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Re: SDR-1000 (was FT-847 discontinued?)



All serious contesters, including me,  using the CW keying that Frank 
(AB2KT) and I wrote for the SDR-1000, use an external keyer.   At 60 
WPM, there is a 1.5 dit delay between key closure and the dit arriving 
at the speaker using the internal, software only keyer.

On the other hand, if I allow the sidetone to mute during CW 
transmission and use my keyer sidetone,  CW works perfectly.  The 
waveforms generated are "perfect" shape.

In addition (irrelevant to most VHF+ and satellite users), the receiver 
has an IP3 of +29 dBm and a dynamic range of 99 dB.  By the way, that is 
a 2 KHz.   It will be the same at 8 KHz or 500 Hz.  The only reason 
these numbers are no officially listed is that the ARRL does not have 
adequate equipment to measure the thing at 500 Hz.

I am unhappy with transmit at the moment because we transmit the SSB (in 
I/Q form) at ) 0 Hz for the carrier.  All serious users of the SDR-1000 
use a 4 input 4 output card.  This allows monitoring on one channel and 
IF transmission on the other stereo pair.  On the other hand,  we just 
drastically improved the efficiency of the algorithms.  These 
improvements are in beta form (software) since the directX display is 
still a work in progress.   From 5 versions ago,  the software consumed 
40-50% of my laptop CPU.  This is now in the single digits.  This is a 
2.2 GHz P4 Mobile.

There is an email group that I run

http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz

The latest features of the code include interconnection with "soundcard" 
programs such as MMTTY, MMSSTV, MixW, etc. are completely NO WIRES.   
Both the soundcard interconnect and the serial port control and the cw 
keying are done with virtual soundcards and virtual serial ports.

I would say that the most serious VHF'ers using the SDR-1000 now include:

Mike King, KM0T, a super VHF plus contester.   He is just kicking behind 
using the SDR-1000. 

http://www.km0t.com/

Also,  Steve Costro, coowner and operator of Down East Microwave (he and 
his wife run/own the business) recently got on 6 meters for the first 
time because of the SDR-1000 noise blanker.

Both Frank and I have cut way back on the amount of time we can spend on 
the SDR-1000 software because of realignment of our priorities more 
towards AMSAT.  That said, the recent modifications and improvements to 
the SDR-1000 software DSP (which we are responsible for), are as good as 
anything we have done in the previous many months.

I would like the SDR-2000 (hypothetical, nonexistent radio) to have a 
much improved form factor,  separate transmit and receive IF's, etc.  
coupled with decent transverters, it will be the cat's meow in satellite 
radios.  I would also like it to have hardware generation of CW, and 
full QSK operation.  In other words,  I want my cake and to eat it too.

Bob
N4HY
Coauther SDR-1000 DSP with AB2KT
AMSAT VP Engineering



John P. Toscano wrote:

> Dave G. wrote:
>
>> The problem for high speed CW lies in the inherent delay with the DSP 
>> processing algorithms. IMHO because of that delay it's not yet a 
>> serious contest rig YMMV!!
>
>
> Dave (or anyone else on the list who knows):
>
> Is the "slow" CW speed only a function of computer-generated CW?  If 
> so, couldn't you get around that problem by using an external keyer?  
> The MFJ-495, for example, allows you to send CW via straight key, 
> paddles, a PC keyboard plugged directly into it, or via a serial data 
> stream from a computer.  It handles speeds up to 990 WPM (or so they 
> say), which oughta be fast enough for almost anyone.  :)  (Heck, if I 
> could reliably work CW at a "mere" 20 WPM I'd be ecstatic!)
>
> Or is the SDR not able to send fast CW even if it doesn't have to 
> synthesize the CW from keyboard commands on the same PC that is 
> supporting the digital encoding/decoding process?  It just seems odd 
> to me that it could encode voice into an SSB or AM or FM signal, but 
> simple "on/off" sequences of Morse code would be hard for it to do...  
> But I'm certainly very uneducated (at least so far) about the whole 
> SDR DSP process, so maybe I'm way off base...
>
> If the problem is the delay between hitting the dit or dah side of the 
> paddle and the time that you hear feedback from the monitor speaker, 
> it should be possible to listen to yourself send only from the output 
> of the keyer, and have the SDR not echo what you send back to your 
> ears. Then, it doesn't matter if it takes an extra 300ms for your CW 
> to finish transmitting before the person on the other end can respond.
>
> Or am I still missing something totally?  (These are honest questions, 
> I'm not trying to take pot shots at anyone, I really don't know the 
> answers to them.  Since I've been tempted to step into the SDR-1000 
> world "one of these days", I'd really like to know more about it.)
>
> 73 de W0JT
> ----
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-- 
Laziness is the number one inspiration for ingenuity.  Guilty as charged!
----
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