an existing FM system. > For more advanced work

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

On Mon, Sep 18, 2017 at 9:14 AM, glen english wrote: > The only real fix is slowing down the symbol rate. A true diversity receiver is also a real fix. -- Check out the vibrant tech community on

Re: [Freetel-codec2] 4FSK with random bits

On Wed, Mar 23, 2016 at 10:49 PM, glen english wrote: > should be able to pass continuous random sequence. that sort of testing > usually finds and breaks clock and bit recovery under pathological > conditions. testing can take 'quite a while' - days- to test almost every >

Re: [Freetel-codec2] Smoothing the digital cliff (4+4 QAM bitrate peeling idea)

On Mon, Sep 7, 2015 at 3:18 AM, David Rowe wrote: > Curiously, I haven't had a _single_ report of a high SNR path that > breaks FreeDV 700(B). For example a path that works well for SSB, but > makes the FreeDV 700 modem fall over, would indicate the modem can't > handle the

Re: [Freetel-codec2] RX chip CMX994

On Mon, Feb 16, 2015 at 10:43 PM, glen english g...@cortexrf.com.au wrote: I'm excluding space diversity RX for the mobile end (while very very effective) because it is a pain For a HT spatial diversity is obviously nuts. For a mobile-- antenna on the roof and trunk or on opposite sides is

Re: [Freetel-codec2] Orlando Hamcation: Algoram HT of the Future Demo, Overview, and Progress Report

On Sun, Feb 8, 2015 at 7:16 AM, Bruce Perens br...@perens.com wrote: Here are the target features of this version, most of which are already tested and working: Hopefully there will be room to add (or already included) a GPS receiver. Beyond the very useful direct applications for positioning

Re: [Freetel-codec2] GMSK simulations

On Mon, Dec 22, 2014 at 11:54 PM, glen english g...@cortexrf.com.au wrote: It is really a bit simpler than all that thwere is a drive in mobile comms to increase density. For an FM modulation, having four states per symbol instead of two does just this, reduces bandwidth. I think a lot of

Re: [Freetel-codec2] GMSK simulations

On Sun, Dec 21, 2014 at 12:05 AM, glen english g...@cortexrf.com.au wrote: Easy when you've got a 70K logic cell FPGA, but still possible on STM32-4, I think you need to come up with a clever way to run the demod Well keep in mind that there can be multiple target demodulators for this. If a

Re: [Freetel-codec2] FSK over FM

On Sat, Dec 13, 2014 at 10:50 PM, David Rowe da...@rowetel.com wrote: I've started taking a look at modems for VHF FreeDV, starting with 1200 bit/s FSK over FM: http://www.rowetel.com/blog/?p=3799 Take a look at GMSK. Make sure you're looking at a sufficiently complex GMSK decoder, when

Re: [Freetel-codec2] introducing SmartMic

On Wed, May 21, 2014 at 5:01 AM, David Rowe da...@rowetel.com wrote: Hello List, I just posted an introduction to SmartMic - an embedded version of FreeDV that doesn't need a PC: http://www.rowetel.com/blog/?p=3125 If would be great if some of the talented readers of this list

Re: [Freetel-codec2] Encryption and the Amateur airwaves

On Mon, Mar 11, 2013 at 3:23 PM, Bruce Perens br...@perens.com wrote: I looked briefly over the U.S. law on this issue since 1927. I think I could make a pretty good case that the justifications in 47 CFR 97.1 and the right to listen implicit in the 1st amendment to the U.S. constitution imply

Re: [Freetel-codec2] FreeDV Robustness

On Wed, Mar 6, 2013 at 2:48 PM, David Rowe da...@rowetel.com wrote: I've been talking to some Turbo Coding and LPDC guys and I now think they would be worth testing, for example with block sizes of 256 bits. While these codes are optimal at blocks with several thousand bits (a few seconds

Re: [Freetel-codec2] OFDM for FreeDV?

On Wed, Dec 5, 2012 at 6:39 PM, Bruce Perens br...@perens.com wrote: I did a talk at Lawrence Berkeley Lab today. Because the group I am working with does a lot of things that look very close to radio, I showed Mel's recent video as an example of an Open Source project where we are doing real

Re: [Freetel-codec2] PAPR and handheld operation

On Tue, Jun 12, 2012 at 1:33 PM, Patrick Strasser OE6PSE oe6...@wirklich.priv.at wrote: Am 11.05.2012 03:44, schrieb Gregory Maxwell: It should be noted that the OFDM modem with N-PSK carriers modulated with a golay complementary sequence (a rate 1/2 FEC) provides a PAPR of 3dB, which I think

Re: [Freetel-codec2] VHF codec2 modem: bit syncronisation

On Wed, May 23, 2012 at 11:19 PM, Gullik Webjörn gullik.webj...@corevalue.se wrote: Since this is a spec, why not? I think the basic idea of a sampling rate of 48000 is good, but why not allow 96000 and 192000  as well, allowing extension of the spec? After al, hw is available. 48000 should of

Re: [Freetel-codec2] PAPR and handheld operation

On Fri, May 11, 2012 at 2:14 PM, Bruce Perens br...@perens.com wrote: The reason that SSB transmission is in general not offered on HTs is that much of the power of a linear PA ends up being turned into heat. Hm. I thought it was also because they don't have stable and accurate oscillators

Re: [Freetel-codec2] PAPR and handheld operation

On Thu, May 10, 2012 at 9:15 PM, Bruce Perens br...@perens.com wrote: David, Mel, and I have been having a discussion of PAPR: peak vs. average power ratio, off of the list.  This is also called crest factor. [snip] Should we compress in software before feeding the amplifier, so that clipping

Re: [Freetel-codec2] US export controls exemption

On Sun, Nov 27, 2011 at 2:41 PM, acutler22 acutle...@yahoo.com wrote: After looking at the LVS exemption though, it points out that *everything* packaged with Codec2 must be less than $5000: http://goo.gl/VZPTc This could pose an issue of Codec2 were packaged in a large commercial telecom