I've taken a look on it. ( ->
http://www.ti.com/lsds/ti/microcontroller/arm_stellaris/overview.page )
The hardware seems quite good, when comparing on
http://www.ti.com/lsds/ti/microcontroller/arm_stellaris/product_search.page
... They did not pointed any prices to me (propably because I looked at
the TI LM4F230 series...)
I think 256kB flash will be enough to implement Codec2 in ''full rate''
(2400bit/s) as well as ''half rate'' (1200bit/s) [implementing all other
modes with 1300; 1400; 1600 and 3200 bit/s would require too much space]
- hopefully two channels half rate simultaneously.
I would likely use two of them anyway, for independent simultaneous
encoding and decoding (I guess processing load may vary a lot in order
to keep the fixed bandwith of Codec2 depending on background noise and
the voice characteristics...)
Now it just needs an implementation for it... Regarding the development
tools from TI, this should be possible from the sourcecode.
At this point, the microcontroller would be turned into a ''DSP with
A->/D->A converter'' - propably capable to handle the entire pipeline
from voice input to digital I/O.
Like this:
--------------
Microphone (Speaker)<----> | TI LM4F230 | <----> digital [bitwise] I/(O)
--------------
Propably it needs an additional driver for A/D D/A Audio conversion. A
simple one with a sampling rate of 8kHz (or a straight multiple like
16kHz / 32kHz) would be fine...
Thanks,
Netzblockierer
Am 02.04.2013 04:52, schrieb Bruce Perens:
> TI Stellaris might be the least expensive platform that could run the
> codec. The development kit is $5. It's a Cortex M4F. It might be
> difficult to beat that on either cost or power consumption. Thanks
> Bruce On 4/1/2013 10:08 AM, Netzblockierer wrote:
>> Hi, I just want to ask if someone tried to implement the Codec2
>> Encoder/Decoder in Hardware? I would really appreciate such a
>> Hardware - Encoder, that can be easily integrated in SRD (short range
>> devices) digital radio, such as PMR/LPD/Freenet or CB. As for now, a
>> DSP or FPGA - solution (with a small piece of code to flash in, of
>> course) would be fine. Mostly, the bitrates of 2400bit/s and
>> 1200bit/s would be interesting, in order to test out simplex, duplex
>> and even quadplex configurations - making it possible to transmit 2
>> streams paralell @ 1200bit/s each while recieving the same bandwith.
>> As in http://www.rowetel.com/blog/?page_id=452 (fig. :
>> http://www.rowetel.com/images/codec2/FDMDV2_blocks_sm.png ) shown,
>> this would make Codec2 ideal for transmitting voice and data
>> simultaneously. Besides, a configuration of 2 Encoders per direction
>> (both encoding 2400 bit/s and 1200 bit/s) may offer the opportunity
>> to transfer data while continuing regular voice radio, and simply
>> switch the bandwith ''just-in-time and on-demand'': Something that
>> could really open Codec2 to new application fields (like sending GPS
>> positioning data during an emergency broadcast.) In terms of mobile
>> communicaton, this could also enable SMS-like messaging. Active
>> relays may also become able to keep the same channel for both peers
>> that are connected via a relay, without ''loobacks'' of signals when
>> using omnidirectional antennas for transmission and recieving. Also
>> signals may be relayed with lesser latency (close-to-realtime!)
>> instead of ''recieving-buffering-forwarding''. The relay could become
>> completely transparent. Normally, this problem is solved in GSM with
>> fast switching of channels and timeslots. (217 frequency hops per
>> second!) As for ham-radio, this seems to be disturbing: short bursts
>> may not be identified as such or identified as noise by other
>> stations, and thereof they may accidentally interfer the broadcast.
>> It is by concept essential to make a transmission identifyable as
>> such for other users - otherwise, there would be chaos! If such a
>> solution exists, I may try it with my CB radio, as it promises fast
>> installation even for unexperienced users (connects as microphone
>> [with PTT-trigger] and speaker) as well as the opportunity, to
>> install it on a much lower level (replacing the encoder/decoder of
>> digital SRDs) for hardware hackers... Maybe this is something that
>> may be developed. Besides, an implemetation of Codec2 without the
>> need of a floatpoint unit would decrease hardware implementation
>> complexity - as Codec2 does not necessarily requires it by concept.
>> Yours faithfully, Netzblockierer
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