(cc-ed to list)
Sure, SM1000 purchase details here:
http://www.rowetel.com/?page_id=3902
The LDPC codes have much better performance (coding gain) than Hamming
codes. I've found Codec 2 (especially the lower rates like 700) fall
over at a few % BER.
Cheers,
David
On 08/10/17 23:58,
Hi David,
Thanks for pointing me at the Octave code. I'll have to do some
reading as I'm pretty sure my implementation is buggy.
Regarding, the 700 bit/s mode, I do hope there will be no major change
in the library version, as we have to use the distribution packaging,
on stable.
Thanks,
Adrian
Hi Adrian,
There is Octave and C code for the mFSK modem we have developed in
codec2-dev, that we have tested against the ideal FSK performance
curves. Not sure I'd call it matched filter, but take a look at the code.
It's important to check your modem implementation against theory at a
Hi David,
Thanks very much for the tips! Would you suggest that the matched
filter approach is better for 4FSK as well? I am using it for 2FSK and
it works well, it's just that being lazy I wanted to avoid too much
complexity in the code for the 4FSK variant.
Regarding PSK: I have several things
On 10/5/17, Steve wrote:
> You might also do your testing in a more remote spot. The use of ISM
> in the city is probably pretty high, and interference would be an
> issue. It might not break the squelch (spread spectrum, etc), but the
> bits would be corrupted.
>
> I see
Hi David,
Thanks for the answer! I have just simulated a 2FSK modem on AWGN
channel, but this time without using FM demodulation. It performs just
like you said, ~2 dB worse than QPSK (at 5% frames dropped). This
means that the FM demodulator I used for 2400A must be introducing
some symbol
You might also do your testing in a more remote spot. The use of ISM
in the city is probably pretty high, and interference would be an
issue. It might not break the squelch (spread spectrum, etc), but the
bits would be corrupted.
I see a lot of users on that band, with just a junkbox antenna and
Hi Adrian,
This blog post compares a bunch of different modems at the 2% BER
operating point:
http://www.rowetel.com/?p=4663
Given all things being equal (e.g. sync overheads, bit rate etc) PSK is
about 3dB better than 4FSK at the 2% BER point. In practice real world
PSK modems tend to
Hi,
I was able to perform some field measurements on Sunday to compare the
performance of the 4FSK modem and the QPSK modem in the 433 MHz ISM
band.
My transmitter was set to 1 mW output power into a 2 dBi gain antenna
located at approx. 21 meters above ground on one of the buildings in
my city.