Hi Al - nice to hear from you.
I'm trying to learn ARM cross compiling, but it would be nice to also have
some folks to check on live hardware. The only SDR I have is receive-only
(NooElec NESDR Nano2+, and your web link is NEAT!).
In the script snippet that I attached, there was a bit at the end that I
thought might have been the "figure of merit" ... if so ... I can try and
tune the knot placement based on these numbers.
Uncoded PSK Eb/No simulation:
No = 1.00 dB (1.26 linear)
Eb = 0.00 dB (1.00 linear)
Eb/No = -1.00 dB (0.79 linear)
Using: HRA_112_112
Using: HRA_112_112
Nframes: 100
CodeLength: 224 offset: 0
written: 22400
.....xxx.x.x.x...xmeasured double sided (real) noise power: 0.629226
xx.x............................................x....x....x....x..x.........x....xtotal
iters 5469
Raw Tbits: 22400 Terr: 2268 BER: 0.101
Coded Tbits: 11200 Terr: 68 *BER: 0.006*
Tpkts: 100 Tper: 17 *PER: 0.170*
I gather that having both of these numbers small is good? Minimizing on two
numbers is a bit challenging, I might just try to minimize based on
sqrt(BER^2 + PER^2) ... any thoughts would be appreciated.
On Wed, Aug 4, 2021 at 3:32 AM Al Beard <bear...@unixservice.com.au> wrote:
> *Hello Tim,*
>
> *It's great to have you onboard. I'm more of an "implimenter", by no means
> good at C or C++.*
> *So I can't help to that depth.*
>
> *I can compile code on ARM and Intel Linux platforms here and with
> transceivers, give it a go.*
>
> *So, if I can be useful.*
>
> *My SDR here in western Sydney, Australia can do Codec2 decode though
> currently in one mode.*
> *(easily changeable in a script file) Web browse 110.143.195.8:8073
> <http://110.143.195.8:8073>*
>
> *You may notice the M17 project has chosen the Codec2 modes 1600 and 3200
> to "replace" AMBE*
> *in an open source transceiver project. *
>
> *Welcome*
>
>
> *Alan VK2ZIW *
>
> *On Tue, 3 Aug 2021 17:14:15 -0500, Tim Meehan wrote*
> > Hi - I'm not extremely versed in digital modes, but I am well versed in
> optimization. I think that HAM radio should be something open source, which
> is why Codec2 appeals to me.
> >
> > Before I post a large blob of C code, I wanted to mention that I have a
> program that I have written a genetic optimizer to move spline knots around
> - and I'd be happy to run the optimizer based on BER/PER ... however ... I
> need someone to explain to me how I might generate quantities to optimize
> on. I don't need bunches of help, just enough so that I can write it
> myself.
> >
> > I found that the 16-sample clamped endpoint spline with log-spaced
> samples worked the best, so I'll chop out the higher sample density parts
> of the code. My hope was faster AND more accurate, but I think all I got
> was faster and LESS accurate. Perhaps wiser eyes than mine can help me out.
> >
> > The test script that I was using was:
> > #!/bin/sh
> > ./ldpc_enc /dev/zero - --sd --code HRA_112_112 --testframes 100 \ |
> ./ldpc_noise - - 1 \
> > | ./ldpc_dec - /dev/null --code HRA_112_112 --sd --testframes
> >
> > The code is (simply replace phi0.c with this):// phi0.c
> > #include <stdint.h>
> > #include <stddef.h>
> >
> > float coeffs_clamped_16[16] = {
> > 7.93223341e+07, 1.55433768e+07, 3.60871810e+06, 7.33752374e+05,
> > 1.65434845e+05, 3.44055511e+04, 7.62050634e+03, 1.60695364e+03,
> > 3.52218272e+02, 7.50245180e+01, 1.64584579e+01, 3.63755151e+00,
> > 8.75888035e-01, 1.72673513e-01, 6.76273536e-03, -7.75296180e-03};
> >
> > float x_16[16] = {
> > 1.00000000e-04, 2.15443469e-04, 4.64158883e-04, 1.00000000e-03,
> > 2.15443469e-03, 4.64158883e-03, 1.00000000e-02, 2.15443469e-02,
> > 4.64158883e-02, 1.00000000e-01, 2.15443469e-01, 4.64158883e-01,
> > 1.00000000e+00, 2.15443469e+00, 4.64158883e+00, 1.00000000e+01};
> >
> > float y_16[16] = {
> > 9.90348755e+00, 9.13595919e+00, 8.36843084e+00, 7.60090254e+00,
> > 6.83337448e+00, 6.06584753e+00, 5.29832570e+00, 4.53082768e+00,
> > 3.76344015e+00, 2.99656512e+00, 2.23206146e+00, 1.47840690e+00,
> > 7.71936833e-01, 2.32985688e-01, 1.92853284e-02, 9.07998596e-05};
> >
> > static size_t
> > bisect(float x, float *restrict x_data, size_t size)
> > {
> > size_t left = 0;
> > size_t right = size - 1;
> > int max_iterations = 32; /* waay higher than we need */
> >
> > while (right - left > 1 && max_iterations--) {
> > size_t middle = left + (right - left)/2;
> > float xm = x_data[middle];
> > if (x < xm)
> > right = middle;
> > else if (xm < x)
> > left = middle;
> > }
> >
> > return left;
> > }
> >
> > static float
> > spline_interpolate(float x,
> > float *restrict x_data,
> > float *restrict y_data,
> > float *restrict M,
> > size_t size) {
> > size_t i = bisect(x, x_data, size);
> > float h = x_data[i + 1] - x_data[i];
> > float z = (x - x_data[i])/h;
> > float h2 = h * h;
> >
> > float c1 = (M[i + 1] - M[i]) * h2 / 6.0;
> > float c2 = M[i] * h2 / 2.0;
> > float c3 = y_data[i + 1] - y_data[i] - (M[i + 1] + 2.0 * M[i]) * h2
> / 6.0;
> >
> > return ((c1 * z + c2) * z + c3) * z + y_data[i];
> > }
> >
> > extern float
> > phi0(float x) {
> > if (x <= x_16[0])
> > return 10.0f;
> > if (x >= x_16[15])
> > return 0.0f;
> >
> > return spline_interpolate(x, x_16, y_16, coeffs_clamped_16, 16);
> > }
>
>
> ---------------------------------------------------
> Alan VK2ZIW
> Before the Big Bang, God, Sela.
> OpenWebMail 2.53, nothing in the cloud.
>
> _______________________________________________
> Freetel-codec2 mailing list
> Freetel-codec2@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
>
_______________________________________________
Freetel-codec2 mailing list
Freetel-codec2@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/freetel-codec2
