[aprssig] Kenwood's new APRS and D-STAR HT

Stephen H. Smith wa8lmf2 at aol.com
Sun May 29 09:16:06 CDT 2016


On 5/29/2016 9:00 AM, N2MHO via aprssig wrote:
> http://www.universal-radio.com/catalog/ht/0048.html
>
> Mike, n2mho
>

Looking at the pics and brief description, I am guessing that this is basically 
a next-gen TH-D72 with

-   Color display
-   Third band (220)
-   Gen coverage HF

and a ton more firmware added.    I seriously doubt the SSB function extends to 
VHF/UHF transmit as this would require linear amplifiers in the transmit power 
amp chain.

The DSTAR feature comes from leveraging the 9600 baud packet function already 
in the D7/D72 with a bunch more tricky firmware.   D-STAR uses GMSK, a form of 
two-frequency FSK not far removed from the 9600-baud direct FSK modulation used 
for packet.

If one postulates a DSP chip of some sort (rather than the classic dedicated 
AOR TNC chip of the D7 and D72) already direct-coupled to the radio's FM 
discriminator and FM TX modulator, it would be a relatively small jump, 
entirely in firmware, to do D-STAR. Since the amount of embedded firmware in 
devices seems to follow Moore's law and double every 18 months, it would 
probably be fairly easy to make the DSP "TNC"/modem do both 9600 baud packet 
and D-STAR, by just throwing more code at it.....

_______________________________________________________

Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

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