David, Thanks for that. I knew they could be had cheaper elsewhere, but didn't know where. One problem with UK imports is that you can get stung for import duty, even on small items, which winds the cost up by a considerable percentage. If you don't pay you don't get and you then have to appeal. YUK.
On the other hand I have had lots of stuff delivered from the US and Canada without issue including the US QRP club DDR board, and the SoftRock are probably still cheaper than W&S with the duty. (Mind you they will have to pay it..) Dave G4UGM Illegitimi Non Carborundum (p.s. I know the prices sound "rip off" but they are a commercial organization with salaries to pay and a shop in the UK to heat light, insure and pay property taxes on, and lots of labour laws to conform to. I think what you see is the cost of doing commercial business, and you might reflect that we are seeing fewer radio dealers in the UK these days not more. To me that means they are making a loss and going bump) ----- Original Message ----- From: drmail377 To: [email protected] Sent: Thursday, May 15, 2008 9:00 AM Subject: [soft_radio] Re: [soft_rad] DSP -> SDR now sample point Whoa - those softrock prices from Waters & Stanton are outrageously high. Instead go to http://groups.yahoo.com/group/softrock40/ and order from the source, Tony Parks KB9YIG. Also, there's a new all ham-band RXTX kit coming out that has an Si570 synthesized clock generator on board. The Si570 equipped Softrock Lite V8.3 receiver is now shipping and Tony can now also supply the Si570 generators as well. V8.3 coverall all ham bands with four plug in filters, you change bands/frequencies via a DIP switch. The V8.3 receiver kit with four filters and an Si570 generator is $43 USD including international shipping, payment via PayPal. Some of us are looking at switching the BPF's and changing frequency with hex encoded rotary switches - just one example of how you can enhance these tiny kits. 73's David --- In [email protected], "Patricia Wilson" <[EMAIL PROTECTED]> wrote: > > I had no idea single-band boards were so inexpensive. There is a Japanese > supplier who will sell a board delivered to the US for $21. The softrock > boards though, sound like they are better documented. I just wish that > either supplier had down-loadable manuals so I could get a better idea what > the off-board needs are and what software is available/required. > BTW my PC is running Linux. Is that a bad thing? > > On Wed, May 14, 2008 at 3:47 PM, Dave Wade <[EMAIL PROTECTED]> > wrote: > > > > > --- In [email protected] <soft_radio%40yahoogroups.com>, > > "Patricia Wilson" > > <wilson.pr.gm@> wrote: > > > > > > Thank you Carlos, a useful answer. > > > > > > I am rather new to this SDR thing and have a really newby question. > > > Where in the chain between antenna and speaker should the signal be > > > sampled by an SDR? The Nyquist limit imposes a sample rate of at > > > least twice the highest frequency component so if you want to sample > > > at the input RF and that RF is 29 MHz then you need a sample rate of > > > 58 MHz which is not only pretty fast but will also produce a LOT of > > > data very quickly. On the other hand if you mix it down to a first > > > IF you lose the possibility of digitally filtering out unwanted > > > signals earlier in the signal path before they have a chance to > > > overload something. > > > > > > As with nearly everything in engineering it is a trade-off. But > > > where do most SDR's do the sampling? > > > > It depends on what you mean by "most". There are probably more "baseband" > > SDRs (in effect direct conversion) "in the field" as they are reasonably > > cheap to make and can be very versatile. The Softrock series of boards > > > > http://www.wsplc.com/acatalog/SOFTROCK-RXTX.html > > > > each of which can be squeezed to cover most of an amateur band using a > > single crystal, are probably the most populous. There are also a number of > > home brew designs. I myself have the Elektor (Dutch Magazine) design which > > is general coverage. Providing you use a pair of mixers with 90 degree out > > of phase carriers you can easily eliminate unwanted side bands and even > > demodulate FM digitally. By putting the mixer close to the antenna you > > don't > > get the same blocking issues you get with traditional multiple conversion > > Receivers, and the image problems are much reduced. > > > > These are also useful as add-ons to traditional receivers when tuned to the > > IF frequency and used to replace the filtering function. In this case you > > may still get issues from the higher level mixer, but you do get a very > > versatile set of filters. In addition you can use software (I forget its > > name and google is no help) that will simultaneously decode and display > > multiple CW signals at once... > > > > On the other hand I feel that direct sampling receivers must offer the way > > forward. Sampling directly at RF will give the best fidelity of signal. > > Trouble is at present its more expensive :-( > > > > Dave > > G4UGM > > > > > > > > -- > Patricia Wilson > Apache Junction, AZ > Member NRA, BMWMOA, AMA, ARRL > WB8DXX > BMW '06 R1200RT "Graues Gespenst" >
