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Re: Re: Proposal: SDR-DSP receiver



Hi John,
Well at least, I can comment on the MCU and RS-485 thing.. I have done 
already a DDS project with encoder, LCD display and math algorithms in a 
PIC16F877, so this was kind of a great board. If RS-485 is identical to 
LVDS, this should also be no problem.. I am working with LVDS on a daily 
basis in my lab..

Alternatively, the PIC family also has devices with USB integrated by 
now.. but this is of course my biased comment, as I do only in PICs.. 
any other MCUs to consider?

I would strongly recommend to keep such a project stand-alone. Some 
people are indeed interested in signal analysis on a PC (there the USB2 
port is superb!) but the majority just want a knob to tune..

73s Achim, DH2VA

John B. Stephensen wrote:

> I've been controlling my radios from a PC since 1991 and am getting tired of the
> restriction so I designed the DCP-1 to operate standalone. For now the DCP-1 has
> to be attached to a PC for software development, but after I'm done I want more
> mobility.  I've got 25 keyswitches, two shaft encoders and a 40x121 dot graphics
> display, but haven't decided how to use them.
> 
> A keyboard and display could attach to the DCP-1 through the SPI port, via the
> USB port or via the RS-485 port. SPI is the cheapest option if the controls and
> display are packaged with the DCP-1 board. However, for a few more dollars an
> 8-bit MCU and RS-485 transceiver would allow for a remote control head several
> hunrded feet away. The last, and most expensive, option is to make a small PCB
> with a 12MBPS USB hub, USB host controller, 32-bit RISC MCU and an SDRAM chip.
> This last option would allow the most flexibility as it would allow the
> integration of any USB device in a mobile environment.
> 
> Any suggestions?
> 
> 73,
> 
> John
> KD6ZOH
> 
> ----- Original Message -----
> From: "Achim Vollhardt" <avollhar@physik.unizh.ch>
> To: "AMSAT Bulletin Board" <amsat-bb@AMSAT.Org>
> Sent: Wednesday, 31 March, 2004 05:58 UTC
> Subject: [amsat-bb] Re: Proposal: SDR-DSP receiver
> 
> 
> 
>>Hello all,
>>nice thread started.. just to clarify: which of those projects are able
>>to run without PC support, e.g. as a portable receiver for sat operations?
>>
>>KD6OZH's project: probably yes , Audio Codc on board, needs perhaps some
>>user knobs and buttons
>>
>>USRP, DSP-10: not to my knowledge..
>>
>>Please comment and correct where necessary.. the lead batteries for
>>field ops are heavy enough, I don't want to take my laptop with me as
>>well.. :)
>>
>>73s Achim, DH2VA
>>
>>
>>John B. Stephensen wrote:
>>
>>
>>>Hello Achim and Kaj,
>>>
>>>The dynamic range is determied by the level of the signal artifacts produced
> 
> by
> 
>>>the ADC and these get worse as the RF frequency goes up. The AD9244 has a 90
> 
> dB
> 
>>>dynamic range when the input signals are limited to 45 MHz. By 240 MHz the
>>>dynamic range has dropped to 70 dB.
>>>
>>>I was planning to convert the RF to 10.7 MHz and digitize there to get the
> 
> best
> 
>>>performance out of the ADC. I've got a partially assembled receiver board
> 
> with a
> 
>>>350MHz 2MHz-wide first IF and an assembled but not yet tested 60-2150MHz LO
>>>board. Transmitting is easy. You can get quadrature modulator chips for
>>>50-3500MHz so all that is needed are baseband I and Q signals. That's why my
> 
> DSP
> 
>>>board has two DACs.
>>>
>>>73,
>>>
>>>John
>>>KD6OZH
>>>
>>>----- Original Message -----
>>>From: "Achim Vollhardt" <avollhar@physik.unizh.ch>
>>>To: <kaj.wiik@iki.fi>
>>>Cc: "AMSAT Bulletin Board" <amsat-bb@AMSAT.Org>
>>>Sent: Tuesday, 30 March, 2004 07:30 UTC
>>>Subject: Re: Proposal: SDR-DSP receiver (was: Re: [amsat-bb] Cube sat and
> 
> DSPs
> 
>>>(was Re: cube sat))
>>>
>>>
>>>
>>>
>>>>Hello Kaj,
>>>>good comments.. i'll reply below.
>>>>
>>>>
>>>>
>>>>>On 15:02 2004-03-30, Achim Vollhardt wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Proposal is to is a 65 MSPS ADC with the digital down converter and
>>>>>>DSP.. so possible reception would be somwhere between 0.1 and 30 MHz.
>>>>>>Perhaps direct reception of the aliased image of 144 MHz (at 14 MHz)
>>>>>>would be possible as well.. a common problem like bad large signal
>>>>>>performace is negligible as we deal with sat-downlinks.. we don't
>>>>>>have large signals!!
>>>>>
>>>>>Huh, at two meters, you must be kidding!
>>>>>
>>>>>What's wrong about
>>>>>http://www.proaxis.com/~boblark/dsp10.htm
>>>>>with
>>>>>http://www.fidalgo.net/~wa7gxd/dspx.html
>>>>>
>>>>
>>>>DSP10: you need again a PC to control it.. That's not the idea.
>>>>DSPX: could be a building block for my proposal, I already spoke to Lyle
>>>>Johnson..
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>The sample rate should be compatible with the signal bandwidth, not the
>>>>>signal frequency. You'll end up throwing most of the data away and will
>>>>>have to deal with nasty problems with high speed logic signals when
>>>>>using high speed converters (e.g. 65 MSPS, 10 bit only!).
>>>>>
>>>>
>>>>there is some thing called oversampling and coding gain.. I won't describe
>>>>this here, but actually you can increase system performance with a 65 MSPS
>>>>ADC.. at it is 14 bits, not 10 bits.. so dynamic range is over 80dB.. with
>>>>a variable gain amplifier(controlled by the DSP) , you end up with 125dB
>>>>range.. should be enough for Sat-operations.
>>>>
>>>>73s Achim, DH2VA
>>>>----
>>>>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
>>>>Not an AMSAT member? Join now to support the amateur satellite program!
>>>>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>>>>
>>>
>>>
>>>
>>--
>>
>>-------------------------------------
>>     Achim Vollhardt
>>     Universitaet Zuerich
>>     Physik Institut, 36H24
>>     Winterthurerstrasse 190
>>     CH-8057 Zuerich
>>
>>     tel: 0041-1-6355742
>>0041-1-6355704 (fax)
>>
>>     email: avollhar@physik.unizh.ch
>>
>>----
>>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
>>Not an AMSAT member? Join now to support the amateur satellite program!
>>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>>
> 
> 
> 

-- 

-------------------------------------
     Achim Vollhardt
     Universitaet Zuerich
     Physik Institut, 36H24
     Winterthurerstrasse 190
     CH-8057 Zuerich

     tel: 0041-1-6355742
	 0041-1-6355704 (fax)

     email: avollhar@physik.unizh.ch

----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
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