Re: [Freetel-codec2] Codec2 repeater

Thanks Jeroen, I'll take a look as advised. I had something similar in mind. Adrian On 7 December 2017 14:51:23 EET, Jeroen Vreeken wrote: >Hi Adrian, > >On 12/07/2017 11:27 AM, Adrian Musceac wrote: >> On 12/7/17, Sebastien F4GRX wrote: >>> -replacement of

Re: [Freetel-codec2] Codec2 repeater

Hi Adrian, On 12/07/2017 11:27 AM, Adrian Musceac wrote: On 12/7/17, Sebastien F4GRX wrote: -replacement of DSTAR/DMR using codec2 and HAM CALLS as identifiers, using a decentralized user database that prevents ANY SINGLE INDIVIDUAL from controlling/restricting user access

Re: [Freetel-codec2] Codec2 repeater

On 12/7/17, Sebastien F4GRX wrote: > > -replacement of DSTAR/DMR using codec2 and HAM CALLS as identifiers, using a > decentralized user database that prevents ANY SINGLE INDIVIDUAL from > controlling/restricting user access > Hi Sebastien, I understand your concern about

Re: [Freetel-codec2] Codec2 repeater

I agree with you for the open side of things. Anything closed is useless. What makes sense to me is to develop OPEN ham radio digital networks, for multiple reasons: -control and understanding of the technology -interoperability and ability to be fixed and improved by anyone -independence

Re: [Freetel-codec2] Codec2 repeater

Well written, Gulik! Thanks. 73, DC6NY -Ursprüngliche Nachricht- Von: Gullik Webjorn [mailto:gullik.webj...@corevalue.se] Gesendet: Mittwoch, 6. Dezember 2017 23:32 An: freetel-codec2@lists.sourceforge.net Betreff: Re: [Freetel-codec2] Codec2 repeater I think it is useful to think

Re: [Freetel-codec2] Codec2 repeater

I think it is useful to think about WHY you would want to introduce "new technology". It does make sense to take advantage of current development concerning modulation and bitrate, and in this area Ham Radio is far behind. As for TDMA, why would we want that ? Well, I feel separate channels

Re: [Freetel-codec2] Codec2 repeater

Perhaps it is possible. However, we have repeaters around here with more than 200 km coverage radius, and I don't see TDMA solving both capacity and coverage. Time will tell. Glen, thanks for expanding on LTE. I am not deeply familiar with the LTE PHY and I don't intend to copy it, just

Re: [Freetel-codec2] Codec2 repeater

Hi Adrian, Consider this: with carrier per user instead of timeslot per user, you don't have the distance limitation that TDMA introduces. I think that's more a limitation of existing protocols. For example we could design a TDMA protocol to handle longer distances, or use probe packets

Re: [Freetel-codec2] Codec2 repeater

For a 16kHz wide or 10kHz wide IF filter with non linear demodulation, I consider 2FSK the mode to choice where the bitrate can be satisfied . 4FSK takes a big hit in this implementation case, for reasons outlined in many places and many times here and elsewhere. (DMR/P25 chaose 4FSK to

Re: [Freetel-codec2] Codec2 repeater

actually LTE doesnt quite work that way LTE used OFDM on uplink and downlink. The entire operator's LTE spectrum is divided up into 15kHz subchannels which are generated/decoded in the usual OFDM FFT manner. User payload is transmitted using 'resource blocks' (RB), which I think are 12

Re: [Freetel-codec2] Codec2 repeater

It is always useful I think in every conversation about 2 and 4 fsk  to qualify the implementation... IE optimal 4 receiver 4fsk versus 4fsk in a wide non liear demod passband  etc etc IMO, the implementation method it really needs to be rammed home when forming comparisons . particular the

Re: [Freetel-codec2] Codec2 repeater

OFDMA (not OFDM) is used as an access mode in LTE in combination with TDM. I'm toying with the idea for a while now, but with 5-6 hours a week available I haven't made much progress lately. Regarding 4FSK, personally I see no advantage over 2FSK. It's certainly more complicated to get working.

Re: [Freetel-codec2] Codec2 repeater

/17 12:01, freetel-codec2-requ...@lists.sourceforge.net wrote: Subject: Re: [Freetel-codec2] Codec2 repeater From: Gullik Webjorn <gullik.webj...@corevalue.se> Date: 05/12/17 12:00 To: freetel-codec2@lists.sourceforge.net Hmm, if we think of a modulation index around 1, Ca

Re: [Freetel-codec2] Codec2 repeater

Oops, I obviously meant multi-user multi-carrier, aka on demand carrier allocation. Was tired last night. Here is my motivation: in our country we have a national analog network based on svxlink, and when a user transmits he is heard across the country on a single audio channel, but this means

Re: [Freetel-codec2] Codec2 repeater

Whenmouth On 05/12/17 12:01, freetel-codec2-requ...@lists.sourceforge.net wrote: Subject: Re: [Freetel-codec2] Codec2 repeater From: Gullik Webjorn <gullik.webj...@corevalue.se> Date: 05/12/17 12:00 To: freetel-codec2@lists.sourceforge.net Hmm, if we think of a modulation index around 1,

Re: [Freetel-codec2] Codec2 repeater

indeed commercial 4FSK implementations are more about bandwidth than sensitivity. Frequency spacing between to tones is bandwidth optimizated not system sensitivity optimized. if we consider each of the 4 tones of 4FSK  being received by a separate receiver (easier to conceptualize) , each

Re: [Freetel-codec2] Codec2 repeater

Hmm, if we think of a modulation index around 1, Carsons rule says Bt = 2*(deltaF + fm ). If it is the modulation index that governs SNR in the recovered baseband, the same index will occur at 1/2 deltaF if we reduce fm by 2, i.e. symbol rate. Thus 4FSK would require half the swing ( for

Re: [Freetel-codec2] Codec2 repeater

Hi Glen, I think David might have been referring to the OFDM mode used by FreeDV, ie single user multicarrier. I was talking about multi-user single carrier. Cheers, Adrian On 12/4/17, glen english wrote: > Hi Adrian > > Please describe the differences asyou understand

Re: [Freetel-codec2] Codec2 repeater

Hi Adrian Please describe the differences asyou understand them between OFDMA and OFDM Are you sure ... ? Glen :-) On 5/12/2017 7:36 AM, Adrian Musceac wrote: OFDMA (not OFDM) -- Check out the vibrant

Re: [Freetel-codec2] Codec2 repeater

> > + OFDM isn't needed unless your bandwidth is significantly wider, as its > a flat fading channel. Single carrier PSK/QAM is fine and has a better > PAPR. M-QAM only needed if you want wideband data, not needed for voice > as we have good compression. > > + Can't seen any good reason for FDMA,

Re: [Freetel-codec2] Codec2 repeater

Hi Adrian, Fine business on your experiments. My thoughts: + I like 4FSK as it's constant amplitude, simplifying the PA and rx (limiting amps can be used at IF), and the modems are easy to get working at ideal performance. It's reasonably bandwidth and power efficient, especially as we

[Freetel-codec2] Codec2 repeater

Hello, Yesterday I commited support for same-mode Codec2 repeater (digital to digital). Apart from voice frames, now station identifiers and text messages also get digipeated. For now the Codec2 audio gets decoded if forwarded over the VoIP connection and re-encoded at the other end for RF