I think Kenwood's calling you they are looking for someone to put the STUFF
inside their mock up radio they had at Dayton
Dave / WB0PKK
At 10:30 PM 9/13/00, you wrote:
>Here is my entry into the interesting project category -- A Kilowatt
>transistor SSB/FM/AM/CW/etc. transmitter for 160 through 6 meters.
>
> The transmit chain consists of:
>
> 1. A Mike preamp connected to a 16 Bit Analog to Digital converter
>running at a 24 KHz sample rate -- one of the tiny ones with serial data
>output.
>
> 2. A 16 Bit Digital Signal Processor chip good for about 40 mips. This
>chip can perform an intelligent VOX function (no missed syllables) by
>delaying the input signal 10 mS. The same buffer can be used to
>implement a Hilbert transform compressor (similar in function to RF
>clipping). Transmit bandwidth will be set by mode... or whim.
>
> SSB will be generated by the Weaver (third) method & the resulting I&Q
>signals will be up sampled by a factor of 32. These signals will be
>delayed to compensate for the output filter delay in the envelope
>re-modulator filter (part 5 below). A digital representation of the SSB
>envelope will be loaded directly into the modulator at a 96 KHz rate.
>
> For CW, this critter will also be able to create a variety of envelope
>shapes... from textbook perfect to simulated chirps & clicks. :-)
>
> FM is created directly by adding the digitized value of the mike
>audio, 16 bits - up sampled to 192 KHz, scaled for the desired deviation,
>to the nominal carrier setting (32 bits) and updating the DDS registers
>with those results (also at a 192 KHz rate). This method gives perfect
>FM with ridiculous control over the deviation: 1 LSB = .075 Hz @ 5 KHz
>total deviation.
>
> AM is made in the old way, by directly modulating the final amp.
>
> And of course PSK, FSK, etc will be doable.
>
> 3. A combination up-sampler, Direct Digital Synthesizer & I&Q modulator
>(a single IC) that can directly output on frequency up through 6
>meters.
> SSB is created by completing the Weaver modulation with the second mix
>directly at the output frequency.
>
> 4. A limiting amp (to make Class D) followed by a two watt stage which
>may operate either Class A for test or Class D for real.
>
> 5. A legal limit Class D amp modulated by a switching amplifier powered
>by a power factor corrected (PFC) input circuit. Output filtering &
>tuning will be by means a whole bunch of coils & capacitors switched
>by... about 32 relays. An independent SWR protection circuit will
>directly reduce the voltage to the finals, to prevent awful things from
>happening should something screw up in the software.
>
> The modulator, sampled at 96KHz, will be driven by a digital pulse
>width generator with 11 bit resolution (ECL parts -- clocked at 200
>MHz). It will implement the envelope restoration for SSB, envelope
>shaping for CW, direct modulation for AM and power control for FM, CW,
>AM, & SSB.
>
> The RF amplifier and modulator stages can be line isolated by means of
>RF transformers, plus optoisolators for the control signals, so no big AC
>power transformer will be required.
>
> 6. and almost forgot -- An 8 bit microprocessor to handle the mode
>selection, tuning, etc.driving a Vacuum Fluorescent readout for all the
>words & numbers.
>
> Finally, a 24.576 MHz master clock multiplied (by 8) to 196,608 MHz to
>clock the DDS & ECL stuff; and divided as necessary to run everything
>else.
>
> ******************************************
>
> While this sounds like a lot of stuff, it will be rather compact in the
>real world -- except for part 5. :-)
>
>
>Comments, suggestions... anybody want to help?
>
>
>73,
> Marv WC6W
>
>
>
>
>
>
>
>
>
>*
>
>
>
>
>
>
>
>
>
>
>________________________________________________________________
>YOU'RE PAYING TOO MUCH FOR THE INTERNET!
>Juno now offers FREE Internet Access!
>Try it today - there's no risk! For your FREE software, visit:
>http://dl.www.juno.com/get/tagj.
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|