[hpsdr] An idea for a project

[Steven B. Dick]

Hi Paul and group. I am completely in agreement with you that there is
opportunity in the market for a self-contained all band SDR transceiver with
knobs.  This is evidenced by many people interested in connecting an SDR
cube to a Mobo to give self-contained all-band capability.  The SDR cube was
indeed a breakthrough in that it can do all of its DSP processing in a very
low cost microcoltroller chip, the DsPIC33FJ128GP802 which costs $6.52 and
has 128 KB Flash EPROM and 16KB SRAM with DSP capabilities.  This is also
used by the AQRP Yahoo group in their SDR2GO SDR transceiver.
 
I got into software defined radio fairly recently, on a low budget. My son,
KB1RSA  had bought a softrock receiver, which worked amazingly well
unmodified, using some of the available software out there like Power SDR,
using a Windows 7 PC.  I then bought him a Softrock Ensemble transceiver,
which he just got working this week.  It is an amazing design for its very
low cost of  $74.00 but these kits are rarely  in stock  at
<http://kb9yig.com/> http://kb9yig.com/  .  Here's where my desire to have a
self-contained, hardware based rig came from.  Oh, so you need two
soundcards not one sound card which all software based solutions require.
Oh,  Rocky only runs under windows XP, not Windows 7.  By the time you equip
your PC with two good sound cards for a transceiver, the cost is rapidly
rising.  Software setup for newbies can have a large learning curve,
depending on technical level. Not for the faint hearted!
 
I believe, with the right FPGA firmware, the upcoming Hermes and Apollo
could be made into a standalone transceiver.  The knobs and display could be
done through the I2C interface and/or any spare available bits.
 
Then I started thinking why not put the entire transceiver in an FPGA using
a quadrature sampling decoder for receive and a quadrature sampling encoder
for transmit?  (but no 6 meter operation)  The FPGA could generate the QSD
and QSE signals, by pulling the two most significant bits off a digital
accumulator.  You could use a TI codec for the audio A/D and D/A functions,
and do ALL the high speed digital filtering and DSP processing in the FPGA,
and also use the FPGA to control a display and other functions  (optical
decoder, keyer, etc). The DSPIC33 could do display GUI, transmit audio
processing. The FPGA would allow a fairly wideband spectrum display, unlike
using the DSPIC as in the SDR cube. The core components would consist of the
following:
 
"Small" FPGA such as the Xilinx XC3S200A-4VQG100C 200K gates in a 100 pin
TQFP package for $11.16 Note: This is a lot easier to assemble than a large
Altera FPGA as well as lower cost.
DsPIC33FJ128GP802 microcontroller for $6.52
Microchip 24AA256 I2C EEPROM for non-volatile storage for $1.14 (The
DSPIC33F doesn't have EEPROM non-volatile storage)
T.I audio codec TLV320AIC3204 for $6.75
TDA2003H car 10W audio amp for $2.35 
 
You could still pull off audio to drive a PC and have all the bells and
whistles,  but you could still operate standalone if you want.  Having
capability to still drive a PC with software is very important for a lot of
people and you still want to be able to do this. The transmit functions
should DEFINITELY be self-contained though as this is easily implemented
self-contained and would eliminate the need for a second sound card.
 
Certainly the display device would be a large cost driver as well as the
cost of a good reference crystal oscillator.  But having a real productized
transceiver on one or at most two PC boards (separate one for the amplifier)
would go a long way which could be built as a kit would be a great product.
 
Regards,
Steve ("Digital Steve"), K1RF
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