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 this is just commercial hardware (e.g. APCO, etc.) driving the R&D in these radio manufactures, and their ham products just don't see the investment... if their R&D were really experimenter/hobiest focused their $2500 radios would be narrow bandwidth optimized SDRs (e.g. soundcard ADCs, e.g. 192KHz 24bit) with very linear moderately low power amps (e.g. 30-40dbm) and nice front end filters and LNAs for the ham bands, and a computer with a fpga like the novena, and a vctcxo and a $15 gps module to condition it... or, in other words, nothing like their current products. So yea, of course they're pushing codecs and modulation schemes that seem like they're just recycled from the commercial public safety radio applications: They are. Not that all of the requirements are nuts, they're trying to be very tolerant of very limited hardware in HTs... but it seems that cell phones have become ubiquitous, dirt cheap, and long talk-timed without always having (and potentially, because they don't have...) crazy compromised backwards compatibly modulation. E.g. I think LTE is OFDM with up to 64QAM running on the carriers. I dunno how many hams would actually be using this by plumbing audio I/O from existing radios into their computers. Thats actually a fair bit of work to setup and get working right, and certainly not very mobile friendly... as opposed to a DV dongle for receive only... or the analogus plug and go hardware for tx which could be created at a still-affordable price. ------------------------------------------------------------------------------ Dive into the World of Parallel Programming! The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
